Indoor air quality & coronavirus: complete guide

To simplify this important guide, I rolled all the content into one post for reading efficiency. Indoor air quality is an important part of our health, all the more because we are spending more time indoors during shelter in place orders. So why does indoor air quality matter?

  • We inhale 3,000 gallons of air a day, and that air comes in direct contact with our bloodstream, potentially distributing pollutants to all our organs. Think of anesthesia gasses that you inhale that enter your brain in seconds!
  • Indoor air quality may be significantly worse indoors vs outdoors. Certain pollutants are over 1,000x higher indoors!
  • Some pollutants are carcinogenic in our homes, including formaldehyde, benzene, disinfecting products, naphthalene, and perchloroethylene.
  • Children are even more susceptible to air pollutants because of smaller size, increased ventilation, and developing organs.
Dry cleaned clothes on a rack. Dry cleaning can introduce a major source of perchloroethylene, considered a probable carcinogen by the EPA. If dry cleaned clothes give off this odor, be sure to address it at the next dry cleaning visit. This indoor air pollutant can reduce the indoor air quality of your home.
Dry cleaning can introduce perchloroethylene into your home, a probable human carcinogen, and reduce your home indoor air quality.

But there are so many indoor air pollutants, it’s just overwhelming to fix my indoor air quality!

It can be overwhelming, so this guide is a pragmatic approach to build a healthier home environment without the anxiety. The first step is to understand the risk of air pollutants to our health:

Equation summarizing dose-dependence on human health: Risk to our health = toxic load = potency of toxin x exposure time. This helps us understand the impact of indoor air pollutants on indoor air quality.

As examples:

  • A low potency toxin with high exposure can have a high toxic load. Think of an air freshener whose chemicals you inhale every minute.
  • A high potency toxin with low exposure can also have a high toxic load. Think of asbestos in damaged walls.

So how do I reduce these air pollutants to improve my indoor air quality?

There are two ways to remove indoor air pollutants that damage our health:

  1. Remove the pollution source outright, but replacing the item might prove expensive or infeasible.
  2. Minimize the toxic load with small fixes or “hacks” to reduce your exposure from the pollution source.

So let’s start systematically finding the toxic load of each item to reduce our exposure!

Systematic assessment of our indoor air pollutants

 Wood products

  • The threat? Formaldehyde: a resin commonly used in pressed woods and particleboard (also known as chipboard). It can leak into the air through cracks, chips, or peeling. Consider your furniture and cabinets.
  • Toxic load? Potentially high toxic load. Formaldehyde is considered a known carcinogen by some agencies. Exposure can be high if in the ambient air of your kitchen (think cabinets). Gassing typically comes from exposed edges and cracks in wood and can hurt indoor air quality.
  • Solutions:
    • Measure formaldehyde levels with a home test kit, though recognize that the EPA does not suggest a particular test kit and test accuracy can be variable. If levels are high, look for sources in the wood products, like cracks and peeled wood. If you can patch or seal those sources, re-test the formaldehyde levels.
    • Formaldehyde release is increased by heat and humidity. Air conditioning and dehumidifiers can help reduce formaldehyde release.
    • Increase ventilation! Opening windows is a cheap, easy way to reduce formaldehyde build up in your home, particularly when new formaldehyde sources are introduced and gas is released at a higher rate.
Formaldehyde and flame retardants may be present in our furniture and carpeting. These indoor air pollutants can have serious health consequences.
Formaldehyde and flame retardants can be release from furniture and carpeting.


  • The threat? Naphthalene (in mothballs). Pesticides (less likely if organic). Perchloroethylene from dry cleaned clothes. Formaldehyde.
  • Toxic Load: Can be high.
    • Naphthalene, perchloroethylene, and formaldehyde are carcinogens.
    • Pesticides can cause wide-spread problems in the body, though transmission from clothes is not well studied yet.
    • New clothes are most likely to have formaldehyde on them. Same with bedding. Recognize that clothes and bedding have direct skin contact with us, often for prolonged periods of time.
    • “Wrinkle-free” and “non-iron” materials often contain formaldehyde.
  • Solutions: 
    • Wash new clothes to reduce formaldehyde exposure.
    • Wearing organic cotton can lower your exposure to pesticides. Organic bedding and mattress materials can also reduce your exposure.
    • Recognize the ingredients used in non-iron materials.
    • If you use mothballs, strongly consider an agent without naphthalene.
    • Regarding dry cleaning, from the EPA:
      • “If dry-cleaned goods have a strong chemical odor when you pick them up, do not accept them until they have been properly dried.”
      • “If goods with a chemical odor are returned to you on subsequent visits, try a different dry cleaner.”

 Furniture and foam products

  • The threat? Flame retardants.
  • Toxic load? Flame retardants are not benign substances. We have (unfortunate) data from fire fighters who have high exposure to these chemicals.
    • Flame retardants have been implicated in thyroid dysfunction, metabolism disruption, and breast, blood, testicular, and prostate cancers.
    • Flame retardants end up in dust that we inhale or otherwise consume.
    • Check your furniture tags listing the inclusion of flame retardants.
  • Solutions:
    • Check your furniture for flame retardant information tags.
    • Replacing furniture is clearly expensive. Workarounds include wet-mopping and regular vacuuming with a HEPA filter. The goal is to remove the flame retardants from the dust.
    • If you are in the market to purchase new furniture, consider looking for items without flame retardants.
An incense candle burning. The release of fine particulate matter from incense poses a serious health risk from indoor air pollution. Indoor air quality can be significantly affected by burning incense and other candles.
Incense are a potent source of fine particulate matter, which can have serious health consequences.

Combustible items (incense, candles, wood burning stoves, cigarettes, etc.)

  • The threat? Fine and ultrafine particulate matter, based on the combustion source. Carbon monoxide, naphthalene, volatile organic compounds (VOCs).
  • Toxic load?
    • Particulate matter can have hazards greater than secondhand smoke.
    • Naphthalene is a probable carcinogen.
    • VOCs are a broad group of chemicals (including formaldehyde and benzene) that can have mild to severe concerns, including carcinogenesis.
    • Carbon monoxide can be lethal if unchecked. Fortunately, you can control your exposure based on time spend burning.
  • Solutions:
    • If possible, avoid candles, incense, and any other combustible items in the home. Many additives are often added to improve color and smell of candles.
    • While the health impact of every type of additive is unknown, avoiding these exposures in the home is the safest approach.
    • Incense, in particular, are potent air pollutants, and avoiding them is high yield.
    • Carbon monoxide detectors can help minimize lethal buildup of this invisible gas.

Carpets and indoor air quality

  • The threat? VOCs, formaldehyde, flame retardants.
  • Toxic Load? Potentially high toxic load:
    • Formaldehyde is considered a carcinogen (see above).
    • Flame retardants have been implicated in thyroid dysfunction, metabolism disruption, and breast, blood, testicular, and prostate cancers. Unfortunately, we have learned a lot from fire fighters who come in close contact with flame retardants frequently.
    • Most new carpets release the majority of their VOCs within days of use. This is called “off-gassing” and hurts indoor air quality.
    • A problematic scenario is a baby crawling on a new carpet.
  • Solutions:
    • Ensure adequate ventilation for the first few days after a new carpet or rug is purchased.
    • Don’t let children crawl over new carpets! Remember, toxic exposure is higher in children.
    • Formaldehyde can be measured to determine if your carpeting is still off-gassing that particular VOC.
    • Look for labels on your carpet for flame retardant listings. It is difficult to directly measure these chemicals.
    • If looking to purchase a new carpet, consider consulting the Carpet and Rug Institute to find a safer carpet or rug.
A carpet being unfolded. Carpets can offgass for several days. They can release formaldehyde, among other compounds. These indoor air pollutants can significantly hurt the indoor air quality of our homes.
Carpets can release VOCs when new and being unrolled.


  • The threat? Ozone, solvents, toner dust, nanoparticles.
  • Toxic load? 
    • Largely unknown but actively researched.
    • Nanoparticles in particular are actively being studied.
    • Ozone is a known respiratory irritant that can increase susceptibility to infection.
    • Exposure depends on your printer and frequency of use. You can check your manufacturer for emissions levels.
  • Solutions:
    • To improve indoor air quality, open windows to reduce the concentration of these indoor air pollutants.
    • The next time you purchase a printer, check your manufacturer for emissions levels.
A printer. Printers are a source of multiple indoor air pollutants. While we do not know health consequences of all these compounds yet, our indoor air quality is heavily affected by them.
Printers can release multiple indoor air pollutants when active. Consider open windows in the room containing the printer.


  • The threat? Formaldehyde. You need to check the type of flooring you have. Hopefully it isn’t applicable to your home.
  • Toxic Load? Potentially high toxic load, as formaldehyde is an indoor air pollutant and carcinogen as classified by some agencies. Laminate wood flooring can be a source.
  • Solutions:
    • Measure formaldehyde levels with a home test kit, though recognize that the EPA does not suggest a particular test kit and test accuracy can be variable. The EPA has addressed laminate flooring here.
    • There has been media coverage of imported laminate flooring that may have unsafe levels of formaldehyde. Consider checking the manufacturer of your wood flooring.
    • Opening windows can easily help reduce exposure to these indoor air pollutants.

 Electronics and kitchen appliances

  • The threat? Flame retardants (we don’t want the electrical components to start a fire).
  • Toxic load? See above sections on flame retardants.
  • Solutions: this can be challenging. I recommend a similar strategy to reducing the presence of flame retardants from furniture: regular vacuuming (with HEPA filter) and wet-mopping.

Paint and indoor air quality

  • The threat? Lead, VOCs.
  • Toxic load: 
    • Lead is a potent toxin with far-reaching effects across the body. Lead can escape from paint into dust and be inhaled. “Paint chips” can be consumed by children accidentally, leading to toxicity.
    • VOC potency is discussed above. Exposure depends on the type of paint used and time from application (similar to “off-gassing” as carpets, above).
  • Solutions:
    • If your home was built before 1978 you should check your paint for lead.
    • Most modern paint has low levels of VOCs after the off-gassing period. If you are painting your home:
      1. Ensure proper ventilation while painting.
      2. Try to not stay in the room while the paint is drying.
    • VOC off-gassing is highest with fresh paint. Indoor air quality is least affected after the paint has fully dried.

Larger ignitable objects (gas or kerosene stoves, space heaters, leaks from furnaces or from the garage letting in car exhaust)

  • The threat? Carbon monoxide.
  • Toxic load? Can be high and lethal if carbon monoxide is undetected.
  • Solutions:
    • Carbon monoxide detectors can detect lethal gas accumulation early.
    • Always open the garage before turning on your car to prevent gas accumulation. Never idle the car in the garage. Electric cars avoid this problem altogether. Ensure adequate ventilation in whichever room houses furnaces or gas burning appliances. If possible, keep the door closed between the room containing these appliances and the rest of the house.


  • The threat? Many toxins. Describing all of them is beyond the scope of this post. Threats are similar to candles and other combustibles.
  • Toxic load: Very high.
  • Solution: Consider quitting. Be mindful of secondhand smoke, particularly around children. This is a severe indoor air quality concern.
Hobby and craft supplies, including aerosol paint containers. many hobby items include potent solvents that contribute to indoor air pollution. Air quality can be severely compromised by these items if not stored properly.
Aerosol cans release many indoor air pollutants. Proper ventilation is important to reduce exposure.

 Stored volatile solutions or volatile gases: solvents, paints, paint thinners, etc

  • The threat? Many different compounds, VOC’s are a particular concern.
  • Toxic load: Potentially very high, depending on the solvent.
    • Some VOCs in these compounds can be carcinogenic (formaldehyde and benzene).
  • Solutions:
    • Avoid keeping volatile solutions near common household areas.
    • Try to have open ventilation wherever they are stored to minimize gas leaking and hurting indoor air quality. Consider storing them in the garage or other areas that are uncommonly frequented.
    • From the EPA: Buy small volumes of volatile chemicals and throw away partially full containers of old or unneeded chemicals safely.
Various painting and hobby supplies. These items may contain volatile solvents that can compromise air quality. These indoor air pollutants can be potent and should be used and stored appropriately.
Hobby and craft items can be a source of volatile compounds that can hurt indoor air quality.

Hobby items: correction fluids, adhesives, permanent markers, arts/crafts materials, sprays, aerosols

  • The threat? Many compounds, depending on the particular item. VOCs and aerosols are specific concerns.
  • Toxic load:
  • Solutions:
    • From the EPA: Buy small volumes of volatile chemicals and throw away partially full containers of old or unneeded chemicals safely.
    • Try to avoid using aerosolized products unless absolutely needed. Only use them in well-ventilated areas (outdoors, with open windows, etc.).
    • Do not store these items in highly frequented areas. Consider storage in a garage and particularly somewhere to avoid accidental consumption by children.
    • Ensure optimal ventilation (eg open windows) when using these items, such as painting, etc.

Insect repellents: DEET, pet protection (flea or tick collars), etc.

  • The threat? Pesticides and other specific compounds (DEET).
  • Toxic load: Pesticides can have widespread bodily effects.
    • Bringing these repellents into the home increases your exposure, particularly if used in poor ventilation.
  • Solutions: 
    • Don’t bring these repellants in the home on your pets.
    • Try to avoid applying these products indoors.
    • Only apply these products with proper ventilation.
Cleaning supplies. Many cleaning supplies can contain potent toxins. They should be used as instructed, and they should be stored appropriately. Child poisoning is a very real concern. Indoor air quality can be compromised from volatile chemicals and from aerosols.
Cleaning and disinfecting supplies can have numerous toxins, including irritants and carcinogens.

Cleaning and disinfecting products (sprays, wipes, chlorine-based cleaners, etc.)

  • The threat? Chlorine-based products, QUATs, and aerosols (from spray cans).
  • Toxic load? Potentially high, particularly with COVID-19 concerns and frequent sanitizing.
    • Toxicities range from minor irritation/burns to asthma to potentially cancer.
    • This is a large topic, so please see my full review here.
  • Solutions:
    • Some cleaners are less toxic than others, so please read my full review to find the optimal disinfectants.
    • If unable to find a less toxic cleaner, always ensure proper ventilation to reduce exposure.
    • Avoid aerosol sprays whenever possible.

Personal care products (anything with odors or parfume)

  • The threat? Many possible compounds. Phthalates may be released into the air and then inhaled by us.
  • Toxic load: “endocrine disruptors” potentially affecting hormonal systems in the body.
    • May lead to obesity, cancer, reproductive disorders, etc.
    • Can be found in perfume, nail polish, liquid soap, hairspray.
    • Recall that the fragrant chemicals released by these products (often near our faces) have direct contact with our blood stream!
  • Solutions:
    • Be selective with your personal care products. Consult a database that reviews products for toxic chemicals, like EWG.

 Exposed insulation in walls, around pipes, etc.

  • The threat? Asbestos.
  • Toxic load: Severe (mesothelioma).
    • Unfortunately, asbestos exposure does not follow a “dose-dependence”. A single exposure may lead to mesothelioma.
  • Solutions:
    • Follow the EPA’s guide on how to handle asbestos in your home.
    • Asbestos-containing materials that aren’t damaged or disturbed are unlikely to pose a health risk.
    • Only trained and qualified personnel should handle asbestos.
Fragranced products seemingly benign with essential oil. Any product listing fragrance may actually contain phthalates, which can be harmful and reduce the indoor air quality of our homes.
While masquerading as safe essential oils, many fragranced products actually contain phthalates for their smells.

Fragrances (air fresheners, etc.)

  • The threat? Phthalates and VOCs.
  • Toxic load:
    • Phthalates are termed “endocrine disruptors” because they alter hormone action in our bodies. This can lead to obesity, reproductive disorders, cancer, and other disorders.
    • VOCs comprise many compounds, some of which can cause cancer (see above).
    • Exposure can be high. Consider air fresheners outputting a constant amount of phthalates that we continuously inhale. These can significantly affect indoor air quality.
  • Solutions:
    • Avoid products with “fragrances”. Many companies will use a generic ingredient like “proprietary blend”, “parfum”, or “fragrance”. These do not mean the ingredients are benign or safe.
    • Try to go for “unscented” products whenever possible!
    • Avoid air fresheners in the home or car. These output a continuous level of chemicals disturbing our indoor air quality.

Indoor air quality and our environmental health – conclusions

To reach our peak health we need to recognize the integral role of our environments. Armed with this knowledge we can take a big step by optimizing the indoor air quality of our homes, This extensive guide is systematic to help reduce anxiety around the many potential pollutants in our homes. Being knowledgeable about our indoor air quality is an empowering step in improving our health!

Sign up to stay updated with coronavirus updates from Dr. Kaveh

Success! You're on the list.

Patients deserve to know the medical secrets used against them. Please share this information with your loved ones!

If you have more questions, I want to answer them! You can e-mail me here.

The information provided in this post in intended for general education. It is not medical advice. While I make every effort to provide the most up-to-date information, please note that new data is continuously becoming available and may change the conclusions I present here.

1 thought on “Indoor air quality & coronavirus: complete guide”

Leave a Reply