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So you’re in the market for a new car? With or without New Car Smell?

So you’re in the market for a new car?  With or without New Car Smell?

If the idea of driving a new car is appealing, you may need to educate your nose to accept that the new car smell is not a good thing.  Thankfully, many automakers are becoming conscious of the dangers of volatile organic compounds (VOCs) that compose most new car smells, and are taking steps to reduce them.  Not a small driver for this is the new car market of China.  Over 11% of buyers in China complained about the odors they found in their new cars, according to the 2019 JD Power China Initial Quality Study. (The Self-Poisoning Car)  Apparently, Chinese prefer for their new cars to have no smell at all, which makes sense due to their genetics.  Many Asians possess a less functional acetaldehyde dehydrogenase enzyme, which is responsible for breaking this VOC down, therefore they may be especially susceptible to its allergenic effects. 

When you know about what is in the “new car smell”, you might not be too disappointed when it fades away!  Most of the smells are due to VOCs, some toxic ones at worst.   The sources are varied:

  • Residual compounds from the manufacturing process and material treatment of different interior components and textiles.   These include flame retardants (FRs), of which tris(1-chloro-isopropyl) phosphate (TCIPP) had a 99% detection frequency in a 2024 study.  TCIPP was the dominant FR detected in the vehicle seat foam, and air concentrations of this chemical increased with increasing temperature.     
  • Adhesives and carrier solvents that will de-gas – as much as 2kg of adhesive can be found in a modern car, much higher than in the past where mechanical riveting and bolting was more common]
  • Degradation of cabin materials over the longer term as a result of oxidation, ultra-violet light and heat. 

There are no worldwide standards for interior VOCs on new cars, but Asian countries seem to have some of the most well-defined guidelines.  Here are some of them:

Source: The Self-Poisoning Car

Testing VOCs with professional equipment can yield surprising results.  Even in a 1-year old gasoline Hyundai i10 (an economy car produced in India but not sold in the US because it was deemed too lightweight), methanol and acetone rose dramatically as the car stood in the sun for 5 hours, only reaching 68 degrees F.  After the five hour test without the engine on, the car was started, windows rolled up and AC on max with recirculation mode.  This yielded another surprise: some VOCs such as acetaldehyde rose steeply during the fourth to sixth minutes. During this phase acetaldehyde concentrations rose from an initial base of approximately 50 to 550 μg/m3, more than ten times the regulated limit in China and Japan. It was suspected that the air conditioner acted as a “sink” for some VOCs, which was flushing them out during this time.  (The Self-Poisoning Car)

VOCs in cars have even led to a new condition: Sick Car Syndrome (SCS), a phenomenon in which drivers and passengers experience short-term health problems owing to the accumulation of volatile organic compounds (VOCs) in vehicle cabins [1], [2] and is particularly prominent in new rarely used cars. The symptoms of SCS include irritation of the eyes, nose, and throat, headaches, and dizziness, among other symptoms, with potential long-term health consequences.  (Elevated volatile organic compound emissions from coated thermoplastic polyester elastomer in automotive interior parts: Importance of plastic swelling)

Some solutions from automotive material suppliers include: 

  • UK company Aqdot has introduced the product Aqfresh, which is a powder composed of barrel-shaped molecules with a hollow hydrophobic cavity and polar portals, enabling them to tightly bind a wide spectrum of unwanted molecules.  Aqfresh can be applied to textiles via dry impregnation, as well as by spraying and padding during the finishing process.  It can also be incorporated via compounding or polymer masterbatch into rigid plastic parts such as dashboards and other trim pieces.  
  • 3M has developed low VOC adhesive tapes and a water-based spray-on adhesive (no VOCs) that meet the Japanese Automobile Manufacturers Association (JAMA) standards for nine substances with defined limits for vehicle indoor air quality (VIAQ).  
  • POM is an acronym for the chemical name polyoxymethylene. It is generally referred to as polyacetal or acetal resin.  POM has a number of applications in cars where it replaces metal such as door locks, fuel system parts, door rollers, and clips to hold trim in place.  It has properties of durability, oil and chemical resistance, and self-lubrication.  However, traditionally POM was a source of formaldehyde.  Polyplastics has developed a number of grades of POM that are low-VOC in its DURACON® POM LV Series

Although there are some brands that historically have higher customer ratings for interior air quality (like Honda), the last comprehensive survey of new car VOCs was in 2012, and recent reports by individual automakers regarding interior VOCs are very hard to find.  You can definitely call individual manufacturers and inquire about VOCs while shopping, but when it comes down to deciding,it’s best to see/test cars in person:  What you see in a “floor model” may not be what you get in your delivered car, either, since a 2007 study showed that interior VOC emissions varied greatly between makes, models and trims and even within the same make/model/trim.

You can do a lot to rid your car’s interior of most of its VOCs. Here are some tips to do it (How to Get Rid of That New Car Smell (Step by Step))

  • Heat, ventilation, and time are certainly the main ways to offgas a vehicle. You can heat it by putting it in the sun, by running the heating system, or even with space heaters (very carefully in a small space).  When you are heating materials you are releasing the VOCs and also creating new VOCs (this study explains), so make sure when you are heating up the new vehicle you are airing it out substantially at the same time so that the gasses have somewhere to go.  Windows should be open while you are heating the vehicle. Windows can also be left open anytime it’s safe to do so.
  • Deep clean the vehicle with non-toxic products:
    • You can use AFM Carpet Shampoo to deep clean carpets and upholstery; just make sure not to soak these surfaces in order to extract all the water and prevent mold growth.
    • Vacuum frequently with a HEPA vacuum.
    • Wipe down hard surfaces with disposable cleaning cloths so that you can throw them away after picking up dust, which is what many chemicals from the plastic bind to.  TotalClean is a non-toxic cleaner that’s safe for cleaning soft or hard surfaces in the car (again beware of soaking soft surfaces, however, because of the danger of mold and water rings when the material dries.)
    • Use an adsorbent like activated charcoal.  You can cut and place this filter media wherever you want in the car, and even use large pieces of it to cover seats when you’re not using them.  
    • Use an Air Angel all the time; the AHPCO cell is especially good at removing VOCs, and you can use it from your car’s power plugs while driving, or plug it into a wall receptacle via extension cord in your garage.
    • Unfortunately, flame retardants used in the foam parts may continue to off-gas for the life of the parts, so use fresh-air ventilation whenever you are driving and the outside air pollution permits you do so.

If VOCs are not reduced through the heat, ventilation and time method, you can block them using sealants. This really is the last resort, because sealing prevents further offgassing.  AFM makes a number of non-toxic products for this purpose and questions about their best application can be answered by The Green Design Center.

  • Fabric seats and carpet: AFM Lock-Out is sprayed on.
  • Vinyl: AFM Hard Seal is applied in thin coats using a sponge
  • Other Plastic Surfaces: AFM Acrilaq is best applied with a pad applicator in 3 light coats, sanding lightly between coats. .

 

If you’re used to the good old-fashioned “smells” of just fresh air and sunshine, ditching the new car smell should not be hard for you…hopefully it’s the same for whoever else will be driving your new car.  A final option would be to look for a lightly used car from someone with non-toxic habits–just like the price, the VOCs should also be reduced considerably, and even if it was “professionally cleaned” by a dealership, those cleaning chemicals can be removed using the same steps above.  Goodbye, little air freshener trees, hello fresh air!

Photo by Sarah Brown on Unsplash

How do emergency shelters get fresh air?

How do emergency shelters get fresh air?

If you must go into an emergency shelter, then you can bet that conditions outside are not good, whether it’s a natural disaster, war or safety from criminal activity. You can store many supplies such as food and water for staying in a shelter, but without clean air, survival will only be minutes instead of days, weeks or months!  There are a number of things that air and ventilation systems need to accomplish for shelters:

  1. Providing a positive pressure at all times so that contaminated air from leaks or outside sources does not enter the shelter.

  2. Filtering out contaminants such as nuclear, biological, chemical (NBC) or smoke toxins. 

  3. When the shelter must be completely closed up due to bad air quality outside, two things must happen: 

    1. Removing carbon dioxide (CO2) byproducts of the people residing in the shelter.

    2. Providing supplemental oxygen to replace the oxygen depleted by residents

Let’s go through these in order.  When the shelter is not being used or only tested during good external conditions, then its ventilation system can operate like your home system: bring in outside air, send it through filter(s) to remove dust and normal microbes like mold and bacteria, and keep a slight “overpressure” of 0.3 inches of water so that leaks in the shelter’s walls and doors will only cause air to move out, never in.  The exhaust “vents” are really one-way valves that only let air go out, so that air coming in is controlled.  They also protect residents of the shelter from any explosive “blast” of pressure and debris.  For this reason, they are called overpressure blast valves.   

The flow of fresh air should be similar to what is required at home: according to US standards, that is 0.35 air changes per hour (ACH) or 5 cubic feet per minute per person, whichever is greater (5 cfm is the specified minimum required by the US military, whereas 15 cfm is the recommended supply for ventilation in residential and commercial buildings).  That said, 5 cfm is usually the design criteria to remove the moisture and carbon dioxide (CO2) that shelter residents exhale, and make them feel comfortable.  The air intake must be protected from water and animal intrusion and sufficiently distant from the exhaust (overpressure blast valve) so that used air is not recycled through the shelter.  Routing airflow through the shelter ensures that the exhaust is in the airlock (the chamber where residents enter and exit) so that any outdoor contamination is flushed out with the positive air pressure.

NBC filtration (or as the military defines it CBRN: Chemical, Biological, Radiological, and Nuclear) requires unique filter material.  Pre-filters are used to keep dust and particulates out of the airstream, and then activated carbon impregnated with specific minerals is used to adsorb gasses that may be emitted during disasters or wars.  For example, the activated carbon may be mixed or “doped” with potassium permanganate, potassium iodide, or magnesium dioxide or copper dioxide (see our article on what these materials remove from air). These are not typical systems used in home ventilation, as the activated carbon must be in sufficient purity and quantity to allow filtration for a number of days until outside air clears.

In the event that outside air is heavily contaminated, the ventilation system will need to be completely sealed off and the shelter will operate more like a submarine, where supplemental oxygen is added and CO2 is removed.  The atmosphere needs to be maintained close to ambient outdoor air, at 19.5% oxygen and less than 0.2% (2000 ppb) CO2, and that’s a complex task when humans are using oxygen and expelling CO2 every minute!  It’s good in this case to use the same two principals we introduced in our article on submarines: use good instruments to measure the air quality and have redundant systems to ensure that each function is maintained in case of system failure.  In well-planned shelters, it’s common to have the following instruments: thermometer, humidity meter, differential pressure gauge (to maintain 0.3” water overpressure), smoke alarm, low oxygen detector, carbon monoxide alarm, carbon dioxide alarm, and a radon meter. (NBC Air Filtration Systems)

Although NBC filtration systems can be expensive, systems for adding oxygen and removing CO2 are even more expensive and complex.  Here are some ways that military and professional systems do it (Air Supply Principles in Isolated Shelters & Chambers):

Supplemental Oxygen is available in three different methods:  

  1. Oxygen can be stored in a gas form under pressure or as liquid oxygen in cylinders, and released from these tanks when needed.

  2. Oxygen generators can separate oxygen from compressed air stored in the tanks, or even generate oxygen from electrolysis of water (passing an electric current through it).

  3. Oxygen “candles”, also called chlorate candles, are a very hot-burning cylindrical candle that actually puts out oxygen instead of consuming it.  

Removal of CO2 requires even more chemistry. On average, each person produces 1 kg of CO2 per day, and buildup of CO2 in the air is lethal (see our article on CO2 levels).  Therefore one or more of the following systems is needed:

  1. CO2 scrubbers use a soda lime or lithium hydroxide material to remove CO2 from the airstream, but they produce a lot of moisture and heat and require space for storage of filters and material, which could be prohibitive for smaller bunkers.

  2. Regenerative carbon-dioxide removal systems use a solid amine material and are advantageous in terms of space required, but have a high energy consumption and are costly to install.  

Since air supply is one of, if not the most, critical aspects of a shelter, these systems are best designed and installed by professionals who have experience.  In the survival shelter industry, NBC filter systems made by Israeli and European (Finnish and Swiss) companies differ significantly from those made in the US and UK.  The former systems are more robust, with significantly better materials, engineering and more generous carbon supply than others.  (NBC Air Filtration Systems)

Due to threats of war, disease and scarcity, many people are becoming interested in emergency shelters, but an improperly designed or constructed shelter can be more life-threatening than life-saving!  If you are interested in building or buying an emergency shelter, we recommend you check out this article and research first.  Having a place to retreat in emergency requires a lot of forethought and planning to truly make it "safe"!

Photo by Billy Freeman on Unsplash

Tight homes need ventilation, but what do I do when it’s smokey outside?

Tight homes need ventilation, but what do I do when it’s smokey outside?

If you’re blessed to be living in a “tight” home (one that doesn’t allow much unintentional air leakage), you should know that mechanical ventilation is really helpful, if not necessary, to achieve healthy indoor air.  Humidity, CO2, particulates and VOCs can build up inside your tight home and without intentional ventilation, can lead to major mold and health problems quickly.  In this case, many people opt for an ERV or HRV so that the energy savings on their tight home don’t go “out the window” (literally!) by exhausting indoor air and pulling in outdoor air without some kind of energy exchange.   For more basic information on building tightness, ERVs and HRVs, check out our article here.

If you have an HRV or ERV and live in an area prone to wildfires, you should prepare for them by having the proper filters in place and knowing what to do with your system.  We’ve helped several clients prepare for this scenario recently, and the “smoke” was not all from wildfires!  Sometimes neighbors with bad or even innocent habits like smoking, barbequing, or sittin’-round-the-campfire can all wreak havoc on your air quality.

First of all, be familiar with your HRV/ERV unit!  This means knowing where it is, how to change its filters, and how to operate the different modes.  Hopefully the installer did a good job of allowing room for maintenance, because just like a furnace/air handler, the filters must be changed or cleaned regularly in order for the unit to work well for many years.  

Many units only come with standard MERV 8 filters, but these are not adequate to handle smoke.  Smoke presents 2 problems: particulate matter (PM10 and PM2.5) and volatile organic compounds (VOCs).  According to the US EPA, a HRV or ERV unit filter must have a Minimum Efficiency Reporting Value (MERV) of 13 to provide effective protection against particulate matter in the air we're going to breathe inside a home or office building if it's smokey outside. (How to keep wildfire smoke out of homes with mechanical ventilation systems?)  Therefore, you’ll need to know what grade filters are in your unit now, and if they are below MERV 13, inquire with the manufacturer on which filters to upgrade to. 

Before you buy new filters, however, you should consider the other part of smoke: VOCs.  You can have a MERV 16 in your unit, but it will not capture VOCs and your home will be filled with the smell of smoke if there is smoke outside!  These insidious gasses are most easily removed with activated carbon.  Therefore, a layered filter (with MERV13 or more plus activated carbon) is really the best defense against smoke.  Since not all units/manufacturers offer carbon in their filters, here are some other options to get rid of the particulates AND VOCs: 

  • Check our offerings to see if we have your filter size in a MERV 13 filter plus carbon.
  • If not, you can cut and layer activated carbon media behind/under your manufacturer’s MERV 13 filter.
  • ((Some units use “panel” filters which are basically squares of bulk filter cut to fit the unit.  In this case you can cut your own using laminated MERV 13 and carbon media. ))

The following options are adapted from HRV with Smoke Filtration:

  • Ensure there is positive pressure inside the house during wildfire events (some ERVs like Panasonic ERV can be balanced to deliver more air than is exhausted from home) so that smoke never wants to come in “illegally”.  
  • Add an inline fan/filter to the intake of the ERV.  This would generate additional positive pressure without overloading the ERV fan and also filter the air before it hits the ERV.  This one has a MERV 13.
  • Get a local HVAC shop to fabricate a filter box that uses a regular furnace filter with MERV 13 (or higher) and carbon, sized sufficiently to overcome any static pressure concerns, and install it in the fresh air intake before the HRV, OR you can add a media filter cabinet to the fresh air intake of your HRV/ERV and leave out the HRV/ERV filter on that side.  We can help with calculations on sizing the cabinet if you have the model of HRV/ERV available (basically it comes down to airflow/CFM). 
  • Lastly, you could add one or more air purifiers or Corsi-Rosenthal cubes (CR cubes) with HEPA/carbon) to your home.  However, this is not ideal because the pollutants have already entered your home and you’re relying on these purifiers to clean your air, instead of having a “guard” filter at the entrance.

Now, here’s the part which requires discernment: in which mode to use the HRV/ERV.  

According to this article on how to keep wildfire smoke out of your home, the intake dampers of HVAC systems should be closed during wildfire incidents, and the equipment should be configured to only recirculate indoor air.  Before any smoke event occurs, you should check that the intake dampers have seals on them and they actually close tightly.  In case you think that you would run out of oxygen in a very short time in this scenario, that just isn’t the case.  Consider this calculation for 1 person staying in a completely sealed space of approximately 600 ft2; they would possibly die of carbon dioxide poisoning (at 12 days!) before low oxygen would be an issue.  Here’s where having carbon in your filters is also good, because it can also filter out some CO2 from inside your home while you close the outside vent and recirculate.  We think that a CO2 meter is a great thing to keep on hand whether or not your home is tightly sealed, and especially if you have any combustion appliances (like gas stoves, water heaters, furnaces, dryers, etc.)  

(I wouldn’t even worry about this “12 days” deadline, either, because very-tightly sealed homes are very rare!  A home in Alaska currently holds the record for being the world’s tightest home, and the owner/builder took the ingenious route of building a “box within a box” in order to air-seal and insulate it well enough for the climate.  At 600 ft2, it has a rating of 0.05 air changes per hour at 50 pascals of pressure (ACH50).  This is less than 10% of the very rigorous Passivhaus standard, which is 0.60 ACH50.)  

So, recirculating air instead of bringing in outside smokey air has a few benefits:

  • It saves your filters and uses them only to filter the small amount of smoke that leaks in through unauthorized leaks (or briefly opening a door). 
  • It maintains the air quality of the room above that which you would have if you were bringing in outside smokey air.
  • Depending on where the intake filter is located, it could save you cleaning your HRV by not passing unfiltered smokey air through it.

This last point may not be obvious, but not all HRV/ERV manufacturers consider that wildfire smoke is a real threat to the operation of their units, because some have intake filters on the exhaust side of the heat exchanger:

Source: “How ERVs Work”

Do you see the “Fresh air from outside” on the lower left?  Imagine that this is “smoky air from outside”, passing through the fan and then through the heat exchanger, before passing through the filter on the upper right.  All those particulates just passed through a heat exchanger, and it’s likely that some of them get stuck there until they are manually cleaned out. Particles sticking to a heat exchanger reduce its efficiency and depending on their chemical makeup, may damage the surface of the heat exchanger.  Now, placing the filter on the lower left poses a maintenance issue, but it shouldn’t negatively affect the operation of the fan or heat exchanger.  This is why having a separate filter on the fresh air intake before the HRV/ERV and leaving off that top right filter inside the unit, may be the best option in wildfire areas. 

One last point: although we’re not huge fans of completely “smart” homes due to the EMF they emit, if you travel a lot or have an HRV/ERV system installed in a vacation home, it is worth practicing operating it remotely (via an app).  In real emergencies, roads can be closed quickly and if you are not able to get home right away, it becomes the difference between being able to come “home” to a clean house and one that smell like smoke (because even carbon filters will not be able to adsorb VOCs for an extended or intense event).  

Any smoke (cigarette, wildfire, campfire, barbeque, industrial or traffic accidents, etc.) is very unhealthy, so we need to do our best to keep it out of our homes, even at the cost of not ventilating for the duration of the smoke event.  The particulate matter in smoke is especially dangerous for children and people with respiratory or cardiac conditions, because fine particulates can pass from the lungs to the bloodstream. The best line of defense against particulate matter is an airtight building envelope, which by extension means closing the intake dampers of ventilation systems.  Filters with a MERV 13 rating or higher, and activated carbon if possible, should be used in HRV or ERV systems and central air conditioning units so that these units can remove any smoke that gets in.  One or more portable air cleaners with a HEPA filter and carbon are also a very good addition for use in common rooms or bedrooms at night.  It all comes down to preparation…having the filters on hand (or better yet, already installed) and knowing how your unit works is worth a lot of clean air when the smoke suddenly appears around your home! 

Photo by Egor Vikhrev on Unsplash

Knock out the NOx

Knock out the NOx

This title may sound like an ad for high-octane gasoline, but I’m talking about air pollution here!  In air purification “PM” or particulate matter often steals the show and drives the decisions behind purchasing this filter versus that filter and this purifier over that one.  But what about the gasses in air pollution?  Gasses are not particulates–they are harmful molecules in the air that cannot be filtered out by plain HEPA filters.  So what are they and how can we get rid of them?

NOx is one term for two nitrogen gasses commonly found in urban areas.  It includes nitric oxide (NO), which is a colorless, odorless gas, and nitrogen dioxide (NO2), which is a reddish-brown gas with a pungent odor.  They are produced during combustion: in factories, in transportation vehicles, and even boilers for heating apartments, office buildings, hospitals, universities, etc.  They’re also produced indoors by gas stoves and furnaces when they are not properly vented. 

Nitric oxide in ambient conditions is not harmful, as it dilates (relaxes) blood vessels and improves oxygenation.  However in higher concentrations, it does two things: it will create a burning sensation in your throat and chest as it changes into nitric and nitrous acid, and it goes deep into your lungs to react with blood cells and eventually be excreted by the kidneys.   Nitric oxide in the air that is not breathed in is converted to NO2, the other dangerous nitrogen gas, or precipitated in moisture as acid rain.  (Poison Facts: Low Chemicals: Nitric Oxide)  

According to Clarity.io, a manufacturer of air monitoring sensors, nitrogen dioxide pollution stays mostly concentrated in the area where it is emitted, meaning that areas with high vehicle traffic like urban areas tend to have the highest NO2 levels. (Clean air cities: Innovative approaches to improving air quality in urban settings)  NO2 is a pretty nasty gas: it causes inflammation of the respiratory pathways, worsened cough and wheezing, reduced lung function, increased asthma attacks and is likely to be a cause of asthma in children. (Nitrogen Dioxide)  

If you’ve been reading our articles or have any experience with air pollution or wildfire smoke, you’ll know that outside pollution eventually makes it into our homes, because they’re leaky.  Thus, we don’t have a “safe place” to get away from air pollution unless we leave the city or take steps to make our home air cleaner.  As we already discussed, just buying a plain HEPA filter or making a DIY air filter (Corsi-Rosenthal box) will not take NOx out of your home.  There are ways to get rid of NOx, however: upgrade to a HEPA filter with activated carbon, AND eliminate the sources of NOx inside your home.

A 2014 study conducted in Baltimore, MD found that a two-pronged approach really helped reduce the NO2 in homes:  

  1. Replacement of unvented gas stoves with electric stoves reduced NO2 concentrations by 51% and 42% in the kitchen and bedroom, respectively, indicating that stove replacement impacts NO2 concentrations beyond the kitchen (even when the home also has a gas furnace or drier).

  2. Placement of air purifiers with HEPA and carbon filters in the home results in a nearly 27% decrease in median kitchen NO2 concentrations immediately (1 week after placement), and reductions were maintained at 3 months following intervention. 

Although the study also included the addition of a ventilation hood in some homes, it was unclear whether the hood helped lower NO2 emissions (ventilation does help remove air pollution, but it depends on strict use of the hood during and after cooking).  

Activated carbon adsorbs the NO2 and secures it in the filter, until the filter is changed.  Adsorption of NO2 can be enhanced by 38-55% by adding coatings to the activated carbon, such as potassium hydroxide (KOH).  (Development of an activated carbon filter to remove NO2 and HONO in indoor air)  Even wildfire smoke has NO2 in it; according to this Canadian government environmental webpage, wildfire smoke is a complex mixture of gases, particles and water vapour that contains pollutants such as: sulphur dioxide, nitrogen dioxide, carbon monoxide, volatile organic compounds, fine particulate matter (PM2.5), and ozone.  Activated carbon can handle these gasses and VOCs, while HEPA filtration is used against PM2.5

Therefore, city dwellers, take note!  Whether it’s “business as usual” as pollution from downtown traffic penetrates your home, or wildfires hundreds of miles away turn the skies orange and hazy, a purifier with HEPA and activated carbon is your best bet to knock out the NOx.  Be on the lookout for purifier giveaways, too!   Here are some programs being offered at this time:

  • San Joaquin Valley Air Pollution Control District (California) is giving away air purifiers to keep residents safe from air pollution.  If you live in the area, you can apply for one here

  • The City of Philadelphia is giving air purifiers to early-childhood education centers and schools.  You can learn more and link to an interest form in this article.

  • Project N95, a national non-profit working to protect people and their communities during the COVID-19 pandemic and beyond, has begun a donation pilot program of air purifiers for schools and other organizations.  You can fill out their form here.

Keep your eyes and browser open, as other organizations may spontaneously donate during events like the Canadian wildfires (the University of Connecticut gave away 100 DIY purifiers on June 8, 2023).  During such a time, it’s the neighborly thing to do!

Photo by Jacek Dylag on Unsplash

To-Do List: Change the Cabin Air Filter in your car and ADD CARBON!

To-Do List: Change the Cabin Air Filter in your car and ADD CARBON!

I know, car maintenance is not everyone’s “thing” and air filters sound super-boring.  However, if you’ve owned your car for a while and never changed the filter, or bought a used car and have no clue when this filter was last changed, you could be horrified at what you would find (and hence are breathing in every time you drive it)!  It’s time to think of this task as a “health upgrade” for you, the driver or passenger!

Cabin air filters in cars (tip: these are different from the engine air filter) are probably even more neglected than household air conditioning or furnace filters, for several reasons:  our car ventilation systems are exposed to even more dust, toxins and critter debris than our homes, and many people are averse or afraid of car maintenance.   However, it’s so easy to order the right filter online with your car’s model and year, and now virtually every maintenance procedure on every model car can now be found on YouTube.  There’s no excuse for rolling up your sleeves and getting to it (or bribing your teenager or neighbor to do it with some food)!   Simple tools like screwdrivers, sockets and a vacuum cleaner are usually the only things needed. 

Before you order the filter, however, check to see if they are available with activated carbon.  If so, definitely get that one.  Not only does carbon help with smells in your vent system and car interior, it can remove NO2 from ventilation air.  Nitrogen Dioxide (NO2) is a by-product of fuel combustion and it irritates our respiratory system, causing flare-ups of asthma, which can trigger a visit to the emergency room if the coughing and difficulty of breathing is not controlled.  Over time, NO2 can actually cause asthma or respiratory infections.  A study in the UK at the University of Birmingham showed how much the activated carbon lowered NO2 levels compared to basic pollen filters.  In heavy traffic, many people close the windows and put the ventilation system on “recirculation mode”, which helps reduce NO2 levels by about 1.6 times compared to open windows.  However, you shouldn’t keep the windows closed and recirc on for extended periods of time because CO2 levels will start to rise; maintaining appropriate ventilation is also important to prevent drowsiness.  Here’s the alternative:  using external ventilation with activated carbon filters fitted.  Even with fresh air coming through the ventilation system, NO2 levels were 6.6 times lower than levels with windows open.  Also, in-vehicle NO2 levels were on average 14.3 times lower with closed windows and recirculated air.  It just makes sense to go with activated carbon if it’s available in a filter for your car. 

With minimal research and $, you can feel a lot better about the air you breathe on every drive.  Then, you can place a reminder on your calendar to do it again next year, and keep up the good habits!

Photo by Ivan Bogdanov on Unsplash

What’s in a chemical filter?

What’s in a chemical filter?

Current events certainly stimulate a lot of research, and the accidental release of toxic chemicals from storage and transportation units is no exception.  When a dangerous chemical is odorless and colorless, how can we possibly protect ourselves and the air in our homes?  Enter chemical filters, which are actually already available for purchase.

Many gas filtration media start with a base material and then add (impregnate) the base material with specialized materials.  Since all of these base materials have a multitude of miniature holes that can get “plugged up” with dust, it’s best to make sure the dust filter is clean and in place to preserve the life of the chemical filter.  The base material is incredibly light because of the vast amount of internal surface area it has in its many cavities and holes.  The way these materials  purify air is called “adsorption” (in contrast to absorption).  Adsorption and absorption both “suck up” liquids or contaminants, but there is a difference:  a sponge will absorb water, but eventually the water leaks out or evaporates.  Activated carbon, activated alumina and zeolites adsorb certain chemicals, some including water, but the adsorbed liquid or gas does not escape because a chemical bond is made, until the material is regenerated with high heat.  Since adsorption is a surface phenomenon, good adsorbents are those having large surface areas per unit mass and high attractive forces for the compounds to be adsorbed, called the solute. Although all molecules are adsorbed to a certain extent, those having high polarity are likely to be more strongly adsorbed than those having low polarity. Since water is a highly polar material, it is much more strongly adsorbed than hydrocarbons, for instance. (Air and Gas Drying with Activated Alumina)

Here are the most common base materials:

A main ingredient in these filters is activated carbon.  We’ve written about it here but when you have something more dangerous than sweaty socks or cat litter smells, we like to dig a bit deeper on its capabilities and limitations.  Activated carbon removes volatile organic compounds (VOCs) and acid gasses, which make them useful against a wide variety of pollutants.  To review, VOCs are compounds that have a high vapor pressure and low water solubility.  They are natural and human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. (EPA.gov)  An acid gas is any gaseous compound which, when dissolved in water, will form an acidic solution.  Many industrial compounds are acid gasses, but did you know that we actually exhale an acid gas?  Carbon dioxide (CO2) is an acid gas, and activated carbon is a method for removing excess CO2 in a space.  

Base Material

Activated Carbon: around $1150 per ton (coconut shell)

What it adsorbs

VOCs, acid gasses

Pros

Cons

Lightweight and large surface area

Adsorption is lowered in humid environments

Fairly inexpensive

Filters exposed to the air eventually “fill up” with CO2 and water

Filters available in many sizes and price points

Not many consumer-grade activated carbon filters are “recycled”; regeneration of the media may or may not be possible depending on the chemicals adsorbed

Activated alumina is another base.  It’s a porous, solid form of aluminum oxide, otherwise known as Al2O3 or alumina. This is the same mineral that makes up the precious gems ruby and sapphire, with impurities being the source of the stones’ bright colors. After activated alumina has been evacuated of existing moisture by heating it, the high surface area and many pores of the material allow for the uptake of water and other molecules through adsorption.  (What is Activated Alumina?) At about 1.5 to 3 times the cost of activated carbon, activated alumina is pricier but very attractive for adsorbing different chemicals.

Base Material

Activated Alumina: around $1800-3600 per ton

What it adsorbs

Water, acidic gasses including CO2, and others

Pros

Cons

Lightweight and large surface area

Smaller range of adsorbed chemicals

High crush strength

Since it has a high affinity for water, moisture can reduce the capacity for adsorbing chemicals

Can also act as a catalyst for some chemical processes

Not many consumer air purifiers use this material 

Zeolites are another base material for chemical adsorbents.  They can be naturally occurring or man-made.  Zeolite has an aluminosilicate framework. Which simply means minerals composed of aluminum, silicon, and oxygen, plus countercations. This framework provides exceptional strength and stability to the honeycomb structure. It also makes it very difficult for the positively charged atoms (cations) to leach from Zeolite. (What is Zeolite?)   Molecular sieves are a type of zeolite that are manufactured to precise frameworks and pore sizes for specific applications.

Base Material

Zeolite: $1600-2200 per ton

What it adsorbs

Water, manufactured zeolite may adsorb VOCs if alumina is removed, molecular sieves can be even more chemical-specific

Pros

Cons

Lightweight and large surface area

Manufactured zeolites can be expensive

Less sensitive to water than activated carbon

Not many consumer air purifiers use this material but Austin Air is one

Higher crush strength than activated carbon

Well suited to low concentrations of VOCs

Molecular sieves can be tailored to the molecules they adsorb

Now that you know some of the base materials, additives (also called “doping”) can enhance capture/filtration of specific contaminants.  

  • Potassium Permanganate is added when sulfurous compounds may be present (such as hydrogen sulfide and sulfur dioxide).   According to this filter company, their molecular sieve impregnated with potassium permanganate oxidizes gaseous pollutants such as hydrogen sulfide, sulfur dioxide, formaldehyde, ethylene, mercaptans, and various aldehydes and alcohols.   Do you know what mercaptans are?  They are the sulfurous, rotten-egg smelling additives that are added to natural gas to help you know that there is a leak.

  • Potassium Iodide:  some AustinAir filters are impregnated with potassium iodide, for increased removal of formaldehyde and ammonia.  They are best used in places like new homes, laboratories, beauty salons, funeral homes, etc. Sources of formaldehyde in homes can be carpets, wood panel, construction materials and furniture upholstery, if not an outright chemical leak. (achooallergy.com)

  • Magnesium Dioxide and Copper Oxide: The air filter company Blueair adds these compounds in their activated carbon filters to remove carbon monoxide, ethylene oxide, and ozone.

So which filter is best for me?  It’s hard to plan for every scenario, but you may take into consideration the following:

  • This article/table by the California Air Resource Board (CARB) in response to the Aliso Canyon gas leak (California, 2015) describes what types of filters are in a number of high-end air purifiers.  The models may have changed slightly but it can give you an idea of how air purifiers can be used to reduce specific chemicals (mercaptans were judged to be the source of most peoples’ health issues).

  • If you live very close to a refinery or manufacturer of specific chemical products, you may want to find out what chemicals they manufacture, store and load, what VOCs/fumes are produced and what air filter is best to remove those VOCs. 

  • If you are interested in a particular type of filter, look for (or ask for) test data that verifies it removes what it’s designed to remove.  In an MIT study of 4 consumer-grade air cleaners, only 2 of them removed the VOCs toluene and limonene effectively.  

  • In the case of radon, activated carbon filters (and the others mentioned above) will not adsorb radon gas, but they will adsorb most of the radon decay products (termed “radon daughters or progeny”), which are actually the source of health issues associated with radon. (Reduction of Radon Working Level by a Room Air Cleaner).   Therefore, activated carbon is not recommended for first-line defense against radon infiltration into your home; a venting system is more appropriate and you should contact a professional if you have radon in your home.

  • In the end, activated carbon is widely used for a reason: it removes a lot of VOCs!  If you don’t have a specific chemical that you’re concerned about, this type of filter is a readily available, broad spectrum weapon against many pollutants.  If your air is particularly dusty, you’ll want to make sure that it also has a HEPA pre-filter to protect the activated carbon from getting clogged with dust.

Photo by Paul Teysen on Unsplash

Scent Control for Hunters

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!