How To Clean Your Indoor Air

How To Clean Your Indoor Air - girl with dog looking out window

Pop Quiz!

Why do sickness rates soar in colder weather?

A. Cold air makes us more susceptible to sickness.

B. Viruses and bacteria migrate to where it’s cold.

C. Viruses and bacteria thrive in cold temperatures.

D. We stay indoors and breathe on each other.

Correct Answer: D

Ah, that took me back to my teaching days and all the joys of test writing. But to the point:

Soaring sickness rates in wintertime have nothing to do with weather temperature, but have everything to do with air cleanliness. When we pack ourselves indoors with little ventilation – such as when school starts or when it gets cold – sickness abounds.

How To Clean Your Indoor Air - chart
This chart shows how flu cases in the U.S. start rising in late September (week 38), which is the beginning of autumn, cooler weather, and the school year. Cases begin to level out in April as temperatures rise and people open window and go outside. It’s no coincidence that the biggest COVID-19 spike in the U.S. was in the winter.

But germs are not all that’s dirtying our indoor air. There are a range of pollutants common indoors. These contribute to the alarming statistic that except for the most heavily polluted urban areas of the world, most of us breathe worse air indoors than outdoors. This is enough of a reality that there are syndromes named after it: Sick Building Syndrome (SBS) and Building Related Illness (BRI). Don’t you wish those terms didn’t need to exist?

Stop and consider: What do you come into the most contact in your home, office, or car? Is it the counters? Floors? Furniture? No. What surrounds you and penetrates deep inside your body, drawn in by the respiration of your lungs? The air. It is flowing into the very core of your body, into your lungs whose primary function is to absorb things out of the air. It’s meant to absorb oxygen, but other contaminants in the air get drawn in, too. So any pollutants in the air are going to end up in you.

Air gets dirty from a variety of sources. If you don’t clean dirty air, dirty air will make you sick.

As a whole we are primarily indoor creatures. One study specified Americans spend 87.6% of their time indoors and an additional 5.5% in a car (which as an enclosed space, can have similar issues to indoor air). So, an average day finds us outdoors only 6.9% of our day, or 1 hour and 40 minutes. Further consider that the most vulnerable populations stay inside the most: the very young, the very old, the ill, and infirmed. These are the people most susceptible and yet most exposed to any indoor air pollutants.

All that to say, it’s important to think about the air. And “indoors” does not mean merely in your house. Your office, car, school, or any other building is also indoors and has air in need of care.

What’s dirtying our air & where is it coming from?

Chemical Contaminants: Volatile organic compounds (VOCs), radon, carbon monoxide, nitrogen dioxide, Perchloroethylene (colloquially called “percs”), formaldehyde, flame retardants, lead, arsenic and DDT (yes, even though it was banned in 1972, it is still regularly found in analyses of household dust).

  • Sources: Outgassing textiles such as furniture, carpets, fabrics, and wood; dry cleaning; cosmetics such as nail polish, hair products, perfumes, or lotions; cleaning products especially disinfectants and anything scented; home maintenance substances such as paint, varnish, pesticides, or air fresheners; printer ink, adhesives, smoke from tobacco or anything burning; soil under your home; dust. Anything you can smell is a chemical that you are inhaling and absorbing.

Biological Contaminants: Bacteria, viruses, mold, dust mites, pet dander.

  • Sources: People, pets, any moisture such as on shower curtains or moist basements, dust.

Particle Contaminants: Dirt, grit, fibers, components of dust.

  • Sources: Dust components include shed bits of human skin, animal fur, decomposing insects, food debris, lint and organic fibers from fabrics, tracked-in soil, soot, second hand smoke, cooking.

I wish I could make the words “volatile organic compounds” flashing and neon to make sure everyone remembers them. VOCs are no joke and represent the biggest source of chemical contaminants in the list. In fact, sources of outdoor air pollution in urban areas are shifting away from vehicle emissions due to effective regulations and towards VOCs coming from indoor consumer products. If they’re detecting outside what we use inside, just imagine how bad their concentration is inside. VOCs come from cleaning products, cosmetics, home maintenance products, inks, adhesives… anything “fumey” has VOCs.

What harm can these do?

Immediate effects of certain chemical contaminants include headache, burning eyes, sore throat, and difficulty breathing. Biological contaminants, especially viruses, bacteria, and mold, can sicken people with a wide variety of acute and long-term illnesses. Particulate matter, especially PM2.5  which indicate particles smaller than 2.5 microns, can penetrate deeply into the lungs and even enter the bloodstream impacting the heart and lungs. Those allergic to particular contaminants could experience sneezing, runny nose, red and itchy eyes, headaches, or fatigue. For those with asthma, all of these symptoms could be intensified and even could trigger an asthma attack. The impact of some pollutants such as radon or formaldehyde may not show up for years, but surface as neurological or behavioral maladies, heart disease, and various cancers. Carbon monoxide poisoning can result in death.

All that to say, this can be serious, but it is not dire because there is much that we can do. Some of these strategies you can implement at this very moment to reduce indoor air pollution.

How can we clean our air?

  1. Control the Source
  • Choose products with minimal fumes especially when it comes to cleaning products and cosmetics. (Yes, that means no bleach. Instead try my All-Purpose Cleaning Spray and other green cleaners.) Look for “low VOC” in paints and varnishes. Ditch artificial fragrances in cleaning products, cosmetics, candles, air fresheners.
  • Leave dry cleaning outside for a day without its plastic on. Let new textiles air outside before bringing them in. And above all, clean the litterbox! (Personal pet peeve!)
  • Ditch the air fresheners and other things we think make our air better. They cause more problems than they solve. From an indoor air quality perspective, air fresheners have been indicated as a primary source of VOCs within buildings.
  • Dehumidify to control moisture. Humidity means moisture and moisture means mold. Not only is mold a danger in itself, but is food for dust mites. Keep the humidity levels in your house under 50%. A weather station or humidity gauge will tell you.
  • Clean house regularly. Get rid of that dust which harbors all manner of contaminants. Vacuum thoroughly using a machine with a HEPA filter. Yes, those hard-to-reach places that nobody sees, too. Don’t forget blinds, curtains, and ceiling fans. Any accumulated dust is breeding ground for dust mites, a powerful allergen.
  • Take care of any moisture-related issue immediately. Signs of moisture include visible mold or fungus, bubbling paint, discolored carpet, stains on ceilings, smell of mildew. You cannot ignore or put off dealing with moisture. It does not get better and will get very much worse the longer you let it go. Some house defects can be lived with for years, such as the hole in my childhood bedroom wall that may or may not have been carved by my brother trying to see how well his pocketknife worked. That was there til my parents spiffied up the place to sell. But one cannot ignore a moisture. I cast my mind back to one mushroom, which I found growing out of my bathroom wall one morning. I went to bed with no sign of misplaced moisture and I woke up to a mushroom. We had a problem. Turns out it was from poor caulking in our tub surround.

2. Ventilate

  • Make the most of your house’s HVAC system, if you have one, by keeping the air returns clear. Do not block them with furniture or curtains and change the air filters regularly. Get a filter with the highest Minimum Efficiency Reporting Value, or MERV, rating your system can take (look it up or ask a professional). MERV ratings of 13 or higher filter out the smallest particles, 2.5 micrometers, which due to their small size can penetrate the deepest into our lungs. Clean the vent slats where dust builds up.
  • Set the HVAC to “Fan” instead of “Auto” to send your air through the filters without running the air conditioning or the heat. However, in high humidity areas, this can cause an increase in humidity in your house (which equals mold), so take a moment to consider whether this is a good strategy for you.
  • Use your stove’s extractor fan when cooking and open windows. Cooking, especially high heat methods such as frying, release an exceptional amount of nanoparticles.
  • Open windows. “Shut the door! I’m not air conditioning the entire neighborhood!” I get it. I’ve said it. We seal up our homes and offices tightly in the name of efficiency. Otherwise, we waste money and energy. However, in not letting heat or cold in, we also don’t let indoor contaminants out. Simply opening the windows, flushing out the air, letting what’s likely cleaner outside air in, is a free and easy step to take.

However, opening windows is not an “all the time and all the way” recommendation. Several factors may make opening the windows not a good idea: high pollen counts, high humidity, high wind kicking up dust, or in my case in October, high smoke. All of these could worsen your indoor air. Check the Air Quality index on your weather app. In areas or on days prone to these conditions, perhaps early in the morning when humidity is low and winds are low, you could open the windows to swap out the air. Here in San Diego, most of the year we can have the windows open at least in the morning or evening, if not all the time.

  • Don’t rely on plants. This was a surprise to me when I read the research last week. I can still picture in my mind the tidy drawing of the respiration cycle in my grade school science book: We breathe in oxygen and breathe out carbon dioxide. Plants breathe in carbon dioxide and breathe out oxygen. It turns out that this is a little unrealistic. The number of plants required to make a significant dent in our respiration would make our houses resemble dense jungles. Also, carbon dioxide is not the only indoor air pollutant, nor the most problematic one.

This does not mean get rid of your plants. If they make you happy, keep them. But do not let them become breeding grounds for molds due to excessive moisture, and don’t think of them as adequate air filters.

3. Purify the Air

The first two strategies of source control and ventilation should be your primary strategies. As a supplement, or when those two methods are not possible, take steps to purify the air.

  • Use an air purifier. Despite the intention communicated in their names, many devices sold as air purifiers do anything but. There is no oversight of the claims made about air purifiers. Those that are ozone generators operate on the idea that ozone can engage and deactivate pollutants. The problem with this premise is that ozone itself is hazardous and causes a variety of respiratory issues. The concentration at which it might decrease other pollutants happens to be the concentration at which it is harmful to human health. Furthermore, several compounds that commonly outgas from textiles react readily with ozone to form an even more problematic airborne pollutant: formaldehyde, a known carcinogen. So definitely ditch the ozone generators.

Any electronic air purifiers that tout UV light, ionizers, electrostatic precipitators, or hydroxyl generators not only also emit small amounts of the hazardous ozone, but have not been proven effective.

The best option for air purifiers are those with High Efficiency Particulate Air (HEPA) filters. Even so, air purifiers are at best a supplement to other the other air cleaning strategies.

  • Let the sun shine in. I learned a new term: Daylighting. Sounds like the opposite of “moonlighting,” doesn’t it? Like daylighting is the job you have in the daylight. It’s not, though. Here, it’s the idea of letting daylight in. One study found that simply raising the shades and letting normal daylight come through glass helped reduce bacterial levels in dust. How easy is that?!

4. Test your air

  • The only way you will know if you have two deadly contaminants in your house is to test. Radon and carbon monoxide are both invisible, odorless, and potentially deadly. Radon is the leading cause of lung cancer among non-smokers, and approximately 50,000 people end up in the ER each year from accidental carbon monoxide poisoning. Both radon tests and carbon monoxide detectors are readily at home improvement stores. A radon test is something you set out for a few days (quick results) or a few months (more accurate results). Then you send in the test for analysis. Carbon monoxide detectors are mounted on your wall and have a siren like a smoke alarm if CO levels get too high. The latter is especially important if you have fuel burning appliances in your house. If either of these pollutants are high, bring in a professional to help you find the best remedies.

Don’t be overwhelmed by all this. First, identify what you’re doing right. Likely you already have some of these under control. Give yourself a gold star for those! Second, identify the ONE step that will have the biggest impact and start with just that one. After you have that under control, pick another.

I started out discussing germs that make us sick. These often get the most attention because such sicknesses surface so quickly, and because we’re emerging from a global pandemic when germs have been on everyone’s mind. While these are a key reason to clean your air, they are not the only reason. Even if you live alone or work alone or drive alone, there are many other types of contaminants whose ill effects may not surface for years.

What are your best ways to keep your inside air clean?

Anytime I research for an article, I am always amazed and grateful for the experts I come across. There are people who have made it their life’s mission to dive deeply into obscure corners of the world and to know them completely, digest that knowledge, and spread it out in ways I can take in as well (at least if I’m paying very close attention). For this article, I learned about the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), the Energy Vanguard blog, and the Green Science Policy Institute. If your curiosity has been piqued by any of what I’ve written, I highly recommend you check out these sources, from which I learned much of what I now know.  

Further reading

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Lynnetta Williams says:

Hello I hear a lot of good things about you and products ..I’m new and want to learn more also try you’re products out ..

Lisa Bronner says:

Welcome, Lynnetta! There are lots of great resources here on my website. I do respond to comments, and I hope you’ll ask if you have any questions.

TJ says:

I use a box fan and put an air conditioner filter in the back. This is a great way to remove contaminants from the air. Keeps the dust down and removes odors. We keep one by the litter box. Also useful when installing new floors or refinishing floors. Much cheaper and healthier than filtration machines.

Anita says:

I finally ditched all our air fresheners in the home. For years, had those automatic spray ones and just didn’t know better. Do you have any tips/suggestions on how to refresh so to speak? We have a couple dogs and I have a sensitive nose lol, and would like to maintain an odor free house yet safe for the family.

Lisa Bronner says:

Hi Anita- I hear you! I too love a sweet-smelling house. A stovetop potpourri is great for this. Throw some fruits and spices into a small pot with enough water to cover. Apples, oranges, lemons, limes, pears – whatever you have on hand. This is perfect for peels, cores, and rinds. Add a small amount of spices – one cinnamon stick or a few cloves or 5 allspice kernels or one star anise. Or a dash of this and that from your ground spices. Maybe a splash of apple or orange juice. Or go super fresh with mint sprigs. Simmer this on the stove or in a small slow cooker. (I like to set a reminder to turn it off in an hour or so.) Try also mixing a few drops of your favorite essential oils into baking soda, which is a great natural deodorizer on its own. Mix with a fork, sprinkle on fabrics and carpets, then vacuum up. (Spot test this first for desired results.) A spritz a bit of our Lavender or Peppermint Hand Sanitizer into the air works for a quick refresh too.

Karima says:

Hi, I love your article about clean air.
Do you have any recommendations of which brand to use as and air cleaner and a humidifier, please and thanx.

Katherine says:

Its nice to have all this information in one place, and easy to read.

Julie says:

Thank you for a very thorough and though provoking article. I learned a lot and was reminded of things I already knew. The one I question though is natural air fresheners – like Essential Oil Diffusers – I have used one for years in both my massage studio and home with Organic Steam Extracted Essential Oils to “clean” and scent the air. Also wondering about burning Soy Organic Essential Oil candles. I do love some candlelight – especially in my Epsom Salt Lavender Bath. Wondering if you have any further thoughts about either of those?

Lisa Bronner says:

Hi Julie- Thank you for your kind words! I too enjoy essential oils and candles. We always light a candle at the dinner table when the stars align and all five of us are able to sit down together. It’s something to celebrate! It is good to know, though, what these can and cannot do. While essential oils have many beneficial properties and uses, they are not effective at cleaning the air. The concentration of essential oil needed to be antimicrobial is not achievable in the air, and they would have no impact on chemical or particular contaminants. They are still lovely for scent and mood and are the healthier alternative to artificial fragrances, so continue to enjoy them in that way, but don’t rely on them to be cleaning in the air. You still need to be employing other strategies. For candles, it sounds like you have the best: organic soy wax with essential oils. Having a cotton or wood wick is also best. Be sure you’re still flushing out the air though because the candles will consume more oxygen and if by chance the wick isn’t trimmed quite right, could emit soot into the air.

Ronnie says:

I installed an exhast fan on a wall not the ceiling in the room near our litter box. I also added a timer where it runs for an hour every 2 hours all day long. The fan is a bathroom exhaust fan. This removes litter box odors and also the dog smell in the house. I’ve had it for about 2 years and it is amazing how much it cleans the the air and removes litter dust. When we open our screened windows we often put a box fan in the window backwards so that it draws the air from inside the house and pushes it outside. Wonderful way to help clean the air.

Laurie says:

I read something about gas cooktops and the particulate matter they emit. In the process of going to induction for better indoor air quality as the main burner of ours went out.

Isharene says:

Thank you so much Lisa this blew my mind all you learn you have to unlearn and refresh not only your home but your mindset🙏🏾❤️

Carolyn M says:

Thanks Lisa. Makes my head spin — so difficult to live healthfully these days! Appreciate these ideas to make improvements. I know some of these will work for us.

Steve says:

Not for everyone but additional mechanical systems such as a heat recovery ventilator in cooler climates and energy recovery ventilators in warmer climates can exchange indoor air by exhausting and replacing stale indoor air for filtered fresh outdoor air while retaining the majority of heat inside with a hrv or outside with an erv.

About Lisa Bronner

My grandfather was Dr. Bronner, my family makes soap, and I share ways to use it plus tips on greener living.

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