All Posts by Jennifer Faul

Summer road trips: How to breathe easy wherever you go!

The great American tradition of taking a road trip during the summer is still popular after the COVID-19 pandemic, although fuel and lodging prices may cause some to shorten their range or length of stay (skift.com).  Of those staying at home instead of traveling, 33% were concerned about their own safety and the safety of others.  At HypoAir, we want everyone to enjoy their summer, and with some precautions, a road trip can be part of it!

Make sure to pack the devices that keep you safe at home:

• TotalClean is an odorless cleaner made with iodine that is safe to clean any surface, as well as deodorize the air around it!  Use it on door handles and hotel room sinks and fixtures, 
• Germ Defender and Air Angel will clean the air and surfaces in your hotel room quickly and quietly.  Simply plug them in when you arrive (Germ Defender works great in small spaces like the bathroom, and Air Angel in larger spaces like the bedroom), and return after dinner to a cleaner room.  If you don’t have a car adapter for your Air Angel, make sure to order one so you can sanitize your car everyday while you drive!
• Disposable gloves are great to have “on hand” for high-touch areas like gas pumps.  Although they are designed to be disposed of after use, if you are running low on them, a study has shown that applying hand sanitizer to the gloves does not reduce their effectiveness or increase puncturability. 
• Hand sanitizer, of course!  It’s helpful to have a pump bottle in the car so that you don’t have to fumble with a cap or handle the bottle with hands that may be contaminated.  Hand-sanitizing wipes are great for your purse, baby bag or luggage.  You can check out our post on hand sanitizers to find some that are non-toxic.
• Masks:  Bring a good supply so that you won’t be stressed about losing or re-using a masks.  See our post about face masks here.
• Snacks and drinks: you can minimize time spent to find the right snacks, eat healthier, and spend less in general by buying snacks in grocery stores before you go on your trip instead of in convenience stores along the way. (aarp.com)
• When checking your car’s fluids and systems, consider replacing the cabin air filter and vacuuming out the car so that you’ll have fresh air to breathe for all those hours on the road. 

Stopping to eat at local restaurants is part of the fun of visiting a new area.  You may opt to choose outdoor dining, which is generally safer than indoor because of the fresh air ventilation all around you, but if the restaurant doesn’t have an outdoor option, you can try a couple different strategies to avoid viruses and germs in the air:

• Request to be seated close to the door, which naturally provides ventilation as customers go in and out. 
• Use a different kind of “mask”.  Normally when masked customers are seated at a table, they unmask to eat and have conversation, which somewhat defeats the purpose of wearing a mask into the restaurant!  Instead, you can try “nasal filters”.  There are many types and most are very comfortable and undetectable, meaning you can easily wear them, be protected, wear lipstick, and let your smile say it all!  It’s best to get a few pairs and practice wearing them at home and in public before you go on your trip, to be mindful of nose breathing over mouth breathing.  The first nasal filters were invented in Thomas Carence from Kansas City, Missouri in 1901 as a solution to hay fever (news.crunchbase.com), and then, but since the pandemic the styles and sources have multiplied. The upside of wearing these filters is that they are generally more comfortable than masks, so you’re apt to wear them all day and protect yourself from other contaminants like pollen, dust and air pollution.  Here are some styles you can try:
  • O2 Nose Filters come in 4 different sizes and the webpage has helpful videos on why and how to wear them. 10 filter sets are $14.99.
  • First Defense Nasal Screens use a safe adhesive to apply the screens, for those who are wary of sticking an object into their nostrils.  A one-week supply (7 sets) is $9.98.
  • Rhinix.com is mainly marketed towards seasonal allergy sufferers but can capture any allergen the size of pollen grains (about 15 microns).  These filters were developed in 2011 by a Danish medical student and ship from Denmark.  While driving through different sections of the country, you may encounter allergens your body does not like, therefore, these are great protection that are easy to wear all day long!

Even if it’s humid outside, indoor air conditioned environments can be very drying to your nose and lungs.  This can cause you to be susceptible to allergens, viruses and bacteria.   FEND Nasal Spray works in a different way than masks.  It hydrates your nasal passages with a blend of water, calcium and sodium to enable your own respiratory system to keep producing the mucus that protects you.  The makers of FEND recommend use at least every 6 hours by spraying it into the air and breathing the mist deeply through your nostrils. 

Hotel rooms, as we mentioned, can be of particular concern during peak travel season and when you’re not sure how the hotel sanitizes.  We gave a lot of advice in our post “Hypoallergenic Hotel Suites”; here are the highlights:

• You can find a Pure Room (that has been cleaned to specific requirements) here, or search for “allergy-free hotel (destination city)” for a variety of listings.
• If you want to find out how these rooms are cleaned, instead of calling a nationwide 1-800 booking line, try to call the local hotel directly and speak to someone who is head over housekeeping or knowledgable in their practices.
• Think about bringing your own towels, sheets or sleep sack, and staying in a hotel with laundry facilities.
• Don’t be afraid to ask for a different room if you sense that yours was not cleaned well or has a musty odor (quite common in more humid areas). 

Big cities and highways can be some of the worst areas for air pollution, and sometimes it’s necessary to drive through them.  In our post about air quality inside your car, we’ve described the technique for allowing the least amount of that pollution into the cabin where you’re breathing.

• Consider signing up for a free trial or subscription at Breezometer.com in order to plan driving routes with better air quality.
• When encountering heavy pollution, it is best to close the windows, set the ventilation to “recirc” and set the fan on low.  Also, using the air conditioning will lower indoor contaminants.
• The recirc setting should only be used for a short time, because the concentration of carbon dioxide from passengers’ breathing starts to become high.

If you’re “roughing it”--whether that means using an RV or tent– campfires are fun to make for cooking food or just marshmallows and s’mores.   Building a fire outdoors will create fine and ultra-fine particulates, however, that you should avoid breathing in by staying upwind of the smoke.  Here are some other tips from clevelandclinic.org for making a safer campfire time:

• Use only untreated wood, because burning treated wood can release toxic vapors.
• If possible, avoid using manufactured logs to start the fire; here are some tips to starting a campfire (#3 on list)
• Don’t use gasoline or lighter fluid to start or maintain a campfire; not only are they dangerous to those around the fire, they can release toxins into the air. 
• Only burn on calm days (winds less than 20 miles per hour) and where there are not burn bans in effect because of forest fire danger.

Our country and roads offer some great getaways and we hope you will take advantage of them safely!

Our New Healthy Home WishList

Sometimes, after hearing about many customers’ problems with their existing homes (problems with attics, basements, crawlspaces, inadequate ventilation, too much humidity, poor location, etc.), we just want to do a positive post on what our dream house would look like!  What if you could build a new home in any location to make it as healthy as possible?  Where would it be and how would it be constructed?  There are lots of methods and designs to choose from, so don’t get overwhelmed, just relish the possibilities! 

1. Size.  Homes have always been a showcase of the owner’s tastes, abilities, and wealth.  Most homes are built today with the current owner’s needs and plans in mind: if a couple plans to expand their family, they will try to incorporate extra rooms for more children, for example.  Size is therefore a function of meeting current and future needs, budget, and space to build on.  There is no “best size” for a healthy home, as long as all spaces are ventilated and properly maintained.  

• Don’t over-size it!  The problem with “oversizing” a home is that unused rooms still need to be conditioned and maintained, using energy.  Closing off ventilation registers in unused rooms is not good for the HVAC system or the air quality in the room.  Unused rooms should have circulating fans left on and some sort of ventilation connection with the rest of the house (door vent grilles or transom windows are great for this purpose if you want to close the door).   This article looks at the ideal house size in which to raise a family.
• Once you build a home and love where you live, it’s hard to conceive of moving in the future just because you grow out of  space.  Look at incorporating expansion into the plans at the beginning.  Here are 4 plans that make expansion easier by incorporating it into the plan.  This allows you to build “just right” and expand when needed.
• Try to find an architect who is known for indoor air quality.  It is better to use their skills in design to build a home of the right size, small or large, than to work with an architect who designs beautiful homes but does not design for air quality.

2. Foundation: We have to protect our homes from moisture coming up from the ground, and without encapsulation, crawlspaces just do not offer the best protection.  A properly waterproofed slab or basement affords better protection than a crawlspace.  Although it may not look like it, concrete is porous.  You’ll need a water barrier below it (slab) and around it (basement).  If you build in an area with very moist soil or active springs, it is important to have the proper drainage around  and under your basement.  Having a finished basement requires no water coming in, so that the air is not becoming humidified.  The temperature of basements, because they are in contact with the cool earth, is cooler, and cooler air can hold less moisture (its relative humidity will get higher).  Higher relative humidity causes everything in the basement to become more moist, risking mold growth.  So, even if you have a properly waterproofed basement, you may need to use a dehumidifier or small heater to keep the relative humidity at the proper level.  Remember that a finished basement will need to be included in the ventilation system!  
3. Attic:  Unconditioned attics can serve as a thermal “buffer” between your home and the outdoors, but they require proper ventilation, which can be difficult to get right even with the proper products (soffit vents, baffles and ridge vents).  For this reason, we recommend no attics (with the rooms’ ceilings extending to the rooflines) or conditioned attics (the thermal envelope still resides at the roofline and the attic space may be finished or unfinished).  Conditioned attics are an extension of the home below, and if HVAC equipment or any storage is located there, it is not subjected to extreme heat, cold or moisture as in unconditioned attics.  Remember, when planning for a conditioned attic space, ventilation is just as necessary as the rest of the home!  
4. Heating/cooling: In the US, the bulk of heating and cooling new construction is done by forced air systems.  That does not mean it is the best system, however.  Forced air creates pockets of warmth and cool.  Moving forced air through unconditioned spaces like attics and voids also allows for leakages.  In contrast, radiant heating creates an even, comfortable environment.   Here is a diagram that shows the difference:

According to BobVila.com, the benefits of radiant heating over forced air heating are several:

• Radiant heating consists of 50% infrared light, which is an invisible natural light that warms by proximity (ie, in the floors you walk on). 
• Air is not stratified like in forced heat systems.
• Radiant heating eliminates allergy symptoms that are generated when blowing air through the home.
• Distribution losses are nearly eliminated. 
• New products like WarmBoard heat and cool quickly and transfer heat better than traditional techniques of installing radiant heating. 
• Radiant systems can also be used to cool your home.
• Some studies show that radiant heating is up to 30% more efficient than forced air.
• Radiant heating will still need a fresh air system to exchange stale air with fresh, conditioned air.

Now, of course you can heat or cool water for radiant heating using any type of heater/cooler.  Geothermal energy uses the coolness of the earth about 18-30 feet below the surface, and only requires an electrical pump to circulate the liquid.  However, the installation costs for such a system makes payoff distant for most homes. Geothermal and radiant heating and cooling for large buildings such at the University of Southern California has been a cost-saving, long-term investment. 

The next best alternative to a radiant and geothermal systems is heat pumps (with high velocity mini duct system for distribution).  As with all forced air systems, if you take care of them, including changing filters regularly and caring for the air handler and condenser, they are great for heating, cooling and ventilation.

5. Ventilation: A good portion of our blog is devoted to ventilation, and we’ve come to the conclusion (as many building health experts have) that intentional, balanced ventilation in a highly sealed home is best.  It doesn’t matter whether you live in a pristine area with low humidity and pollution and prefer to open your windows most days; if pollen season or wildfire smoke or just cold winter air sets in, you will want to close your windows and still ventilate effectively!  For these reasons, it’s best to start with a tightly sealed home with dedicated, pressure-balanced ventilation installed.  Here are the features we would look for:

• Stale air is exhausted at the same rate fresh air is introduced into the home.  This will be 0.35 air changes per hour, but not less than 15 cfm (cubic feet per minute) fresh air per person (EPA.gov).
• Fresh air brought into the house should be filtered and conditioned (humidity removed or added and temperature adjusted) so that it’s not overloading the HVAC system and can be distributed to the home using only the air handler fan without need for the heater or compressor to run. 
• To be effective, fresh air can be continuous or run on a timed schedule every hour; it shouldn’t rely on a manual switch!
• Although there are situations that advocate for having separate ventilation and temperature control systems, in reality this creates redundant duct work.  An alternative is mixing conditioned outside air with the return air in the HVAC system in a mixing box.  
• An HRV (in non-humid climates) or ERV (in humid climates) optimize the exchange of energy between the intake and exhaust air. 
• In humid climates, a whole-house dehumidifier helps the HVAC system to keep the home at the right humidity without having to over-cool.
• Air quality monitoring for temperature, humidity and CO2 are the minimum variables but VOCs, CO and radon can also be added. 

6. Garage: Garages have become an extension of our homes because of their convenience for home access, ability to protect another very important investment (our cars), and for storage and hobby space.  However, not many people realize how garages impact the health of our homes.  You may know not to allow your car to idle while in the garage, but recent studies show that engines continue to emit benzene even after turning off the ignition.  Exposure to high levels of benzene over time can cause cancers like leukemia, and decrease red and white blood cell production.  “On average, benzene levels in houses with attached garages are three times higher than of other houses,” according to Deborah Schoen, the head of Health Canada’s indoor air section.  Therefore, we recommend that:

• homes with attached garages be sealed off from the garage with spray foam in the adjoining wall and ceiling
• Use ⅝” type X (fire-rated) gypsum board on the garage side of the walls and ceiling (if there is a room above), and use fire-rated caulk, adhesive, or expanding foam to seal up penetrations
• The door between the garage and house needs to be air-tight to avoid allowing hazardous gasses to leak into the home.  Install an insulated, metal, fire-rated door with a self-closing feature, so it won’t be left open accidentally.  A good weather seal is also imperative. (HGTV.com)
• Consider making the garage a negative pressure zone with an exhaust fan. 
• Always seal up paint cans, chemicals and fertilizer well
• Consider a detached garage or 3-sided carport

7. Wall and roof construction materials:  In the US, homes have been built with wood framing since our colonial days because it was cheap and plentiful.  Since then, we have been criticized for building with wood because of its weaknesses: fragility in storms and wildfires, its non-insulating properties, and susceptibility to rot and insects and mold.  Now, with lumber shortages due to the COVID-19 pandemic, wood prices are high and other products are getting due attention.  There are many traditional products that have mold-resistant chemicals added, but in general these chemicals may be as dangerous to those who are chemically-sensitive.  

According to Joe Lstibureck, an expert in home construction and insulation, the best place to locate the water, air, vapor, and thermal barriers is on the outside of the structure.  A “clever wall” combines all four of these layers in one layer.  Here is one way to do it:

If you need some points on building the perfect wall, roof and slab, check out this video and article!  Although it was written/filmed in 2010, it still holds true.  Building a healthy home requires that these layers are installed in the right order and connected to their counterpart on the wall, roof and slab.  

The following are some newer materials and methods for better insulation, weather and pest resistance than traditional wood framing.  Notice that any weather-tight cladding can be installed over them, although SCIP homes are typically finished in the concrete integral to the exterior of the panel.

• SCIP (structural concrete insulated panels) is a building system that resists earthquake, tornado and fire damage better than traditional wood framing.  It was innovated over 45 years in Austria by the EVG Company.  The walls are made with a structurally welded steel frame, which holds a layer of foam insulation.  The wall is then sprayed with 1.5” of concrete on both sides.  This “monolithic” construction is very energy efficient and long-lasting. New homes are constructed with custom-made panels, which reduce labor costs as well.  Here is a page showing SCIP construction.  RSG-3D panels are a form of SCIP construction.
• ICF blocks (insulated concrete form) have the insulation on both sides, and concrete is poured in the middle. With 2 layers of insulation, it can be between 4.8-12.7% more energy efficient than traditionally built homes, according to one study.  ICF blocks are made by different manufacturers, Nurdura being a notable one.  Nurdura offers several types of ICF which are manufactured to accommodate interior and exterior finishes, radiant heating/cooling, and a variety of wall designs.  The outer polystyrene acts as a vapor barrier, while the inner concrete acts as an air barrier.  
• SIP (structural insulated panels) are also pre-made panels, which have a sandwich of metal, OSB, magnesium-oxide, or plywood, with polystyrene in the middle.  They are made to support floor and roof loads. The SIPs are held in place with steel channels at the floor, sides and top, with screws that are common to metal construction. 
• Steel framing with cold-formed steel (CFS) is now cost-competitive since wood prices are higher.  Exterior insulation such as foam board can address the problem of thermal bridging, which is the conduction of heat through the steel frame.  This exterior insulation can provide all 4 barriers in one layer.

8. Flooring options:  Flooring can be a major source of VOCs and allergens, thus it’s important to make a healthy choice here. Hard flooring is preferable to carpet because carpet can harbor many allergens, but a HEPA vacuum can go a long way to keeping carpet clean.  Here are some materials in order of least VOCs, least allergenic and easy to clean, to more problematic. It is also important to check the underlayment and glues recommended to install your choice of flooring. (source: mychemicalfreehouse.net)

• Natural hardwood flooring with zero-VOC finish like tung oil
• Polished concrete
• Tile: marble tile, slate and concrete tile are all very safe options.  Ceramic and porcelain tiles should be tested for lead if the manufacturer does not give any warranties about it.
• Engineered wood with plywood base and zero-VOC finish
• Natural carpets: the best are made of wool or seagrass
• Synthetic carpets: PET polyester is very low in odor and off-gassing.
• Laminate flooring is generally low-VOC now, but look for GreenGuard Gold certification.  
• Cork flooring does contain binders but some are certified GreenGuard Gold.
• Bamboo flooring can warp, crack or split and contains quite a lot of resins or glues to hold it together.
• Vinyl planks and luxury vinyl planks are low-VOC, but do have “plasticizers” that have replaced phthalates.  

9. LOCATION: When moving into a new area, just like finding out how long it will take to get to and from work, it’s important to take time to study about geography, topography, windflows and potential pollution areas to know how they will affect your home.  We’ve written on how green space around your home can positively affect your heart health–so it’s best to buy in the greenest neighboorhood you can afford!  Conversely, less green places like cities with few parks and trees negatively affect heart health, because trees absorb pollution like ozone and fine particles, and reduce stress.  Then, there are the geological characteristics of the locale to take into consideration.   For instance, although California on the whole is a highly desirable state to live in, some pockets of California have terrible air quality because of geography.  In the San Joaquin valley, smoke from surrounding wildfires can get trapped for extended times, agricultural burning was practiced, and increasingly hot days cause ozone problems (pbs.org). This area feeds many with its rich farms and soil, but the migrant workers who harvest crops are most subject to the dangerous air quality.   Likewise, homes in the prevailing wind path of airports experience levels of ultra-fine particles (UFPs) that are several times higher than homes outside these areas.  Here are some other critical locations and situations to be aware of:

• a busy thoroughfare or bus station
• oil wells or refineries
• trash dump
• Chicken or cow farm
• Stagnant farm pond or standing water (like used tire recycling center)
• neighbors who burn trash or wood consistently
• farms that crop dust or use aerosolized fertilizers
• Areas that employ insecticide spray trucks
• Golf courses and other public areas that use copious lawn treatments
• Businesses that perform outdoor renovation work like sanding or spray painting
• Seasonal issues like wildfires, tree pollen, ragweed, etc.
• Neighbors who cook odorous foods, smoke, barbeque meat, have bonfires, etc. 

10. General air flow/floor plan: Traditional home design features defined rooms for living, dining and kitchen space.  In contrast, open floor plans have become quite popular in recent decades.  Open floor plans can create better cross-ventilation and air circulation, but we understand that life after the COVID-19 pandemic may require more walls, doors and private space in order to accommodate the many functions of working, learning and staying at home. (prnewswire.com)  Make sure that whether it’s time to throw open the windows or keep them shut, your floor plan works with natural or mechanical ventilation, instead of against it. Here are some aspects to consider:

• The number of house stories depend on style and space available to build. With multiple stories, ventilation becomes more complicated.  The “stack effect” of hot rising air is more pronounced with taller home height, and if air circulation from the bottom to top is unimpeded, this channel can provide significant cooling through ventilation.  The architect of an antebellum residence Longwood in Natchez, Mississippi, planned on this effect during design of the octagonal house that contains a basement and 7 stories above ground.  A center gallery was incorporated into each floor with doors to rooms and verandas on opposites side of the building, so that air flow was unimpeded through the outside doors and windows to the center galleries and up through the cupola of the home.  A modern home could incorporate a central courtyard for the same effects: natural light, cross ventilation, separation of spaces, and the psychological and physical benefits of plants and the outdoors. (fraherandfindlay.com)
• Layout of the home should not only consider views to the outside, but prevailing winds and penetrations such as doors and windows.  
• Types of windows are very important to ventilation. Casement windows are one of the top choices, as they can be opened fully for maximum ventilation.  Next, awning windows hinge at the top and provide the option of opening windows even when it’s raining.  If you live in a pollution-prone area, you may opt for double-hung windows, which can be opened vertically to allow the use of pollution-controlling window screens at the bottom.  Plus, you can allow cool air to enter through the bottom and warm air to exit through the top.  If your ceilings are tall, this effect is even more pronounced.  
• Ceiling height: if you have a large open space with high ceilings, it is either prime for a big fan to circulate cool air (see our post “What’s the deal with those big ceiling fans?” or skylights or high windows to exhaust hot air. 
• Location of the kitchen: The kitchen is still a source of heat and odors, so the placement of the kitchen and its exhaust vent hoods can assist in house ventilation.  Balanced exhaust hoods are a new design that pull air from the outside as well as exhausting heat and vapors, so that a strong negative pressure is not created in the home. 
• Hallways: Going back to past centuries, hallways were important to provide a private buffer for bedrooms, access to common washrooms, and ventilation.  The “dogtrot house” had a central hallway that separated rooms on either side, providing a breezeway and common area in the center.  Narrow hallways might be considered a waste of space, but with enough room, they can contain useful features like a sink to wash hands, concealed laundry, creative space, art display, etc.  (matthewjamestaylor.com)  
• The use of partial walls and glass can “define” space without limiting ventilation.  Where walls and doors are needed, such as bedrooms, consider the old-style use of transoms over doors, or in-door ventilation grilles. 
• Room use increases air circulation, because body movement and heat naturally causes the air within the room to move too.  Traditional homes may include a dining room that rarely gets used when the family eats in the kitchen, but by making such a room multi-purpose, the family gains access to more livable space. For example, you can create a bookshelf wall on one end with comfortable chairs, a large table that can serve as dining, craft or homework space, and mobile carts that can wheel away supplies or serve food when needed. 
• Furnishings: overcrowding a room with large furniture or using a room for dedicated storage creates air flow problems that can lead to mildew and poor air quality.  If possible, maintain spaces between furniture, and never cover an air vent with furniture (you can purchase “vent extenders” though). 

Well, those are some of our best suggestions for living comfortably and health-fully…only the sky (and budget) are your limits! 

Grilles, registers and diffusers: what they are and how to prevent condensation on them

I ran across the term “diffuser” while researching another topic and they were new to me in terms of ventilation.  When and where should they be used?  What is the benefit of a diffuser?  To start, let’s take a look at three similar products that have some overlapping characteristics and uses: grilles, registers and diffusers.   (source: jonite.com)

Grilles can be used on the intake (return) to HVAC systems, as well as the distribution.  They have fixed bars or louvers that don’t direct air as much as keep large objects from entering the ductwork.  They have no moving or adjustable parts.  A grille can also be placed in a door or wall to allow air movement between the two spaces. 

Registers are most likely what we grew up with in our homes: they are grilles with adjustable dampers.  The dampers can change airflow direction somewhat, or shut it off completely.  The typical rectangular register with flow damper is very common as a supply vent cover but is never used as a return (intake vent).

HVAC design can be somewhat complex, although many residential installers have simplified the systems to fit more homes with standard products.  If you really want the best performance out of your AC system, it’s time to look at diffusers.

When you need to distribute air evenly around a room, diffusers are the right choice, as the louvers and dampers are multi-directional.   Diffusers come in a multitude of shapes and designs to accommodate and hide ventilation outlets.  For example, InViAir has many different styles and sizes to accommodate design taste, lower noise (no one likes to hear the rush of air coming out of registers in a quiet room), and minimize condensation.  Diffusers can also be combined with lights so that they accomplish two functions in one unit, decluttering a space visually.

One problem home and business owners can encounter is water dripping from a vent and discoloring the surfaces below, and the ceiling itself.  There are many reasons a vent terminal can drip water, and it happens most often in the summer season.  Condensation is not just a problem of water dripping onto the floor or other surfaces; if the condensation continues, it can be a prime habitat for mold.  The condensation usually occurs because of one of two conditions: either the air in the room is too humid, or the supply vent is too cold. (energyvanguard.com) 

Here’s how to find out what is happening: check the room humidity with a humidity sensor like these that shows Temperature and Relative Humidity.  Then, go to a dew point calculator and input the room temp and relative humidity to get the dew point.  This is the dew point of the room after air has mixed in it.  Now, bring the sensor to the vent itself (carefully use a ladder if necessary.  Read the temperature of the air coming out of the vent.  If the temperature of the air coming out of the vent is at or below the dewpoint, the condensation is occurring because the cold air is hitting the warm, moist air of the room and water vapor from the room is condensing on the cold metal.  

There are two main solutions to prevent the condensation: reduce the relative humidity (RH) of the room (house) so that the dewpoint associated with the temp and RH is below the incoming air temperature, or increase the incoming air temperature.   Check out our post on a healthy home inventory regarding sealing the indirect leaks, direct leaks, attics, fireplaces and crawl spaces, before you go looking for smaller leaks such as doors and windows. 

How can you increase air temperature coming into the room?  According to energyvanguard.com, the two main causes of excessively cold vents are low refrigerant level and low air flow through the system.  An HVAC tech will need to check the refrigerant level, but here are the low air flow problems you can check:

• a dirty filter

• a filter that is too restrictive (higher MERV) than the system was designed for

• Blocking of return or supply vents by furniture, rugs, or other items

You can also ask the HVAC company to check that the cooling coil is not dirty, or that the ducts themselves are the proper size (I found out that the return air ducts in my home were too small for the system).  Here are some other remedies you can do yourself if you are not allergic to dust or fiberglass:

• If the duct above the vent has insufficient insulation or gaps in the insulation, then water vapor from the hot, humid attic air can condense on the duct and drip down into the room or on the ceiling around the vent.  You’ll need to go into the attic and bring some insulation, foil tape and knife or scissors with you.  Replace and seal all insulation gaps on the ductwork, all the way down to the ceiling (make sure the boot is properly sealed to the duct first; see the next point). 

• There are two components to the vent terminal: the boot (the part above the ceiling that connects to the duct) and the vent terminal, which is the grille, register or diffuser below the ceiling.  If these are not properly connected/insulated, then you can have condensation.  

• If the leak is between the boot and the duct, it should be sealed with a mastic sealer. If it’s between the register and the drywall, you can seal the leak using caulk. If you can’t find the leak, call a professional air conditioning company for help. (source: cooltoday.com)

• Condensation can occur on vent terminals when cold air coming out of the duct chills the metal of the terminal, and water vapor from the warm, humid air in the space condenses on the cold metal.  You can exchange a metal grille, register or diffuser with a plastic or composite one.  These diffusers by InViAir are made with a proprietary composite material that prevent condensation. 

It may take some time to prevent those pesky drips, but it’s worth it to avoid the mold!

Sealing Air Channels in Your Attic

Anytime there is a significant temperature difference between the inside and outside of your home, good air-sealing and insulation will pay dividends in energy savings, air quality and avoiding damage to your home.  If you don’t understand what an attic bypass is, this video gives a number of great examples.  The host discourages homeowners from doing their own air sealing, but the fact is that not all states require attics to be air sealed before adding insulation to the attic (unlike Minnesota).  Therefore, you may be hard-pressed to find a contractor in your area who is knowledgeable about doing this.  However, if you are physically agile and willing to put in some time and effort, it’s achievable!  

The best times to get up there and tackle air sealing in your attic is during a swing season when you’re not using your heater or air conditioner (it’s a comfortable temperature in the attic).  Also, do it BEFORE adding any more insulation (you don’t want to be digging through your new insulation to find these gaps!)

Don’t forget to dress appropriately!  You’ll need:

• Old clothes that can be laundered or thrown away, and a hat
• Vinyl gloves to keep the sprayfoam off your hands (it’s sticky and stains!)
• A headlamp if there’s not adequate lighting everywhere 
• A respirator to prevent inhalation of fiberglass and dust (it’s good to keep extra cartridges on hand)
• Safety glasses (because spray foam gets everywhere, trust me!) 
• Knee pads (because low attics require a lot of crawling!)
• Seal your cellphone in a ziploc plastic bag if you bring it with you (because spray foam gets everywhere, trust me!)

Here are some typical areas you will want to address:

Sealing Duct Shafts

According to Building America, a government program for testing and education about energy-efficient homebuilding, the proper way to seal duct shafts involves cutting a piece of plywood, rigid foam, or drywall to fit around the ducts, applying a bead of sealant like caulk to the supporting surface, fitting and securing the board with screws or nails, and applying more sealant around the inner and outer edges.  This is a great idea, except that caulk doesn’t usually cut it.  With the advent of spray foam in a can, it’s easier to get a good seal with spray foam than with caulk because the foam continues to expand for some time and will fill any voids.  

To seal gaps in and around ductwork, this video is great.  It shows several different types of repairs.  If you’re a novice, it might seem like you could just use “duct tape” on ducts, right?  Wrong!  Regular duct tape does not work well long-term on HVAC ducts.  It does not form an air-tight seal and over time, dries out and disintegrates.  That’s why you’ll want to use the following sealants instead:

• Using Air Duct Sealant (paste, also called mastic) and fiberglass tape or fiberglass cloth to patch small holes and larger gaps in ductwork (for a small kit, check here)
• Using spray foam to seal around ducts where they penetrate walls or unconditioned space like the attic or crawlspace.  There are different formulations in spray foam:
  • Small gaps less than 1”: try this one ($12/20 oz.)
  • Big gaps up to 3”, this formulation works well ($14 for 20 oz.)
• Use foil tape to seal around loose ends of insulation.  If there are any leaks in the ductwork, this will minimize air leakage in/out of the duct.  
• Check out our article on sealing your registers: you’ll want to do this to prevent condensation on the grilles and registers in your rooms!

I had an idea that my attic was leaky; I just didn’t know the extent of it until renovating for a new HVAC system.  I found a shaft used to hold ductwork that was open to the attic, but plunged down one floor and shared a wall with my bedroom.  This air space channeled hot/cold dusty air from my unconditioned attic right down the wall and it was NOT insulated.  

Because the shaft was rectangular and housed 2 round ducts in it, I decided to stuff some loose fiberglass around the ducts at the top and spray foam over them; the fiberglass only acted to plug large gaps and keep the foam from falling down the shaft before it hardened.  The only thing to remember is that the foam must contact solid surfaces, like foil-covered insulation, wood, or foam board, in order to make a continuous seal.  If I had left loose fiberglass sticking up out of the shaft, the air could pass right through it. 

Insulating Electrical Boxes and Can Lights

Here is something I’ve been wondering about for quite a while.  I have a number of electrical boxes for ceiling fans, lights and even the bathroom vent which are not sealed.  What kind of sealant should I use?  According to this short video (with happy music) by the EPA, spray foam comes to the rescue again!  As long as your fixture box doesn’t generate heat, you are fine with spray foam.  This brings us to can lights.  Foam and insulation must not come into contact with older style can lights (which use incandescent, halogen or another heat-generating bulb) because of fire risk.  In this case, you’ll want to purchase a can light cover with fire rating specs in order to safely insulate the area around the light.  It can be sealed with spray foam around the bottom perimeter of the cover to the sheetrock.  Again, you do not want to let the spray foam contact any part of the can light, which can get very hot, so be sure to hold it down to the sheetrock when spraying, and minimize any holes necessary to accomodate electrical wires going to the light.  

It’s also recommended to plug holes drilled for electrical wires through the top plates of your walls (typically these are wood 2x4’s or 2x6’s).  If your local code requires that these penetrations be sealed with a fire retardant sprayfoam, then Great Stuff Fireblock with smart dispenser ($10) will work. 

If you want to keep your heating and air conditioning system working well, prevent mold and moisture damage, lower humidity in your home as well as lower energy costs, tackling air sealing in your attic is a must!

How’s the air quality in your laundry room?

To be honest I hadn’t thought about this one before…it usually smells nice inside when I’m doing laundry (because of scented laundry products), and it smells nice outside too, because of the scent coming through the dryer vent!  Our brains are trained to equate nice smells with fresh air,  but read on to find out exactly how good this air really is.

For some years now, we’ve known about microfibers from clothing that get washed out into waste systems, streams and rivers, eventually ending up in the ocean, marine life and even tap and bottled water.  But recent research shows that an even higher quantity of microfibers are being released to the air through dryer vents over those that are washed down the drain.  These microfibers are in the fine to ultra-fine particle range, and contribute to overall outdoor air pollution.  This, in combination with the VOCs emitted with the laundry products* is not good.   Although the researchers found that smaller pore size on the dryer lint filter as well as use of a single to double-dose of laundry softener reduced the outdoor emissions, a lot of microfibers are still being released into the air.  All of my training at HypoAir led me to think, if that much is going outside, how many particles are going into the air inside?  Fine and ultra-fine particles are a hazard to our respiratory system and whole bodies (see our post “What are ultrafine particles and where do they come from?”).

Since we at HypoAir are not going to advocate for using commercial laundry softeners (one softener used in the study was Bounce, which receives grades of “C” - “F” at EWG.org), here are some of the other ways you can reduce fine particle pollution in your home and outdoors:

• Use non-toxic detergent strips and laundry pods to reduce VOCs.
• Use spot cleaning and other methods to keep your clothes fresh,  to reduce washing.  
• Dry clothing outside when and where possible to avoid release of microfibers
• For washing: GuppyFriend and Cora Ball catch microfibers before they are washed down the drain (GuppyFriend also prevents fibers from breaking off your clothing). Or, install a microfiber filter from Girlfriend Collective on the drain 

Microfibers are just one part of the air quality problem emanating from laundry rooms.  Other parts include the carbon monoxide (CO) emitted from gas dryers as a byproduct of combustion, and water vapor from all dryers as the clothes dry out.  Dryer vents are meant to exhaust all of these safely outside–if they are sealed tightly.  Here is the proper way to seal a dryer vent from the machine to the wall:

• Don’t use duct tape!  Despite its name, the adhesive on duct tape is not suited for dryer vent use.  It can dry and crack over time, causing leakages. (source: bestairducts.com)
• Do not use screws to connect sections of ductwork together because the sharp end can catch lint inside the duct. (dryerventwizard.com)
• Use foil tape to seal each joint of the ductwork. Here is a video showing how to apply foil tape.
• To install a dryer in a new place, here is a more in-depth instructional on how to run the dryer vent line. 
• Make sure the vent is properly sealed to the exterior wall.  Here is how to reseal a vent to the wall.  
• Do not terminate the duct in an attic or crawlspace!  It must go directly outside.  

If you run the dryer with a load of laundry and you feel that the humidity is appreciably increasing in the room, it’s best to investigate for leaks in the dryer vent line as soon as possible, because that means that microfibers, water vapor, and possibly VOCs and CO are coming into your living space.  The dryer vent is meant to be a low-pressure line for exhausting these products.  Another cause of malfunction is letting dryer lint build up in the line, which causes higher pressure (if this happens you may also notice your clothes are not drying as quickly).  The dryer line should be cleaned once a year, so that lint does not build up and cause a venting problem or fire hazard.

Finally, here are a few “upgrades” that can make your laundry room an area of good air quality instead of a hazard:

• Since the washing machine, wet laundry and dryer heat all combine to add more humidity and heat in this room, consider installing a separate exhaust fan in your laundry room to run while doing laundry.  
• Plug in a Mold Guard/Germ Defender in your laundry room to mitigate mold from increased humidity, PM2.5 from microfibers/lint, and VOCs from laundry products.

With some inspection, planning and improvements, your laundry room can be a more healthy place!

Micro- and Nanoplastics are everywhere

Children especially are moved with compassion for animals.  I remember learning as a child that non-biodegradable plastic often ends up in the ocean, and sea animals like birds and fish can get entangled in plastics like 6-pack rings, so I started to cut apart the rings before throwing them away so that the animals wouldn’t strangle.  Later I learned that some plastic bags were being manufactured as “biodegradable”; this was some relief to my mind.  However, the newest question is, into what are they degrading?   It turns out that plastics are coming back to us in invisible ways when they break down into microplastics and nanoplastics.

Microplastics, artificial polymer particles with size less than or equal to 5 mm, were initially reported in 2004 (2022 study: Nanoplastics and Human Health: Hazard Identification and Biointerface).  They are produced from disintegration of plastic products, from the ubiquitous plastic shopping bags to a child’s toy stroller to an empty jug of laundry detergent. Small millimeter-sized pieces of plastic seem like they would produce a lot of plastic “sand” that could be filtered out of water or even pass through our digestion system unchanged.  Yet microplastics are not the end product; nanoplastics are.  Nanoplastics are particles with a size ranging between 1 nm and 1 μm, which cannot be seen by the human eye.  

Nanoplastics come from a lot of different sources and some surprising ones.  We’ve written about different harmful nanoparticles that can be emitted into the air and water: from ceramic coated cooking pans, 3D printers, dust particles, from combustion engines, graphene, household cleaning products, and microfibers that get released in your washing machine and dryer (some of which are actually nanoplastics).  Here’s a new one to us: huge amounts of nanoplastics are released by car and truck tires every year by the simple acts of driving and braking.  

According to National Geographic, “Tires are actually among the most common plastic polluters on earth. A 2017 study by Pieter Jan Kole at The Open University of The Netherlands, published in the International Journal of Environmental Research and Public Health, estimated that tires account for as much as 10 percent of overall microplastic waste in the world’s oceans. A 2017 report by the International Union for Conservation of Nature put that number at 28 percent.”

“Today tires consist of about 19 percent natural rubber and 24 percent synthetic rubber, which is a plastic polymer.”  Considering that each (car) tire will lose about 1.5-2 lbs of weight over its lifetime, which is the wear of rubber and plastics from it, millions of tires on our roads add up to tons of micro- and nanoplastics.  

Nanoplastics are dangerous to the environment and to us.  The following diagram shows the many ways our bodies are exposed to them:

How to protect your child’s air quality

When school shootings, abuse or other violence take up the bulk of the news, it’s easy to miss that the very air your family breathes has a great impact on childrens’ health (even more than ours).  Why? (from lung.org)

1. Air pollution can affect them even before they’re born, with increased chance of pre- term birth (California study published in 2016)
2. Eighty percent of a child's lungs will develop after birth, and continue development until the child becomes an adult.  Air pollution increases the risk that their lungs will not reach full maturity. 
3. They take 2-3 times as many breaths as adults.
4. According to a 2021 meta-analysis from Harvard T.H. Chan School of Public Health, exposure to fine particulate air pollution (PM2.5) has been linked with significantly increased risk of autism spectrum disorder (ASD) in children, particularly if exposure occurs during the third trimester of pregnancy or during early childhood,
5. They spend a lot of time in schools that may have inadequate ventilation and high contaminants.
6. They don’t behave like adults–they spend a lot more time outdoors with increased activity.

Protecting your child’s lungs and body from polluted air is not always easy.  Masks can help, but they’re just one part of your arsenal.  

Masks need to have good filtration, fit and comfort.  AirPOP is a company that was founded when the children of one of the founders suffered from acute respiratory reactions to the local air pollution in China.

When choosing a device for your child, make sure to choose one that has undergone some lab testing against fine particles or is officially certified as KN95, N95, KF94, FFP2, or another regional standard. For air pollution, cloth masks and surgical masks provide minimal protection. (airpophealth.com)  Here is one of the highly rated KN95 kids’ masks from their collection.

In moderate to severe air quality environments, it also comes down to monitoring your children’s whereabouts and activities.  Teaching them about air quality conditions and forecasts lets them know why they are wearing a mask or doing activities indoors, and every parent knows that the “Why?” is very important!

Whether it’s walking, riding a bus or driving them in your personal car, getting your children to school can expose them to a lot of pollution.  Finding less polluted routes or using a mask or HEPA filter in the car makes sense.  

At school, teachers need to know the outdoor air forecast in order to plan outdoor time or alternative indoor activities.  Also at school, you can inquire about whether they have an Indoor Air Quality (IAQ) monitoring plan. If not, the EPA has suggestions on how to develop and implement one.

At the end of the school day, idling busses and cars (in the car pickup line) can be a problem as the vehicles queue up and wait for their passengers and the scheduled time of departure. According to the EPA, it’s a myth that busses need to remain idling to keep the cabin (inside the bus) at a comfortable temperature.  There are technologies available to avoid idling and strategies to help parents and schools implement anti-idling policies. 

Children love to learn. Learning eventually gives them power over their environment through the ability to make wise choices.  They are also naturally fond of the earth, our natural environment, and their ability to do physical activity (read: play!), so that educating them on air quality can be done on age-appropriate levels with fun activities.  Here are some sites to help:

• Activity book and fun facts

• Elementary school lesson and activity plans

• Fun air quality experiments for different grade levels

Getting your child “on-board” with protecting their air quality will come in time, but until then, there are daily decisions that parents need to make that will impact their life and health for years to come.  Don’t worry, HypoAir is here to help!  Consider adding an Air Angel and HEPA filter to their bedroom to cut down on fine particulates, germs and allergens.  For a whole home solution, our Whole Home Polar Ionizer and HVAC home filters protect through your HVAC system.   These are low-maintenance ways to take the burden of air quality off your shoulders at home!

The Epidemic of Asthma

If you don’t suffer from a certain disease or know someone who does, it can often evade your concern or thinking.  Asthma is one such disease for me, and aside from drug commercials on the internet and TV, I didn’t give much thought to it.  “Pandemics” seem to have taken over our health radar, while asthma continually advances in cases every year. 

Asthma is a chronic disease that causes airways to become inflamed, making it hard to breathe. Although it is incurable, asthma can be managed so that it doesn’t recur by avoiding triggers, taking medications to prevent symptoms and preparing to treat asthma episodes if they occur. (aafa.org) About 300 million people worldwide have asthma, with projections for it to increase to another 100 million by 2025 (The Global Asthma Report, Auckland, New Zealand, 2018). 

According to Oxford Languages, an epidemic is “a widespread occurrence of an infectious disease in a community at a particular time.”  Asthma is not an infectious disease, yet it is called an epidemic because of the sharp increase of cases since the 1960s in many developed countries.  This sparked a number of studies in the 1990’s, confirming that “asthma is one of the most common chronic diseases across the globe in all age groups and there is substantial variation in asthma prevalence worldwide.”  (2019 study on the Epidemiology of Asthma)  It is difficult to define, but the research community finds it helpful to define it by observable traits (phenotypes) which are composed of symptoms (such as wheeze or cough) and objective measures (such as lung function and biomarkers in blood, exhaled breath, sputum, and/or urine). 

What causes asthma?

Researchers prefer to use the word “trigger” instead of “cause”.  However, some of the airborne triggers are House dust mite (HDM), Animal hair and dander, Pollen exposure, Mold (fungal) spores, and  Thunderstorm asthma (most prevalent in Australia where high pollen counts are released during a unique type of thunderstorm).  Habits like parental or personal smoking tend to increase risk for asthma.  Occupational triggers such as cleaning agents, paints, or dust may increase risk (a comprehensive list can be found here), and there seems to be genetic predisposition for it also. 

According to the Asthma and Allergy Foundation of America (AAFA), asthma tends to peak in September in the US due to a confluence of several risk factors.  This month peaks in ragweed pollen, a common fall allergy; more falling leaves mean more mold spores in the air, and the return to school causes more respiratory illness in families. In particular, the third week of September is usually the highest in numbers of doctor visits and hospital stays due to asthma attacks, and children are the most affected.  (aafa.org)

Asthma is a problem in children because their lungs are still developing, and continue to develop until they become adults.  Asthma may impair airway development and reduce their maximum lung function, and these deficits may persist into adulthood.  When occurring first in adults, asthma may accelerate lung function decline and increase the risk of fixed airflow obstruction, especially for smokers with asthma.  People with asthma are more susceptible to infections and non-communicable additional chronic conditions (comorbidities) such as diabetes, osteoporosis, metabolic syndrome, cardiovascular diseases, and issues with mental illness such as anxiety and depression. (2019 study)

Asthma can’t be cured, but it can be controlled.  It’s controlled through avoiding triggers, and/or the use of medication.  Because avoiding triggers could be potentially be better for your body and your budget, here’s some advice on how to do that (adapted from mayoclinic.org):

• Use air conditioning to establish a clean, comfortable environment in your home.  Air conditioning allows you to control:

• Humidity: most sources set the optimal humidity between 30-50% (if it goes well above that, use a dehumidifier).  At this range, dust mites are lower in concentration.

• Pollen: with air conditioning, you’re able to close the windows on high-pollen days

• Use filtration to keep airborne contaminants low!  You can do this by regularly changing your HVAC home filters (and possibly increasing the MERV rating on them), or adding a standalone HEPA filter to one or more rooms in your home.  In addition, bi-polar ionizers like our Germ Defender and Whole Home Polar Ionizer will cause larger contaminant particles to clump together and be more easily filtered or vacuumed.

• Clean your home regularly, once a week, with a HEPA vacuum cleaner and non-toxic all surface cleaner like TotalClean.  If you can’t keep your home clean by yourself, ask someone to help you.

• Prevent mold from growing in your home by monitoring wet areas like bathrooms and under sinks.  Mold can also intrude if you don’t clean gutters or remove debris from around the house on a regular basis, so try to keep your gutters and the area directly around your home clean too.

• Keep pet dander under control by brushing pets outside and bathing them regularly with a moisturizing shampoo.

• Remove hard-to-clean surfaces like carpet and deep rugs, and avoid down-filled pillows and furniture. 

• Consider avoiding perfumes and heavily-scented personal products, candles and cleaning products.

• Because cold air can trigger asthma, cover your mouth and nose when you go outside in cold temperatures.  

In addition, since asthma can be exacerbated by excess weight and heartburn, it’s important to take care of yourself with moderate exercise (your doctor can help with advice) and medication if acid reflux is an issue.  

If you are among those who deal with asthma on a regular basis, remember that surrounding yourself with a clean, comfortable environment can be the best investment in your health and life.  Changes like removing fragrances and adding an air purifier can make a big difference in the way you feel.   You are definitely your best advocate in minimizing the effects of this disease!

Can I avoid mold with JUST ventilation?

Here’s the spoiler: many times you can, sometimes you can’t, but read on to find out more!

This post was borne after reading a very interesting article in The Atlantic.  The author lives in an area of coastal Japan, which is dry and beautiful for ten months out of the year and very humid for the two months of summer.  During the two humid months, he struggled with mold growth in his home and tested dehumidifiers, air conditioners, and finally fans and open windows.  When he used the fans to find the perfect amount of ventilation, the surfaces stopped forming fuzz overnight and his shoes stopped smelling like loaves of bread.  He also pointed out that according to research, he was much less likely to get sick from coronavirus or any other airborne disease with fresh air constantly diluting the rooms.  I wanted to know, is good ventilation the number one key to avoiding mold problems?  Is it possible to live healthy with only fresh air ventilation?

First of all, we are very accustomed to living in air conditioning.  It may not always be needed, but it’s everywhere: the office, the grocery store, the gym, school, and of course, our homes.  Except in select areas of the US, homes without air conditioning are even viewed as less valuable.  

Is your climate temperature livable without air conditioning?  Considering that the US was settled before the advent of air conditioning, then the answer is mostly yes.  Of course, there are the desert areas like Las Vegas where extreme temperatures would make it very difficult, if not impossible, to live year round.  The cement and asphalt of the city make it hotter today than it was during its historical roots, but on the day of the famous land auction which settled Las Vegas, men were standing outside in 110 degrees in wool suits, which means nowadays we have adapted ourselves out of the outdoors and into air conditioning. 

Then, we have humidity.  High humidity combined with high temperatures, as we describe in this post, impedes evaporative cooling of our bodies, to a point that 95 degree wet-bulb temperature is the maximum limit of temperature and humidity.  If the climate increases beyond this (as it has for periods in India and other areas), mechanical cooling like air conditioning is necessary.  

Then, we have pollution.  Outdoor pollution from vehicles, airplanes, industry and a slew of other sources sometimes necessitates closing off our homes and filtering air coming in for breathability.  

These are some of our human limits of comfort and endurance.  But if air temperature, humidity and outdoor air quality would allow us to live without air conditioning, do our homes need it to avoid mold and be healthy?  If not, what is the upper limit of humidity, such that good ventilation can keep mold in check?

There are different climates in every state in the US, and many of them are perfect for living without air conditioning.  Southern California and Hawaii come to mind, for example, but according to AprilAire, Hawaii is in the top 10 most humid states!   Here they are in order of decreasing humidity:

1. Alaska

2. Florida

3. Louisiana

4. Mississippi

5. Hawaii

6. Iowa

7. Michigan

8. Indiana

9. Vermont

10. Maine

Looking at this list, 4 out of 10 (Alaska, Michigan, Vermont and Maine) are among the most northern states, yet they are also among the most humid!  Temperature-wise, homes in these states don’t need air conditioning for many days during the year, if any.  Yet we know that humidity is a big factor in maintaining healthy air, so how is it possible to keep a healthy home in a humid environment without air conditioning?  

Ventilation is the primary key.  According to the Air Infiltration and Ventilation Centre (AIVC, an international organization), ventilation is “the process by which ‘clean’ air (normally outdoor air) is intentionally provided to a space and stale air is removed. This may be accomplished by either natural or mechanical means.”  For our purposes, we will discuss the distribution and quantity of that fresh air.  If the ventilation system delivers the right amount of fresh air, but does not circulate it throughout the home efficiently, then most of the home can be stale and ripe for mold growth.  If the distribution is right but not enough fresh air is introduced, indoor contaminants are not diluted.  To put it succinctly, in many homes, distribution AND quantity of fresh air are lacking.  Let’s look at them individually.

Distribution

We’ll look at distribution first, because it often determines how the fresh air comes in.   If you live in a naturally pristine area like the coast or country where you can leave your windows open or cracked for most seasons, this is an ideal way to bring in fresh air.  In this case, check into installing a whole-house fan, which will pull air from every cracked window and exhaust it through a vent in the roof or attic.   This page describes the use of a whole-house fan, including the recommended air flow for specific climates like coastal, desert, mountain or inland.  Such a fan is recommended because it takes the guesswork and legwork out of setting up ventilation scenarios for each room of your home.  In order to be able to leave windows open for extended periods even during rain or allergy season, check out these adjustable screens, which filter out most pollen, 95% of rain and 69% of UV rays.  

If installing a whole-house fan is not possible, then you’ll need to experiment with portable and ceiling fans in order to get that fresh-air moving throughout each room.  Open windows and doors across the house to get cross-ventilation, and try to direct the flow from the cooler to the warmer sides of the house to exhaust hot air.  Although it may take more work to set up, a manual ventilation system can be just as effective as a whole-house fan if used continuously.

• Ceiling fans are a low-cost way to keep air from becoming stagnant in any room. 
• Portable fans can be set up in windows: 
  • Box fans are low-cost but they will need to be moved and windows closed every time rain may threaten. 
  • New window fans are smarter:
    • The EcoBreeze 2, $229, has a built-in filter, temperature sensor and humidity limit so it will bring in fresh air whenever the temperature and humidity outdoors allow.
    • Bionaire Window Fan with Twin 8.5” Reversible Airflow Blades, $70, has a water-resistant motor so that light rain won’t bother it.
    • Lasko 16” Reversible Window Fan with Storm Guard, $120, allows you to close the window without moving the fan for those really big storms.

At HypoAir we always recommend maintaining a humidity of 40-60% in your home in order to keep mold and germs at a low level.  I went back to a study performed before the widespread use of air conditioning in homes, in order to find out how they prevented mold in the “olden days”!  An extensive experiment conducted over one year and published in 1953 showed that the amount of mold that grows on a substance depends on the nature of the substrate (material) and the relative humidity (RH) in the air above it.  Leather, cheese, wool cloth, wood, cotton cloth, and glass wool (like fiberglass) were tested in sealed environments of different equilibrium humidities.  It was found that:

• “In humidity tests of one year's duration, leather and cheese were susceptible to growth of mildew at 76 per cent R.H. and higher; wood and wool mildewed at 85 per cent R.H. and greater, while cotton cloth and glass wool failed to mildew at 92 per cent R.H. but mildewed at 96 per cent and 100 per cent R.H.” 
• An atmosphere of 65% RH or less “might be considered safe for permanent storage of all materials (studied)”.
• “...molds obtain their moisture directly from the substrate rather than from the moisture in the air…The minimum humidity for the occurrence of mold growth was related to the equilibrium moisture content of each material at each humidity…”
• “It is concluded that the water-absorbing properties of the substrate play an all-important role in determining the limiting humidity of the atmosphere at which mildew will occur. It is postulated that the fungus is incapable of obtaining moisture for mycelial development directly from the atmosphere (except at 100 per cent R.H.) but derives it from the substrate which obtains the moisture from the atmosphere.”

In layman’s terms, each substance (leather, cheese, cotton cloth, etc.) had a different minimal humidity at which mold grew.  The substance absorbed water from the air, and the mold spores took their nourishment from the water in the substance and the food in the substance. If the humidity in the air was kept low enough so that the substance could not absorb the minimal amount of moisture for mold growth, no mold would form on it.  This experiment did not employ any ventilation, so we will go into that next.

How did our ancestors keep the humidity in their furnishings and clothing down when the air coming in from the outside was humid?  Ventilation is still the answer.  Ventilation helps evaporation, which lowers the moisture content of the substance, and here is how.

Evaporation is the movement of water from its liquid form (in the substance) to its vapor or gaseous form, that we call water vapor (serc.carleton.edu).  Evaporation is influenced by temperature, relative humidity and wind.  Higher temperature = more evaporation. (Evaporation rates are higher at higher temperatures because as temperature increases, the amount of energy necessary for evaporation decreases, and higher temperature air can hold more water vapor.) Next, higher relative humidity = less evaporation. (The more humid the air, the closer the air is to saturation, and less evaporation can occur.)  Finally, more wind = more evaporation. (Wind moving over a water or land surface can also carry away water vapor, essentially drying the air, which leads to increased evaporation rates.)  Therefore in a house, hot dry air circulating is great for preventing mold, but generally on a summer day we can get 2 out of 3: heat, higher humidity, and circulation.  

Here is a more detailed explanation of how air circulation helps evaporation: “Evaporation increases the humidity of the atmosphere that immediately surrounds the liquid. This humid air takes some time to dissipate into the rest of the atmosphere. The presence of a breeze, a powerful wind, or some other form of air circulation can speed up this process and make the environment of the liquid less humid. Therefore, by decreasing the humidity of the liquid’s surrounding, a powerful breeze or wind can increase the rate at which the liquid evaporates.”(bjyus.com)

This leads to the conclusion that the RH of the air can differ from RH of the substrate.  Scientists have devised a different term for RH of the substrate, calling it water activity, aw, which is expressed as a decimal, or equivalent relative humidity “ERH”, which is expressed as a percentage.  (We’ll stick with ERH in order to compare it directly with RH of the air.)  ERH is equal to RH at the surface of the material only when the system is confined to the extent that the atmosphere above a moist surface is at the same vapor pressure and temperature as that directly at the moist surface. This is called a “steady-state”.  In actual environments, however, there is usually a gradient of vapor pressure from the surface into the air above or vice versa. Since RH =partial pressure/vapor pressure x100%, and vapor pressure in the atmosphere is variable, this means that RH is constantly varying throughout a room.   This means that ventilation, which affects vapor pressure at the surface of the substrate, affects relative humidity of the air contacting the substrate to determine the ERH (the moisture content of the material). 

In a more recent (2019) study on ventilated insulation panels for housing, ventilation channels are shown to intensify removal of moisture from insulation, meaning that ventilation dried the insulation: “...even with a high humidity of the indoor air of about 70%, the relative humidity of the air in the material of insulation did not exceed 50%, which provided high heat-protected properties of the panels.”

A second recent (2020) study of homes in the UK found that higher concentrations of mold, and thus more “moldy odors” are found in bedrooms rather than living rooms.  There are several reasons for this, even though the average humidity in both rooms was very similar.  The presence of more people in living rooms naturally causes more circulation of air in living rooms.  Also, the presence of large pieces of furniture such as wardrobes and beds placed near walls in the bedroom impedes circulation of air.  Thus, circulation of air was implied to lower the mold concentration in the living room over the bedroom.

According to Cleaning and Maintenance Management, a property restoration company, here is how we can understand the drying process: “Low relative humidity (RH) is necessary for drying, as moisture in materials and air seek equilibrium. The lower the RH of the air, the quicker the wet materials will give up their moisture to become equal with the moisture in the air. …Air movement is the workhorse of drying by displacing high RH at the surface of wet materials with lower RH. Circulation airflow moves wet air to our dehumidification systems (either mechanical or ventilation), allowing us to manage RH and water vapor in the air. 

Next, we’ll explore how the quantity of fresh air to bring in is determined by the advised minimum, and by temperature.

According to the EPA, ASHRAE  (formerly called the American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends (in its Standard 62.2-2016, "Ventilation and Acceptable Indoor Air Quality in Residential Buildings") that homes receive 0.35 air changes per hour  but not less than 15 cubic feet of air per minute (cfm) per person. 

Too much fresh air can be bad in hot, humid climate, because heat increases the amount of moisture air can hold.  A 2013 study showed that in very humid climates (like Bangkok, Thailand), reducing ventilation to the minimum (by ASHRAE) reduces indoor mold formation.  This is due to the fact that bringing in air from outdoors that is greater than 70% humidity, increases humidity inside.  This is not the case in a lower humidity climate like State College, PA, where they conducted a similar experiment: indoor humidity did not increase above 70% because outdoor humidity was not high. 

Too much fresh air can also be bad in cold climates, because bringing in cold air can cause condensation.  A study in Sweden showed that in cold attics where insufficient sealing caused warm air to leak through the upper ceiling into the attic, traditionally vented attics allowed too much fresh cold air into the attic and caused condensation on the underside of the roof, resulting in mold and rot.  “The optimal air exchange rate varies with the outdoor climate, and fixed ventilation through open eaves and/or gable and ridge vents is not always the best choice. To get optimized ventilation regardless of type of external climate, attic insulation, airtightness, etc., ventilation must be controlled and adapted to the present situation. By using sensor technology and mechanical ventilation and making the attic as airtight as possible, this can be achieved.... A basic system would comprise mechanical fans and dampers controlled by attic and outdoor climate sensors installed in a sealed attic without vents. The ventilation system runs only when the outdoor air has a potential to dry out the attic.”

In the article “Ventilation won’t prevent attic mold growth” by Jeffrey May, Founder and Principal Scientist of May Indoor Air Investigations LLC in Tyngsborough, MA, various attic situations with ventilation showed mold due to warmer air leaking into the cold attic space from the home below, causing condensation.  These were usually mediated by sealing the attic floor better (for example, sealing the attic stair access and older can lights) or converting the attic to a conditioned space by sealing it off from the outdoors and providing more insulation. 

In the basement, EZBreathe is a product that operates on sensors to draw humid air out of the basement, ventilating with less humid air from the upper levels of the home.  Although we generally advocate for a balanced ventilation system instead of the slight negative pressure generated by EZBreathe, it does work to keep the basement area at a lower RH than it would have by just opening windows. 

A 1993 study showed that in an apartment in Japan, fungal indices were the highest in the corner where the northern and eastern walls faced outdoors.  This is because these walls were colder (they faced away from the sun), causing higher relative humidity inside the room.  This cautions us to pay special attention to rooms on the north side of your house.

In these five insulation, attic, basement and home situations, sensors in each space can be useful to know how much outside air to bring in according to the conditions in that space, in order to avoid mold.  According to the EPA,  “Mold and mildew growth can be reduced where relative humidities near surfaces can be maintained below the dew point.

The best way to explain this (per this great article) is to find out the dewpoints of the indoor and outdoor conditions.  If the outdoor dewpoint is lower, you can ventilate with fresh air and still dry out your house!  For example on July 26, 2002, here are the conditions inside and outside my house (a relatively “dry” hot day outside!):

Inside: 76 deg F, 67% humidity = 63 deg F dewpoint (dpcalc.org)

Outside: 91 deg F, 54% humidity = 72 deg F dewpoint (dpcalc.org)

See, even though the relative humidity outdoors is lower, if I open my windows, that hot air coming inside would be cooled and relative humidity would increase, working against my humidity goals.

Mold is not the only byproduct of high humidity in our homes.  Dust mite fragments and excrement are a main allergenic component of household dust, and dust mite populations increase when more humidity is present (1996 study). “Laboratory studies of D. pteronyssinus suggest that optimal conditions for growth and development occur between 70% and 80% RH at 25°C, with acceptable ranges of 55% to 80% RH and 17°C to 32°C (Anderson and Korsgaard 1986).”  Mites ingest water directly from water vapor in the air through special glands. 

In addition to distribution and quantity of fresh air, a minute amount of temperature control in colder climates makes a big difference.  Mechanical ventilation can actually keep indoor humidity lower than the outside air it brings in if the temperature is raised slightly.  Cold foggy air has a high RH.  However, if you warm up that same air, the relative humidity drops because warm air has a higher capacity to take moisture.  Even on a cold, foggy day, you can fill up the house with 100% humid air, warm it up and have much less than 100% humidity inside the house. 

Finally, we have a device that our ancestors did not have in fighting mold and mildew: bipolar ionization.  From personal experience, adding a Mold Guard/Germ Defender unit to a small humid space like a bathroom or laundry room essentially eliminates mold formation, even if the ventilation does not keep the moisture content of the towels, wood and surfaces below what inhibits mold formation.  The positive and negative ions constantly destroy mold spores and inhibit mold formation.  An Air Angel can provide the same protection on a slightly larger scale (up to 300 ft2).  On the largest scale, a Whole Home Polar Ionizer installed in the HVAC system distributes these ions to every room and destroys mold spores throughout the house.   

So, the interesting takeaways from these studies on ventilation let us know that in many cases we can control mold without air conditioning, as long as we pay attention to:

• ventilation distribution, which is the distribution of incoming air to every space and velocity of air within the space.
• Ventilation fresh air quantity, which is the amount of outside air to bring in
• Temperature, which can affect evaporation and condensation
• Use of a BiPolar Ionization device.

Knowledge about how mold forms is a blessing that we can use to deter it!

Scent Control for Hunters

If you are a hunter, you’ll likely know that many animals have a much more sophisticated sense of smell than humans, giving them information about how to stay alive and out of our paths.  Eliminating human scent, then, gives an edge to the hunter, allowing his prey to come closer or linger a few more seconds.  There are many products marketed to hunters, but if you’re in the know, they don’t have to be expensive or hard to find!  In fact, some are already in your pantry or backyard…

First of all, hunting is not like watching sports.  Although traditionally it is “unlucky” to wash a certain item of clothing if your team wins (tradition says you should never wash it), doing this in hunting is a sure way to tip off your prey, because human scents like sweat, gunpowder and gasoline are big warning signs and build up with wear!  So, into the wash go the hunting clothes…but not just with any laundry detergent.  Artificial scents and whiteners are pungent “stay-away” clues to them.  Particularly, three studies in 1992, 2013 and 2014 on deer eyes confirmed several theories about their visual abilities: (When deer eyes can see laundry detergent residue, hunters must work hard to stay hidden)

• With just two types of color photoreceptors, deer eyes distinguish fewer colors than human eyes, which have three types of color detectors.
• With a deeper perception of blues into the ultraviolet range, deer see not only blue jeans but residue from UV brighteners in laundry detergent that is invisible to humans.
• Deer pupils gather more light, and a greater concentration of light-dark photoreceptors gives them better night vision. Eyes positioned on the sides of the head give deer a broader field of view.
• Deer have incredible motion detection. They can see a hunter blink from a distance, but if there’s no additional movement they don’t know what it is.

Similarly, a deer’s sense of smell is hyperactive compared to ours.   Biologist Dr. Bronson Strickland of Mississippi State University’s Deer Lab describes “scent” as a generic term for volatile organic compounds (VOCs) which are given off by a subject. Due to their high vapor pressure, these lead to large numbers of molecules evaporating into the surrounding air.  (The Science Behind a Deer's Sense of Smell & Scent Control)

VOCs can come from numerous sources, like manmade products such as gasoline, diesel fuel, paints, oil, tar and perfumes. Our bodies give off thousands of VOCs: our organs such as the liver, kidneys, lungs and skin all take toxins from normal metabolism and render them into removable chemicals, through excretory pathways found in feces, urine, breath, sweat and saliva.

Here’s where a deer has the upper “hand”: any of these “human” scent molecules are inhaled through its broad nasal openings and then captured by little hair-like cilia in the mucous membrane. Once captured by the cilia, VOC molecules dissolve into the mucous and are transferred to the olfactory epithelium.  The whitetail epithelium is reported to have 297 million olfactory receptors. (The human epithelium has only 5 million.) These receptors translate the scent signal as electrical impulses up through nerves that extend through the roof of the mouth and into the part of the brain known as the olfactory bulb.  In another study, it was demonstrated that a whitetail’s olfactory bulb is about four times larger than that of a human. This means deer have a greater capacity to both detect and transmit scent signals to their brains. The olfactory bulb then shoots electrical impulses up the olfactory nerve into the limbic system of the brain for analysis.  The longer a deer has lived in the wild, the more the deer has learned from experience that certain VOC signatures signal danger.   (The Science Behind a Deer's Sense of Smell & Scent Control)

Since hunters strive to be invisible to their prey, then, the main goal is to avoid emitting as many of these VOCs as possible.  We’ll go them here one by one; one of the cheapest natural deodorizers is baking soda, and you can use it in your laundry, on your teeth and sprinkled in your gear:

What you eat will vary your VOC signature.  The company Lumen figured that out and uses it to help customers burn fat and avoid diabetes, among other goals, by breathing into a device to analyze the VOCs in their breath.   Hunters, similarly, can recognize that eating certain foods like onion and garlic before hunting will of course show up in their scent signature and possibly frighten away prey.  

Body odor is very important.  Avid hunters have recognized that even sweat generated by walking from their vehicle to the hunting site (usually carrying a lot of equipment) defeats their purpose, so they take a number of measures, extreme to some, to avoid generating offensive VOCs:

• Showering with non-scented products
• Brushing teeth (mint is better than bad human breath and baking soda is even better)
• Using unscented anti-perspirant and sprinkling baking soda in shoes to absorb sweat
• Avoiding pungent foods like garlic, fish and alcohol before the hunt

As we mentioned before, what you wear is huge.  Some of the “hacks” include:

• Washing with unscented or “de-scenting” laundry detergent with no optical brighteners
• Drying clothing outdoors when possible, or without dryer scents when not possible
• Storing hunting clothing in plastic totes away from other stinky areas like garages or kitchens.  Some hunters use garbage bags, but these are typically loaded with VOCs of their own!
• Placing natural materials like fresh pine needles or acorns in sachets in the tote with the clothes to scent them naturally
• Carrying hunting clothing and boots to the site and changing into them, or storing them at the site, to avoid unnatural scents like asphalt and gasoline
• Buying ScentLok clothing (activated carbon lined) to adsorb their scent
• Using de-scenting or “cover” sprays on their clothing periodically.
• Using ozone generators to treat their clothing and equipment to remove VOCs

What we suggest (hunters, let us know what you think!)

• Using TotalClean to de-scent clothing periodically, or on outer wear like coats that aren’t washed after every use.  After all, TotalClean does industrial tasks like de-scenting garbage and waste, in a non-toxic way, using the natural elements of iodine and copper.  You can also use TotalClean to wipe down non-washable equipment like binoculars and guns.  TotalClean can be used in every area of your vehicle to descent it as well, before and after the hunt (dressed meat and dogs for hunting such as squirrels and rabbits can leave quite their own “scent” on a vehicle!)
• Using activated carbon to adsorb VOCs of clothing and equipment while it’s in storage, especially when it's new.  Just cut large pieces from the media and place them below, between and above your clothing in the tote.

Many hunters and scientists advise that you cannot eliminate or block 100% of your VOCs, but using as many precautions as possible can give you precious seconds or yards to make the difference between a fruitful and unfruitful hunt!