Monthly Archives: July 2022

Less Coffee, More Fresh Air!

Less Coffee, More Fresh Air!

At some point in most peoples’ lives, fatigue is a fact of daily life.  We can chalk it up to too much work and not enough sleep, or poor quality sleep, or a virus that seems to be “going around”.  But what if it could be as simple as not enough fresh air?  Simple…yet sometimes not easy to fix, when opening the windows lets in more harmful air than good.  Let’s dig into this “simple” cause…

Different regulations regarding ventilation have been around for a long time, way longer than the American Society for Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) published its first Standard 62 for ventilation. The first, ANSI/ASHRAE Standard 62-1973, Standards for Natural and Mechanical Ventilation, presented minimum and recommended ventilation rates for 266 applications and became the basis for most state codes.(

This standard has been revised several times since 1973, and the current standard calls for homes to “receive 0.35 air changes per hour  but not less than 15 cubic feet of air per minute (cfm) per person.” (  Why?  According to, Clean, dry air consists primarily of nitrogen and oxygen—78 percent and 21 percent respectively, by volume. Without any other contaminants such as carbon monoxide (from combustion) or radon (from the earth) entering a building, humans change the composition because we take in oxygen and breathe out carbon dioxide.  Our lungs can still rebreathe this air “safely” until it decreases below 19.5% (OSHA threshold for oxygen in atmosphere), but increaseing levels of carbon dioxide (CO2) may cause occupants to grow drowsy, get headaches, or function at lower activity levels.  (  What’s the threshold of CO2?  

  • NIOSH (National Institute for Occupational Safety and Health): 1,000 ppm (parts per million in air) are a marker suggesting inadequate ventilation.  

  • ASHRAE recommends that carbon dioxide levels not exceed 700 ppm above outdoor ambient levels.   (Normal range for outdoor levels are typically in the 350-450 ppm range). 

  • OSHA (the Occupational Safety and Health Administration) limits carbon dioxide concentration in the workplace to 5,000 ppm for prolonged periods, and 35,000 ppm for 15 minutes.  

Taking the most conservative route, 1000 ppm is only 0.1%.  Wow, it doesn’t take a lot of CO2 to make stale air!  If this is the gold standard, why are we suffering in stale air?   The answer is that  many places in the US do not require building permits in order to build or renovate a home.  For this reason, it’s up to the homeowner to know what is needed and make sure it’s installed.  If the HVAC technician does not design fresh air into the system, and the homeowner does not know about the need for it, the home won’t have it and the air will be stale.  Case in point: my 1982 home in the country.  It cools, heats, and circulates stale air.  

Take this tweet from Andrej Karpathy and Elon Musk, who know a bit about technology: 

And then the public chimed in: a Stanford professor used to take CO2 measurements in a lecture hall before packing 100+ students in for 1.5 hours, because some halls did not have enough ventilation to sustain deep thought!  Then a restaurant worker began to think, oh, so that’s maybe why I got dizzy sometimes during peak hours of a restaurant?  And another: his son used to wake up crying but since increasing ventilation in his room, the child sleeps a lot more peacefully.  

So if you want to measure your air, lethargy, unclear thinking and headaches don’t have to be part of your day!  There are lots of CO2 monitors on the market, with most starting about $65-70.   This monitor by INKBIRDPLUS shows temperature, humidity and CO2, and also allows you to customize an alarm for different levels of CO2 (they recommend normal (400-700 ppm), warning (700-1500 ppm), and dangerous (1500-5000 ppm)).  

Can you imagine measuring the CO2 while sitting in a conference room or in a lecture hall?  With such technology at your fingertips, there’s no reason to be ashamed to say “I need a break”.   Your brain and body will thank you!

Photo by Call Me Fred on Unsplash

What are Endotoxins and Exotoxins and where do they come from?

What are Endotoxins and Exotoxins and where do they come from?

The word “toxin” causes my ears and eyes to perk up, because these are the types of substances that cause illness and even death.  Thankfully, it is increasingly possible to avoid toxins by understanding where they live and how they’re spread.   Science is advancing very rapidly to show us how to manage our environments, food, lifestyle and even our bodies to live more healthfully.   Endotoxins come from Gram-negative bacteria, and Exotoxins can come from either Gram-positive or -negative bacteria so we’ll start with what the “Gram” test means. 

Bacteria can be classed into two different groups: “Gram-negative” or “Gram-positive”.  These classes are based on a test developed by scientist Christian Gram in 1884, which differentiates the bacteria using a purple stain.   According to, bacteria either have a hard outer shell, or a thick, mesh-like membrane called peptidoglycan.  The hard outer shell will resist the purple stain, and show up as a red color.  These are called “gram negative” because the purple stain did not show.  Bacteria with the peptidoglycan absorb the purple stain much more easily and are called “gram positive”.  The stain also tells more characteristics about the bacteria and the way it interacts with treatment. 

The peptidoglycan layer of Gram-negative bacteria is much thinner than that of gram-positive bacilli; instead Gram-negative have a hard, protective outer shell, making them harder to kill because of their harder cell wall.  When their cell wall is disturbed, or the bacteria are dead or dying, gram-negative bacteria release endotoxins that can make symptoms of illness worse.  In contrast, exotoxins are produced inside the bacteria and may be released while the bacteria cell is living, or during its death.

Here is a diagram that shows how the exo- and endo-toxins are released (source:  (I distinguish them by remembering that endotoxins are only emitted at the “end” of life of the bacteria):

Here are some examples of gram-negative bacteria diseases (

  • Vibrio cholerae (Cholera, a serious intestinal infection)
  • E. coli (E. Coli infection)
  • Yersinia pestis (Plague, an infection of the lymph nodes and lungs)
  •  Bartonella henselae (Cat-scratch disease)
  • H. Pylori (gastritis, peptic ulcer disease, gastric lymphoma, and gastric cancer)
  • Campylobacter (campylobacteriosis, an infection that usually affects the digestive tract)
  • Legionella bacteria (Legionnaire's disease, a lung infection)
  • Salmonella (salmonellosis, a digestive infection caused by contaminated food)

Here are some Gram-positive bacteria (and the infections they cause): 

  • Staphylococcus aureus (MRSA, toxic shock)
  • Streptococcus group A (strep throat, toxic shock)
  • Clostridium botulinum (botulism)
  • Bacillus anthracis (Anthrax) 

As you can see, endotoxins and exotoxins are a serious matter!  Here are some of the other important differences between them (



Are released during death, mechanical damage and lysis of bacteria but also during bacterial growth and division. (

Secreted as part of the cell’s metabolism

Does not have any enzymatic activities

Most activities are enzymatic in nature

Immune response is weaker

Immune response is stronger

Made of lipopolysaccharides

Made of proteins

Moderately toxic

Highly toxic

Cannot be made into toxoids

Can be made into toxoids

Highly resistant to heat

Can be killed by boiling

(A toxoid is a chemically modified toxin from a pathogenic microorganism, which is no longer toxic but is still antigenic and can be used as a vaccine (Oxford languages).)

There is so much to study about bacteria, however since we at HypoAir mainly focus on air quality, we’ll try to limit this post to the toxins that can be transmitted through the air.  

Endotoxins (Endotoxins: Small But Very Significant):

  • Are pyrogens, that is, they often cause a pyrogenic reaction (fever).

  • Cause fatigue, a common characteristic of sick building syndrome. 

  • Don’t produce immunity, but only a temporary resistance known as “Monday fever”. Workers in industries with significant endotoxin levels have been found to be most afflicted on Monday, with reduced effects through the week. Endotoxin resistance is lost over the weekend, with the illness beginning anew the following Monday [5]

  • Are “adjuvant”, meaning that they can amplify the effects of other harmful substances. 

  • Are associated with sepsis, an extreme immune response by the body that often ends in death.  

  • The presence of pets in indoor spaces can represent an important source of air contamination and can be linked with the level of indoor endotoxins. The presence of dogs and cats can be the main predictors of endotoxin levels in house dust [1, 4-7]. Other predictors are the presence of vermin, such as mice, and infrequent cleaning, which indicates poor hygienic conditions in the home [1]. Storage of organic household waste indoors also increases bacterial contamination in the indoor environment [1]. (

Here are some more details about endotoxins.  Although it’s a little in-depth, this article gives a good explanation of what endotoxins are and how they are released (shed) from bacteria.  Basically, endotoxins are small molecules of lipopolysacchride (LPS), which comprise approximately 70% of the outer membranes of gram-negative bacteria. They are responsible for maintaining structural integrity and have been shown to be essential for bacterial survival.  Lipopolysacccharides vary in their structure, but all share three distinct regions:

  • O antigen repeats are found on the outermost domain of the LPS molecule and are responsible for host immunogenicity (the ability of the endotoxin to provoke an immune response in human cells).

  • Core domain is composed of sugars and other non-carbohydrates.

  • Lipid A is the lipid component of LPS, whose hydrophobicity (repels water) facilitates membrane anchoring. Lipid A is responsible for toxicity of the endotoxin.

Here is a diagram of this structure:

Source: What are endotoxins?

Endotoxins are naturally shed at low levels during bacterial growth, but are released in much larger quantities upon cell death when their cell membranes rupture and disintegrate.  A single E. coli cell can release up to 2 million LPS molecules!  As lipids, endotoxins are naturally hydrophobic, which gives them a strong affinity for plastics and hydrocarbon-based materials (vinyl flooring, polyurethanes and coatings on many new products).  

The Limulus Amebocyte Lysate (LAL) test detects endotoxins.  It comprises blood cells (amebocytes) from the Atlantic horseshoe crab (Limulus polyphemus) that clot when they encounter bacterial endotoxin lipopolysaccharides.  The LAL may be used to test in three different ways: to provide a yes/no (qualitative) answer to whether a sample contains a specified amount of endotoxin, or to obtain the quantity of endotoxin via how fast the clotting takes place (turbidimetric) or how intensely the color changes (chromogenic). (Bacterial Endotoxins Testing)  In the qualitative test, equal amounts of a test sample and the gel clot LAL are mixed in a test tube and incubated at 37 °C for 60 minutes.  After the incubation, the tube is inverted.  If sufficient endotoxin is present in the test sample, the solution would have clotted during the hour incubation and a gel will remain in the bottom of the inverted tube (see image below).  If the sample does not contain detectable endotoxin, no clot will form and liquid will run down the side of the inverted tube.  (LAL/TAL Endotoxin Detection Test Methods)  The enzymatic reaction between the endotoxin and lysate produces a yellow color, the intensity of which is directly linked to the quantity of endotoxin present in the sample.   

How can we reduce exposure to endotoxins?

  • Reduce Dust: According to EMLab, a commercial IAQ laboratory in North America, “ Endotoxin exposures are mainly through the air.”  “Endotoxins do not float freely, but instead are attracted to dust particles. Reduction of dust is essential for controlling endotoxin levels. Dust reduction requires both fresh air filtration and filtered air recirculation. Continuous, low flow fresh air ventilation systems without recirculation do not effectively manage indoor particulates. Endotoxin levels and dust levels are not strongly correlated indicating that they come from independent sources. A single dust particle in the 2 to 10 micron range has sufficient surface area to hold a million or more endotoxin molecules (approximately 0.1ng of endotoxin). Therefore, reduction of dust is important regardless of whether one lives in a dusty or relatively dust-free environment.” (this and following points from
  • Removal of food sources: “Coupled with proper ventilation is reduction of source generation of endotoxins. In the home environment, it is clear that kitchens are one source of endotoxin generation. Removal of food wastes and standing dishwater will reduce bacterial growth with subsequent production of endotoxins. Even a bowl of standing water will grow bacteria in a home. Bacteria and nutrients are ubiquitous indoors and outdoors, and they will land in water or moist regions where bacterial growth will occur.” Kitchens have the highest level of endotoxins, followed by living rooms and bedrooms.
  • Avoid use of misting humidifiers: “Cold temperature (misting) humidifiers are strongly linked to high endotoxin levels. Vaporizing humidifiers that heat water to boiling have not been found to produce high levels of endotoxins.” An alternative method for achieving sanitized, cold temperature humidification in a home is through plant transpiration. Plants can reduce toxins in homes [12]. The plant-root matrix releases sanitized water into the air (assuming proper plant care that does not form a wet mass promoting fungal and bacterial growth).

Exotoxins are (from unless otherwise noted)

  • part of a defensive system of bacteria to avoid capture and killing by leucocytes (part of our body’s immune system). (
  • Produced by both Gram-negative and Gram-positive bacteria 
  • More highly poisonous by mass than endotoxins, strychnine, or snake venom 
  • Can be “super-antigenic” or cause stimulation to the immune system 
  • are often encoded by mobile genetic elements, including bacteriophage (phage). Phage can transfer genetic information to the bacteria they infect. (study)
  • Can produce illness even when the microbes that produced them have been killed. (

What are the sources of exotoxins? (from

  • Actinobacteria (especially Streptomycetes), Bacillus species and various other bacteria grow in moist building materials together with fungi. Elements from bacterial structures released in air include bacterial cells, bacterial spores, peptidoglycans, microbial volatile organic compounds, exotoxins, and other bacteria growing metabolites.
  • Gram-positive bacteria with exo- and endospores like Streptomyces and Bacillus can grow on moist building materials. Their spores are very resistant and can survive even if the air humidity is low.
  • Humans are an important source of indoor bacteria. The upmost layer of the normal human skin is continuously renewed, and skin scales containing bacteria are shed into the environment. Bacteria in the respiratory airways are eliminated through Pflügge droplets while talking, coughing, or sneezing. The level of air contamination is dependent on the number of persons inside a room and the efficiency of the ventilation system (natural or artificial ventilation). Bacteria that can be identified in indoor air are micrococci, staphylococci, streptococci, and corynebacteria.

How can we reduce exotoxin exposure?

  • Maintain your home so that there are no active leaks and humidity stays between 40-60%.  This will reduce actinobacteria that produce exotoxins.
  • Practice good hygiene by covering your mouth and nose while coughing or sneezing.  This reduces the amount of small particles in the air that can contain bacteria and exotoxins.  Dispose of tissues in the trash and wash hands with soap and water. 
  • According to the WHO, if exposure to the toxin via aerosol inhalation is suspected, additional exposure to the patient and others must be prevented. The patient's clothing must be removed and stored in plastic bags until it can be washed thoroughly with soap and water. The patient should shower and be decontaminated immediately. 
  • Most exotoxins can be destroyed by heating, (, so eating thoroughly cooked food often eliminates the danger of ingesting the exotoxin. The WHO recommends these five strategies in food safety:
    • keep clean
    • separate raw and cooked
    • cook thoroughly
    • keep food at safe temperatures
    • use safe water and raw materials.

Use of a HEPA filter can reduce aerosols and fine particles containing bacteria, endotoxins and exotoxins, although some of the smaller phages may slip through.  This is where a healthy immune system and abstaining from smoking pick up.  Cigarette smoking is a substantial risk factor for important bacterial and viral infections. For example, smokers incur a 2- to 4-fold increased risk of invasive pneumococcal disease. (2004 study).  In addition, exposure to cigarette smoke causes MRSA bacteria (just one bacteria studied) to become even more resistant to killing by the immune system. (UCSanDiego Health News)  Of course, smoking through a dirty water pipe (bong) is inviting disaster!  Here are the details (

Bacteria, endotoxins and exotoxins are all around us (and even in us), but with good judgment and  precautions, you can avoid being one of the infection statistics!

Photo by CDC on Unsplash

What is Inverter Technology and what does it do for my Air Conditioner?

What is Inverter Technology and what does it do for my Air Conditioner?

To start, let’s review the way conventional air conditioners work.  You set your preferred temperature, and when the room gets too warm, a thermostat sensing the higher temperature will cause the air conditioner to come on.  When the room is cooled properly, the air conditioner shuts off.  The lag in turning on and off varies by unit, but it can be as much as two-three degrees:  at a set point of 72 deg F, the air conditioner doesn’t come on until the room warms up to 73, and doesn’t shut off until the room is cooled to 71 deg F or lower.  In the case of inverters in air conditioners, they can keep the room at an even 72 all day long by running continually with lower power input.  The best way to explain them may be the example of cruise control in a car.  If you try to keep the car at a steady speed, you’ll need to depress the gas pedal when you see the car decelerating, and let up when it goes over your target speed.  Letting the car’s computer keep the speed is actually more gas efficient, because it will sense speed fluctuations sooner, and meter the gas pedal more accurately than you can!  Here is a pictorial by Panasonic:

Once again, the power of computers is making our lives better by modulating the power consumption of the unit and avoiding those annoying temperature swings.   But wait–there’s more!  With only a 2-3 degree temperature swing with a traditional air conditioner, why does it feel like one minute you need an iced drink, and the next you need a sweater?  It just doesn’t seem like that should happen with only 2-3 degrees. The answer lies in the humidity of the air.  Temperature fluctuations cause the relative humidity (RH) to fluctuate, which makes a big difference in comfort levels!   Humidity gets taken out of the air as it passes over the evaporator coils, and this is an important function of the air conditioner, because as you cool the temperature, RH will go up.  If you don’t have a non-inverter air conditioner sized just right (having the optimal compressor power and refrigerant for the size of room), it will run for too long or too short, causing the RH to fluctuate:

  • Too large of a unit means it will run for short cycles, cooling the room quickly but not running long enough to remove adequate moisture from the air.  
  • Too small of a unit means that it will run for long periods of time and humidity will go down, but jump right back up when the unit shuts off.

The inverter air conditioner not only keeps temperature constant, it can also keep humidity lower and constant.  Here’s how that works:

  • Back to physics class:  There are two kinds of heat: sensible and latent heat. Here is an excellent page to understand more, but basically sensible heat is related to changing the temperature of a body (in this case the air), and latent heat is related to the phase change of the body (in this case changing the water vapor in the air to liquid so that it will drain away).  
  • Constant speed on/off systems are good at removing sensible heat to lower the temperature of the air.  However, they don’t do such a great job at removing latent heat (humidity) out of the air.  This diagram shows why: it is a diagram of how much energy is needed to push water into a different phase.  The long flat part at 100 deg C (212 deg F) shows how much energy is needed to change water from liquid to vapor, and once it is a vapor, the same amount of energy (970 BTU, or British Thermal Units) is needed to condense it back to a liquid, without even changing the temperature!
  • So, when the system is set to only lower temperature, it does not continue to supply the needed energy to change the phase of the water vapor in the air to a liquid, to condense it out of the air.  It will simply stop cooling when it hits the temperature set point.
  • Inverter technology uses a computer and variable speed fan to slow down the speed of the air crossing the evaporator coil.  When the air spends more time in the evaporator, more water vapor will condense out of the air, meaning more dehumidification occurs.    It also uses a variable speed compressor to better control the flow of refrigerant through the system, because slowing the fan alone with a standard compressor may cause the coil to freeze.  Since the system will be continually cooling instead of stopping and starting, a variable speed compressor allows for a small steady flow of refrigerant when the room is in a steady state (no one coming in or out or cooking, etc.), but also a ramp-up when someone opens a door or turns on an exhaust fan, etc. 

This is all great information, but what if you have a central AC system that’s only a couple years old, and very little budget to go making changes?  The good news is that it is possible to replace your standard single-speed blower motor with a variable speed motor.  Here are some facts about this type of upgrade:

  • The term “variable-speed” applies to two different components in an air conditioning or heat pump system: the blower motor and the compressor. A variable-speed blower can be matched with a single-speed compressor, but a variable-speed compressor must always be paired with an adjustable-speed blower. (
  • Single speed motors in blower units are generally called “PSC” or Permanent Split Capacitor, while variable speed motors are called Electronically-Commuted Motors (ECMs) or Brushless Permanent Magnet motors (BPMs).  ECM is a trade name for BPM (
  • ECMs come in “3 flavors”: non-variable constant torque, variable constant torque, and variable constant flow.  (David Butler,  If you are looking for better dehumidification, you may want to go for the Variable speed, constant torque model.  The Variable speed, Constant Flow models are the most expensive.
  • ECMs are quieter and use less electricity than PSCs.
  • Retrofitting the blower fan has the following challenges:
    • You’ll need to make sure the existing electrical service is compatible with the new ECM.  Although the resulting operating current draw should be less than the PSC motor it replaced, you’ll need to check that the motor nameplate ratings don’t require upsizing the supply circuit in order to provide the necessary electrical safety.  (Titus HVAC)
    • The new motor may require a different type of mounting, ie. a “belly band” vs. a bracket, and the technician may need to use parts from several conversion kits to install it. 
    • The Building America program retrofitted PSC blower motors with ECM motors at 8 homes in upstate New York in 2013 as part of a study.  The study did extensive screening of homes and systems so that only homes with the right size hp motors, the right size blower housing and cabinets, and the right type of motor mounts were chosen, making the install straightforward for the technicians (US Dept. of Energy).  According to Titus HVAC, ECM retrofit doesn’t just mean replacing the motor. It generally means replacing the motor, the speed control, and blower assembly. It will likely also require additional components like power cables, communication cables, and a power filter. It could even require changing internal options like line and/or motor fuses.  
    • There are several manufacturers for these retrofit motors.  
      • The most well-known may be Regal Rexnord with the Genteq Evergreen motors, also offered on Amazon (this company purchased the ECM trade name).  
      • US Motors’ “HVAC Rescue Motors” series includes bluetooth-enabled motors and some that do not need the aforementioned airflow programming, making for an easier install.
      • The Concept 3 motor used by the Building America Program is currently out of production.
    • A knowledgeable HVAC technician can help you with the decision and options; don’t be afraid to get several opinions!  Ask if he will be taking pressure and power readings before and after the install.  This is key to getting your new motor running right, or preventing an ineffective change to the system.  Here are two links for more information on pressure and power draw readings.
  • Some states or power companies may offer rebates to retrofit your PSC with an ESM, such as this 2013 offer by Minnesota Power. 
  • ECMs will save power on systems that are set to have the fan always “On”, such as when a Whole-Home Polar Ionizer is installed.  This type of purifier runs 24/7 and as such needs the fan to run 24/7.  

If your whole HVAC system is nearing end of life (10 years or more), you may ask about replacing the blower and compressor with variable-speed units, which will give the best energy efficiency available in forced air units today.  Some HVAC companies will try to sell what is easiest for them to install, or what their suppliers recommend, or what has always been done, but there is always room for improvement…keep searching and asking until you find it!

It’s not the heat, it’s the air pollution!

It’s not the heat, it’s the humidity air pollution!

Decades ago, when the meteorologists predicted extreme heat, it seemed they only advised on the necessity to stay out of the sun, drink more water, and cool off more frequently (stay in the pool, yayyyy!).  Now, heat advisories come with more sinister warnings about air pollution levels, and the outdoors are less fun.  How did that happen?  The answer lies in meteorology and chemistry, all cooked up in our atmosphere.

Low-pressure systems are quite famous for moving rapidly across the US and bringing devastating weather like severe thunderstorms, hail and tornadoes.  They can also sweep pollutants like smoke and smog to other states.  High-pressure systems, on the other hand, typically cause stagnant air, which can concentrate pollutants over one area.  (  A “Heat Dome” is an area of high pressure that parks over a region like a lid on a pot, trapping heat. (National Geographic) A Heat Dome caused about 600 deaths in June 2021 in the Pacific NorthWest as a 1-in-1000-year event.  The heat, which broke Portland’s all time record of 107 degrees, was bad enough, but extreme heat combined with stagnant air during a heatwave increases the amount of ozone pollution and particulate pollution. (  Here is where the chemistry comes in.

“Ground-level ozone pollution forms when heat and sunlight trigger a reaction between two other pollutants, nitrogen oxide and volatile organic compounds — which come from cars, industrial facilities, and oil and gas extraction. High temperatures therefore make ozone pollution more likely to form and harder to clean up. Drought and heat also increase the risk of wildfire, which can make air quality worse as smoke drives up levels of fine particulate matter — also known as PM2.5, or soot...Both ozone and PM2.5 carry major health risks. Ozone can cause acute symptoms, including coughing and inflamed airways, and chronic effects, including asthma and increased diabetes risk. PM2.5 exposure can lead to an increased risk of asthma, heart attack, and strokes. Globally, long-term exposure to PM2.5 caused one in five deaths in 2018, including 350,000 deaths in the United States.” (Heat waves can be life-threatening for more reasons than one)

Because of the increase in cars and industry, extreme heat forecasts are not just requirements to have bottled water and popsicles on hand and check that our elderly neighbors’ air conditioning is working.  It’s a time to make sure that those who have asthma, heart and vascular conditions stay indoors, and that you take the proper air pollution precautions, too. 

Unlike outdoor air filled with wildfire smoke, ozone and smog are not as visible and may not affect everyone immediately, but they are dangerous pollutants and shouldn’t be allowed in our homes.  Here are some steps you can take to prepare for that heatwave, and the resulting air pollution that often accompanies it!  

  • Seal doors and windows with weatherstripping, caulk and door sweeps.  

  • Find out how to adjust your HVAC system accordingly: you’ll want to close the fresh air intake and change over to recirculation, no matter whether you have central AC, a window air conditioner or portable air conditioner.

  • Purchase extra MERV 13 filters for your HVAC system, to be used on poor air quality days (caution: read our post on HVAC filters first, as using a filter with too high MERV rating can damage your system). 

  • If you live in an apartment building or condo with little control over the HVAC, consider purchasing vent filter material so you can place them in the vents into your space.  The filter material can prevent smaller particulates in smog from entering.  Carbon vent filter material will neutralize many VOCs as well.

  • Purchase a HEPA air cleaner (non-ozone producing type) and be sure to have an extra filter or two on hand.  The use of a HEPA filter will take much of the damaging fine particles out of the air you breathe!  Whenever there is bad air quality outside, run the cleaner/purifier on high for an hour and thereafter at "quiet"/medium setting (Wirecutter).  You can check out our post on standalone HEPA filters as a purchase guide.  If you can't purchase one, make one: there are many videos and instructionals online for DIY air cleaners; most only require one or more filters, a box fan, and some cardboard and tape.

  • Keep a stash of N95 respirator masks on hand.  These are a good source of protection if you have to go outside, or if power is cut to your home and indoor air quality gets bad as well.  The “95” means it blocks out 95% of particulates.   

  • Keep canned and non-perishable food on hand, so that you don’t have to cook during periods of bad air quality.  Cooking indoors increases small particulates and vapors in the air, and you won’t want to turn on your stove exhaust, as that will draw polluted outdoor air into the house.

  • If air quality is very poor (check next point), you’ll want to evacuate to a place with clean, filtered air, like indoor malls, libraries, community centers, civic centers and local government buildings ( 

  • Check your local air quality and receive updates from . Using an Air Quality Index (AQI) as a measuring tool ranging from 0-500, your local forecast and larger maps can be color coded to show whether an area is good (green), moderate (yellow), unhealthy for sensitive groups (orange), unhealthy (red), very unhealthy (purple), and hazardous (maroon).

Photo by Call Me Fred on Unsplash

Air Filter Thickness–is thicker better?

Air Filter Thickness–is thicker better?

All of the homes I’ve lived in (and there have been many) used 1” thick furnace filters.  Far and away, this is the most popular size.  I hadn’t even realized that there is a significant selection of  4-5” thick filters, until I recently went to a big-box home improvement store and looked at the actual size of some of the filters offered in the air filter aisle.  It was eye-opening.  Who uses these giant filters?  Mega-Mansions?

It turns out, even a modest-size home can use a thick filter.  The thickness of the filter:

  • Determines the frequency of filter changes.  With a 4” filter, you can go longer (3-6 months) between filter changes, vs. 1 month for a 1” filter, making life easier on the one changing the filter.   
  • Usually equates to more surface area (you’ll have to check the packages of 1” vs. thicker filters to verify).  Surface area is the square inches of filter material you are getting in the filter.  With thicker filters, they generally do give more surface area, because the pleats are deeper and more tightly spaced.  More surface area means that the pressure drop across the filter is generally lower (which is better for your system).  
  • DOES NOT refer to capacity to filter smaller particles. (Look at the next point: MERV.)  

I took a look at a popular filter site,  Here’s the comparison:

20x24x1”: (6) MERV-11 filters for $9.98 each (up to 1 month change) = $9.98 per month

20x24x4”: (6) MERV-11 filters for $19.38 each (up to 3 month change) = $6.46 per month

So, if you actually change on schedule, it seems the thicker filters can also be more economical. 

Filtering capacity: As I mentioned above, filter thickness does not affect the particle sizes that are filtered.  It is the MERV rating that does this. (Check out this post for an explanation on MERV ratings).   I selected MERV 11 for the above comparison, but MERV 13 is the optimal rating for home systems, because it filters out many of the finer particulates (from cooking, burning wood and outdoor air pollution) that can damage our lungs and bodies.  For the same size filter, a higher MERV will increase pressure drop across the filter, so make sure that your furnace/air handler will work with the MERV you select. 

I never thought of this before, but I’m sure it’s been tried because a filter manufacturer posted the answer: No, it’s not good to stack (2) 1” filters in a 2” space.  (  The reason is that two 1” filters create much more pressure drop than one 2” filter, and the extra pressure drop is not good for your air handler.  Another expert ( likened this to stacking 4-5 coffee filters in your coffeemaker, adding coffee, and then turning on the machine.  It’s not going to turn out well!

Here is a summary of filter thickness:

If you want to increase time between filter changes, you can look into increasing the filter thickness.  For example, for the same cross-sectional filter area (20x24), a 4” filter can give you 3 months between changes, vs. one month for a 1” filter.  This can be good for those who are maintenance challenged (for example, an elderly person who can’t easily access the filter), or for rentals or seasonal properties where someone is paid to do maintenance.  Increasing the filter thickness may involve hiring an HVAC tech to install a deeper filter box.  Here are some points about changing to a deeper filter box:

  • If your filter is currently located at the return air grille (where the air from your house is sucked into the system for conditioning), then you’ll want to change the location of the new filter to be right next to the air handler.  This is because if you install a thick filter at the return grille, it can cause a pressure drop in the duct, which can cause air leaks from the attic, crawlspace or any other unconditioned space to come into your air duct leading to the furnace. You definitely don’t want dusty, hot attic air coming into your AC system, so it’ s better to locate this filter either underneath the furnace or alongside it ( 
  • If you are considering building a deeper filter box, also consider upgrading in MERV rating, up to MERV 13 (see next point).  The way to get a low pressure drop across such a filter is to make sure the filter box is big enough.  A simple rule of thumb for this is to allow 2.0 square feet of filter area (not counting pleats) for every 400 cfm (cubic feet per minute) of airflow.  For example, 600 cfm will require 3.0 square feet of filter (600*2/400), which can be achieved with an 18x24” filter (3.0 square feet) or a 20x24” filter (3.33 square feet).  According to Allison Bailes of, using this rule of thumb will avoid problems with pressure drop in your system, even with using thicker (4-6") MERV 13 filters.
  • If you are looking to increase filtration, meaning filter smaller particles from the air, you will need to increase the MERV rating on your filters.  Typically MERV 13 is the optimal residential filter, and it’s especially good for those with pets and/or allergies. 

We hope this article has cleared up some questions about these thicker filters, and maybe even induced you to switch over to them.  In this case, thicker is better!

Photo by Brett Jordan on Unsplash

Why isn’t the fan making me cooler?

Why isn’t the fan making me cooler?

This is an odd post.  It’s about hitting an invisible barrier, one you don’t see until suddenly, things don’t work the way they’re supposed to.

When I see an article with the title “Fans Can Make you Hotter”, it’s an automatic click for me.  I rely on fans in every room of my home during most of the year to keep air circulating and help keep the air cooler.  How could fans ever make me hotter?

Well, we’re talking about extreme heat here: in an experiment, it was shown that fans used on volunteers in dry heat of 115 deg F heat index was more uncomfortable and detrimental than fans used on volunteers in humid heat with a heat index of 133 deg F.  In the first scenario, the lack of humidity in the circulating air caused their body temperature, strain on the heart, and thermal discomfort to increase.  In the hot and humid scenario, though, fans actually lowered body temperature and made them more comfortable.  

It’s not hard to understand why: think about a convection oven.  Above a certain temperature (104 deg F), dry air will start to impart its heat back to you, instead of whisking away heat from your skin.  Turning on a fan will only speed up the shift of hot air into the body, making you feel warmer, and potentially raising your body temperature to unhealthy levels.

In most parts of the US, dry heat like this is not a problem, but some areas of the west may certainly find it happening: garages, attics, and enclosed, unconditioned spaces quickly elevate in temperature and if there’s no humidity, be very careful of working there.  A fan in these conditions can hasten heat-related injury.  Here are some tips to stay safe:

  • If necessary to work in these conditions, wet clothing and make a wet headcovering so that the evaporation of water will cool you down.   

  • Take frequent breaks in a cool place (at least every 15 minutes)

  • Drink more water than normal and consume electrolytes

In this case it’s not the humidity, it is the heat!

Photo by Nathan Dumlao on Unsplash

From the Outside In: How to cultivate a healthy yard that will benefit your indoor air!

From the Outside In: How to cultivate a healthy yard that will benefit your indoor air!

Our yards say many things about our home and hopefully, they’re all good!  Because they surround our home, yards also directly impact our indoor air quality.  Here’s how to cultivate healthy air outside, because it will always permeate to the inside.

  • We wrote about the healthy heart benefits of green areas around the home.  To find the right trees and plants for your area, visit i-Tree Species.   Here’s some other tips for landscaping for indoor air quality:

    • Don’t plant shrubs right next to your foundation, so that mulch and soil will get air circulation and mold does not have continual shade and moisture to grow on surfaces.

    • Plants like lavender, basil, thyme, mint, lemongrass, chrysanthemums, petunias, marigolds and mosquito plants provide delicious fragrance and colors that also repel insects! (

    • Try natural pest repellants such as the ones we mention in this post, instead of toxic traditional repellants like malathion and pyrethoids.

  • Get the humidity right: if your yard is low-lying and frequently has standing water, it is very pest-friendly (mosquitoes, fleas and ticks all like water, not to mention mold!).  Consult landscaping companies to find the best solution for raising the elevation and/or draining water.

  • Whole-house generators are a popular addition to homes where there are frequent power outages or the possibility of extended outages (from severe storms or hurricanes, for example).  However, just like portable generators, they emit carbon monoxide (CO), carbon dioxide (CO2) and nitric oxide (NO), which can penetrate homes.  According to electricgeneratorsdirect, standby generators must be located at least 5 feet from windows and doors, and of course in compliance with local codes.   They can even be placed up to 18” next to the house where there are no windows or doors.  In our estimation however, they should be located farther from homes than the regulations require!  

  • It’s important that sewage lines are intact, so that liquids and gases stay where they should!  If they become damaged by cars or large equipment driving over them accidentally, call an inspector to view the lines with a pipe camera and assess repairs.

  • If you have a dusty road nearby, consider planting a row of trees or tall shrubs as a screen.  Bushy, hairy-leafed cotoneaster is a variety that stands tall above others in its ability to absorb particles and pollutants (

  • Find a safe way to store garbage until it’s removed:  nobody wants to smell garbage, so it’s put outside where it can be “safely” stored until pick-up day.  But what about the smell?  You can try:

    • Finding a spot downwind where you can make a small hedge to shield the garbage from view and from direct sun

    • Making sure that the lid can be closed securely (bungee cords are great for this) so that critters do not get in.

    • Using an all-natural additive to remove smell and reduce flies and pests: Teraganix makes a number of microbial supplements for people, gardens, and yes even our garbage!  This one can be sprayed onto the garbage before closing the bag, or even poured down smelly drains.

  • Porches are typically cool, inviting places that say “come and relax”.  If you live near a busy freeway or road, however, pollution can travel farther than you realize, especially in the late night and early morning, traffic pollution drifts much farther than during the day. (  This results from dropping temperature during the nighttime hours when the atmosphere traps car emissions, CO2, and other pollutants down near the ground. (  During this time, it’s not good to be “porch-sitting”, but unless you have particle-filtering air purifiers inside (like a good HEPA filter), inside may not be much better. 

  • The sky is falling, the sky is falling!  If you live in a flight path or downwind of one, it’s probable that PM2.5 levels are substantially higher than in other areas.  Location may be unavoidable, but you can avoid trapping pollution next to  your house by not planting tall trees around the entire perimeter of your property or at least crosswind. Leave spaces for air to blow through and clear the pollutants.  

Interior home renovation may seem to be the most obvious way to increase interior air quality, but don’t overlook the yard outside, because what’s outside, eventually comes inside!

Is there mold hiding in your clothes?

Is there mold hiding in your clothes?

It has been one heck of a summer in the US!  More heat = more sweat, more sweat = more stinky wet clothes in the laundry hamper, and more wet clothes in the laundry hamper = more mold!   This is especially a problem with workout clothing or “outdoor work” clothing that get positively soaked with sweat.  My previous schedule of washing one time per week is not cutting it, because now I’m noticing that even after washing, my clothes are not smelling clean (I don’t use perfumed detergent).  Why can’t I get the mold out with just washing?

Mold is persistent.  Because we’ve been trained to save energy and that modern detergents and washing machines work well with cold water, I’ve basically gone to using cold water for all of my washing.  Cold water and detergent typically don’t remove mold, so after several cycles of letting them sit in my hamper, washing with cold water and drying, the smell intensified.  Something had to change!  This excellent article gives many non-toxic ways of getting rid of mold from clothing:

  1. First of all, the habit of leaving wet clothes in the hamper is not good.  If I can’t wash them right away, I need to hang them up to let the moisture dry out.
  2. If I can’t wash them right away, pretreating with a tea tree oil spray not only helps them smell better, but also kills the mold because tea tree oil is a fungicide!  Oregano Oil or Clove Oil will also work, depending on your fragrance preference.  Be sure to purchase pure oil without additives.  Here is how to make it: 
    1. Add one teaspoon of teatree oil to one cup of hot water; pour it into a spray bottle.  Shake the mixture.
    2. Spray the garment thoroughly, inside and out. 
    3. Let the mixture soak in for 10 minutes before washing.
    4. Pour the rest of the mixture into the washing machine or handwash basin.
  3. If you don’t like the smell of the essential oils (the smell does dissipate within a few hours), you can use hydrogen peroxide in a spray bottle (3% dilution works well) in the same way as the essential oils. 
  4. Borax has been around a long time for good reason– it is a good disinfectant and low toxicity (just don’t ingest it, inhale the dust or get it into your eyes). (  When mixed with hot water, it turns water into hydrogen peroxide. 
    1. Mix ½ cup of Borax with hot water in a large basin, stirring slowly until its fully dissolved.
    2. Soak the clothes in the mixture for at least 20 minutes.
    3. Pour the clothes into the washing machine with the mixture and wash for 2 cycles. 
  5. Vinegar and baking soda:  You’ve probably used this powerful combination before and know that it makes a foamy cleaning agent, except this time use it in separate wash cycles.
    1. 1st cycle: add 1 cup white vinegar to the detergent dispenser, with no other detergent.
    2. 2nd cycle: add ½ cup baking soda to the detergent dispenser and finish washing.
    3. Don’t ever combine vinegar and bleach!  This combination generates toxic fumes.
  6. Closets can be perfect for growing mold, because lack of air circulation can allow moisture to accumulate in the clothes, making them the perfect food source!  We posted an article “Can I avoid mold with JUST ventilation?” and the answer turned out to be oftentimes, you can.  Here are some ways to prevent mold from taking root in the nice clean clothes in your closet:
    1. Leave the closet door open.  If you are keeping your home below 60% humidity, usually this step alone can keep the closet from smelling musty–that first telltale sign of mold.
    2. Try not to pack clothing or boxes tightly together, again because air circulation around items is necessary to keep the humidity down in the clothes. 
    3. If you cannot keep the door open, try adding small dehumidifiers:
      1. DampRid is a brand name that makes a number of desiccant products that you can hang or set on a shelf or on the floor, but there are many comparable products.  Remember that water will need to be poured off, and the chemical absorbing the water will replaced, every so often.  This chemical is usually calcium chloride, which comes prepackaged in the replaceable refills.  Alternatively, you can make your own desiccant dehumidifier by purchasing silica gel or calcium chloride at the hardware store and placing it in small plastic bowls with the tops pierced (just don’t knock them over or the liquid may spill on the floor!)
      2. Small dehumidifiers can make a big difference in closets.  You can get a model to hang on a wall, or place on a shelf (just make sure there is sufficient space above and around it for air circulation).  The condensate container in these will also need to be emptied periodically (although the unit should shut off when full) so put a little reminder on your calendar to do that.  Here are some models that won’t break the bank:
        1. Eva-Dry ($22) makes several “wireless” models, which use silica gel desiccant which must be replaced every 20-30 days. This is a good option for smaller closets (up to 333 cubic feet) without a power outlet, and larger versions are available too.
        2. Eva-Dry also makes electric dehumidifiers; this model ($27) will need to be emptied every 3-4 days but it’s ultra quiet. 
      3. Many customers know that even higher humidity areas like bathrooms and closets can be kept mold free with the Mold Guard/Germ Defender.  It’s a powerful unit that emits a dense blanket of ions that can break apart/deactivate mold spores at the cellular level.  Perfect for spaces of 100 ft2 or under, this unit requires very little maintenance and can be purchased with optional charcoal filters.

The next time you put on clothing from the clean laundry and it doesn’t smell so fresh, it’s probably not you (or your deodorant), it may be mold.  Arm yourself with some natural anti-fungals like vinegar, baking soda, teatree oil, hydrogen peroxide or borax, and banish the mold from your wardrobe!

Surround yourself with trees, and your heart will thank you for it!

Surround yourself with trees, and your heart will thank you for it!

We tend to surround ourselves with what brings us comfort.  It might be your favorite music, your favorite color, your favorite art, and even your favorite pillow or type of sheets when you go to bed.  What if your source of comfort actually made you healthy?  Where you live and what you do with your property is an important choice that can affect your heart health.

We’ve been told for some time that plants have psychological and physical benefits–just look at this page of studies!  A new study (2021) correlates the proximity of living near trees, to arterial stiffness.  According to a 2010 textbook, “Arterial stiffness describes the rigidity of the arterial wall. In the last decade, there has been increasing interest in the potential role of arterial stiffening in the development of cardiovascular disease in adults.”  In addition, the 2015 book Early Vascular Aging states, “Arterial stiffness is a hallmark of arterial aging. As with all other organ systems, changes in the vascular system are induced over time.”  This is very important, because cardiovascular disease (CVD) is the leading cause of death worldwide.  Although many associate CVD with genetics, “recent estimates suggest that up to 70%–80% of CVD burden could be attributed to non-genetic environmental factors, such as lifestyle choices, socioeconomic status, air pollution, lack of surrounding greenness (2), and residential characteristics (2018 study). Indeed, emerging evidence has shown that living in greener areas results in improved health and is associated with lower mortality (2016 study on mortality of women, 2016 study on green spaces and mortality), and reduced CVD risk (2019 study, 2012 study).”

How does the “proximity to greenness” cause these positive effects?  Is it because vegetation promotes exercise or a healthier lifestyle?  Or because it reduces stress?  Trees do have the ability to filter and block particulate matter, and it has been shown that people living in greener areas were exposed to lower levels of volatile organic compounds (2020 study).The 2021 study focused on reduction of pollution, particularly ozone and PM, due to plants and trees in specific radii around the home, and the effect of the reduced pollution on the participants’ arterial data.

What is proximity to greenness?  The study used satellite-derived normalized difference vegetation index (NDVI) for a 200-m and 1-km radius around each participant’s home; the 200 m range was directly around the home, while the 1 km radius indicated walking distance.  Data on ambient levels of pollutant concentrations were retrieved from regional EPA-validated monitoring stations in the Louisville, KY region, that report daily pollutant levels.  The data included PM2.5, PM10 and ozone. 

Here are some specific results: 

  • At smaller radii (200 m) buffer around the home, inverse associations between standard deviation of NDVI and augmentation pressure, aortic pulse pressure, and aortic systolic pressure were observed (as greenness goes up, arterial stiffness goes down). 
  • Significant positive associations between several arterial stiffness metrics and pollutants in low greenness areas were observed, whereas the association between pollutants and arterial stiffness measures was not significant in areas of high greenness (as greenness goes down, arterial stiffness goes up).
  • Arterial stiffness was only associated with NDVI at the 200-m radius, but not the 1-km radius, giving support to the theory that because roadways are sources of pollutants, street trees within a 200-m radius around the individuals’ residence would be more relevant in blocking exposure to pollution. 
  • It was shown that ozone, but not PM2.5, was significantly associated with higher augmentation index (increased arterial stiffness). This suggests that ozone-induced effects on arterial stiffness are independent of PM2.5 exposure and potentially stronger.
  • In addition to modifying the effects of air pollution, proximity to greenness may improve cardiovascular health by decreasing mental stress. Exposure to natural outdoor environments has been found to be associated with better mental health and could facilitate stress reduction (2017 study), and neighborhood greenness is associated with lower levels of self-perceived stress and depression (2018 study), particularly in older adults. In our work, we have found that higher levels of residential greenness are inversely associated with urinary levels of the stress hormone—epinephrine (2018 study). Hence, it seems plausible that some of the effects of greenness on arterial stiffness may be mediated by a reduction in mental stress. 

How can we apply these findings to our own lives?  Since “greenness” is good for our bodies, plant as many trees and shrubs as possible, and encourage your neighbors to do so as well, by letting them know how good it is for them and the neighborhood.  The 200 meter radius is equivalent to 656 feet, which when converted to square feet (656 x 656) is equivalent to 2.3 acres.  That is a big green space that not many people own for their own property, but when spread out over a neighborhood or nearby park, it is certainly achievable.  If you live near a busy highway or road, definitely plant as much green area on the border of your property as you can. 

Some tree species are better than others at absorbing pollution, because as we’ve mentioned in other posts, some plants take in ground-level ozone, while other plants emit isoprene, a VOC that reacts with other atmospheric chemicals to create ozone. (Scientific American).  You definitely want the former type!   Here are some tips:

  • A free online tool called i-Tree Species helps you to select the best plants depending on desired hardiness (after all, if the plant won’t live in your area it won’t do much good to introduce it), mature height and environmental factors such as air pollution removal and air temperature reduction, among other factors.
  • In one recent study, Barbara Maher and colleagues at the University of Lancaster tested the ability of nine tree species to capture PM in wind-tunnel experiments. Silver birch, yew and elder trees were the most effective at capturing particles, and it was the hairs of their leaves that contributed to reduction rates of 79%, 71% and 70% respectively. (
  • Conifers, such as pines and cypresses, are the best pollution filters, while London plane, silver maple and honey locust ranked above average too, according to Jun Yang, an urban ecologist at the Center for Earth System Science, Tsinghua University in Beijing. (
  • If you have the opportunity to give input for city-wide greenery initiatives, be aware that taller species of trees can trap pollutants in areas, so sometimes shrubs are better when narrow streets are surrounded by tall buildings. 
  • If you do have a large property or even a city park to design, remember to diversify the species so that certain pests or adverse conditions like too much or too little rain will not wipe out the whole property.  

In all, green spaces mean gold stars for your heart health, so it’s time to start seeing green!

Photo by Pankaj Shah on Unsplash

Did you know that there is a science called “Building Biology”?

Did you know that there is a science called “Building Biology”?

In my quest one day to find individuals who are qualified to give advice on healthy homes, I ran across this term: Building Biology.  Building Biology is a building philosophy and science that originated in Germany in the early 1960’s, as “Bau-Biologie”.(  World War II forced a massive rebuilding effort in Europe and many buildings proved to be unhealthy for their residents.  Europeans realized, before North Americans, that residents’ health is very dependent on the health of their homes, so they incorporated 25 principles of nurturing environments into this field of study.  Indeed, one can see that if they followed all 25 principles, there would be no reason for ill health due to the home or its location!  It’s a holistic approach to building. 

Holistic is “characterized by comprehension of the parts of something as intimately interconnected and explicable only by reference to the whole.” (Oxford Languages)  In theory, it is a very sound practice to look at the “whole” rather than just the parts!   However in the US, “holistic” often has a bad connotation.  For instance, the term “holistic medicine” is often heard in national media sources to sarcastically or derisively describe all manner of “folk remedy" health care choices that don't usually involve actual MDs. (  In a country of doctors who are mainly paid by insurance companies with clear financial incentives, holistic doctors tend to be in the minority.  For the same financial reasons, holistic homebuilding is in the minority as homeowners seek to build the best-looking (but not necessarily healthiest) home for their budget, and rising material costs may force builders to cut corners in material quality. (  In defense of the “science” of Building Biology, there are specific test methods and evaluation guidelines used by Building Biologists.  “Building biology is science because it creates knowledge, practical to apply, practical to use knowledge, because building biology pursues research, finds facts, informs, and uncovers the truth. Building Biology Testing Methods are objective, transparent, reproducible, science-based. Knowledge forms the basis for change, improvement. Frequently, building biology ideas and pioneering projects have paved the way for necessary and long overdue scientific research. Frequently, building biology creativity and courage to bring up painful subjects have led to more sensible and compatible industrial products that protect humans and the environment. All activities within the framework of Building Biology Testing Methods are based on human needs and the nature, not the industry, not politics, not exposure limits or regulations, not the public health office, not research that got lost in too much theory and tangled in dubious ties. We building biology professionals are independent and do not care about science when science loses sight of humans and nature, when incalculable risks are generously accepted, when it turns into a wish foundation for an insatiable industry. Building biology is an essential addition to science, blazing a trail for research. Building biology blows life, especially with practical relevance, into orthodox science.” (Questions about the Standard of Building Biology Testing Methods and the Building Biology Evaluation Guidelines)

There are many of the 25 principles that relate to Healthy Indoor Air, a main focus for us at HypoAir.  We’ve written on these extensively without referring to Building Biology, but we’re definitely in agreement that a holistic approach is the best one when it comes to your health.  It all depends on your priorities.  If you have an overarching goal to make your home as healthy as possible, using materials and methods that mimic the good parts of the outdoors, then we’ve found it will positively affect your health!  Compromises need to be carefully weighed before a major investment, because sometimes it’s very difficult to regain health when a poor decision is made.  Many leaders in the fields of holistic medicine and mold sickness, just to name a few, have past stories of poor health due to living situations that forced them to make radical changes and research to resolve and heal.

How different are these principles from the typical “green buildings” of today?

Many green building principles would align with Building Biology principles.  Take these three Building Biology principles: 

  • Strive for a well-balanced ratio between thermal insulation and heat retention as well as indoor surface and air temperatures

  • Use humidity-buffering materials

  • Keep the moisture content of new construction as low as possible

However, the methods of achieving them are very different.  Traditional green building would use non-toxic modern materials to include vapor and air barriers to prevent moisture ingress.   Building Biology prefers breathable walls via Mass Wall Construction for the building envelope.  “Alternative natural materials such as earth and straw or certain types of manufactured blocks have the ability to buffer large amounts of moisture. These historically derived methods of construction differ from standard cavity wall construction techniques in that manufactured vapor barriers are not installed to retard the flow of vapor through the walls. Instead vapor is allowed to naturally flow through the massive walls. Because temperature change in the flow-through process occurs very slowly and because these hygroscopic materials such as wood and clay have the ability to adsorb and desorb large amounts of moisture without deteriorating, accumulation from condensation is insignificant. When a home is properly constructed using these mass wall techniques it will be an extremely comfortable environment with a high degree of temperature and humidity stability. Furthermore, because the solid walls themselves provide insulation and can be finished with a covering of plaster or furred-out wood applied directly to them, the need for synthetic exterior sheathing, batt insulation, gypsum board, joint fillers, and paint is eliminated. Many volatile organic compound (VOC) contamination sources are thereby eliminated as well.” (Permeable Walls and Moisture Control Factsheet)

In addition, Building Biology principles include areas in which the typical homeowner does not invest a lot of thought, but are very important to our health, like the water system.  This may be because many homes are now built with community water systems, or bottled drinking water is readily accessible, but these “systems” do not guarantee protection from Microbial, Inorganic (includes lead, asbestos), Organic (other than microbial), and Pesticides and Herbicides contaminants.  Building Biology addresses each of these contaminants with best healthy practices to eliminate them. (Water Purity Factsheet)

But what does it cost to adopt these principles into our dwellings in terms of money and time?

Like any other field, there are certified experts for hire to help you navigate healthy home choices, whether you are planning to build a home, remodel, or just find a new rental.  If you don’t have the budget to hire an expert, you can educate yourself via free videos, free fact sheets, and free downloads (  

For a consultation, here are a few Building Biologist certified experts:

Because homes constructed on Building Biology principles have sustainability and health goals, some methods of construction are uncommon and some take longer than the usual quick-frame timber/vinyl siding style.  For example, EcoNest Homes in Oregon emphasizes building “Living Sanctuaries of Clay, Straw and Timber”.  However, having dabbled in the construction/remodeling industry myself, there is a very true saying: You can have two out of three, but not three out of three, of the following:

  • Good

  • Fast

  • Cheap

Good and Fast will not be Cheap.  Fast and Cheap will not be Good.   Good and Cheap will not be Fast.  However, if you want to abide by Building Biology, just keep “Good” as one of the non-negotiables by abiding by as many of their principles as possible, and you can achieve a healthy home!   This is one of my concerns: that everyone should have access to healthy housing, not just the rich.  In agreement with this concern, states that building biology “aspires to become the foundation of everyday building activities, not just a luxury for a few”, and “includes all relevant costs up front, not passing them on to future generations and the environment.”  

These are principles to live by!  

Photo by chi m on Unsplash