Home air pollution: (how to improve indoor air quality)

We like to think of our home as a safe haven, a place to get away from the problems of the world. One of those problems is air pollution, and, unfortunately, indoor air is often more polluted than outdoor air. That’s true even in industrialized areas with bad air. We all need to think about how to improve indoor air quality.

What’s more, many people spend as much as 90% of their time indoors. And so even if outdoor air were cleaner than indoor air, we would have more exposure to air pollutants indoors. 

And modern sealed houses minimize exchange of air with the outside. Pollutants that originate indoors stay indoors. Improving home air quality is critical. 

Indoor air pollution affects our health. Immediate effects resemble such common illnesses as colds. They include eye, nose, or throat irritation, headaches, coughing, sneezing, fatigue, or even dizziness. It can be difficult to know if these symptoms come from some bug or from indoor air pollution. 

Long-term effects of repeated exposure to indoor air pollution can include various chronic respiratory diseases, heart disease, or cancer. Fortunately, we have a lot of ways to improve indoor air quality.

What is indoor air pollution?

Indoor air pollution comes from contaminants in the air, and especially contaminants introduced to the air indoors. In other words, letting outdoor air indoors admits whatever pollutants exist outside. Indoor air pollutants start indoors and tend to stay there.

Common indoor air pollutants include

• combustion byproducts
• household products
• biological air pollutants
• radon

Combustion

Combustion means burning. Burning releases nitrogen oxides and particulate matter into the air. In addition, incomplete combustion releases carbon monoxide.

Gas stoves, dryers, and furnaces have been in the news lately as some jurisdictions seek to ban installation of new gas appliances. Compared to other pollutants, they seem not to be a major problem. Burning food, even on an electric stove, is a kind of combustion, by the way.

Lots of people enjoy fireplaces or candles. Does some government have to try to ban them, too, to protect us from enjoying ourselves? 

Most candles, by the way, are made from petroleum derivatives. They release the same toxins into the air as burning diesel fuel. If you enjoy candles, don’t light too many at once and blow them out after no more than an hour. Switching to soy or beeswax candles can minimize problems.

Smoking, whether tobacco or marijuana, pollutes the air more than any other combustible material. Health hazards of second-hand smoke are well documented. If you must smoke, do it outside.

Household products

We use a number of products in our homes that affect indoor air quality. These include cleaning products, paint and other finishes, and supplies for our hobbies. We also buy new furniture, new carpets, and have clothes dry-cleaned. Many of these products contain toxic chemicals that contribute to indoor air pollution. Besides cleaning chemicals, some furniture is made with wood treated with formaldehyde and/or assembled with toxic glues.

Volatile organic compounds (VOCs) make an especially important class of chemicals that affect indoor air quality. They evaporate from solids or liquids at room temperature. Not all VOCs are toxic and not all products with toxic chemicals contain VOCs, but many products contain VOCs that are not necessary for their effectiveness. Or, for that matter, are necessary for an unnecessary effect.

Check the labels of your supplies. If you see “fragrance,” it means a VOC (or a combination of many VOCs) that manufacturers have added to smell good. The only function of air fresheners is to release VOCs into the room.

Some VOCs do not smell good. Other smelly products, including bleach and ammonia, are not technically VOCs. Besides fragrances, other products likely to introduce indoor air pollutants include anything in an aerosol can, anything with bleach or ammonia, oven cleaners, rug and upholstery cleaners, and polishes for floors and furniture.

If something smells bad, it’s unhealthy. Find an alternative. If something smells good, it may be unhealthy, anyway. One of the best ways to improve indoor air quality is to avoid buying products with VOCs. 

If you like to use products that smell good, look for products that use essential oils. They are VOCs but unlikely cause the same problems as manufactured VOCs.  

Biological air pollutants

Biological sources of indoor air pollution include germs, viruses, mold, mildew, pollen, pet dander, and dust mites. Anything solid can become dust if it breaks down into small enough pieces. You can see it settle on surfaces, but air currents can lift it back into the air. 

And so if your home is infested by mice, other rodents, or roaches, their feces and dried urine can become airborne as dust. Microscopic dust mites emit body wastes and eventually die. Other sources of dust include hair and dead skin (from humans, pets, or vermin), fragments of clothing, and whatever you track in from outside on the soles of your shoes. 

Radon

Probably all indoor air contains some radon, a radioactive gas naturally present in soil. If your home has a basement, or if any part of your home is below ground, you likely have a higher concentration of radon than homes without either. Well water can also have high radon concentrations. 

Since radon is colorless and odorless, the only way you can know if you have a problem is to monitor it. You can buy either a radon detection kit or hire a professional inspector.

Unfortunately, if you have a radon problem, you need to get special equipment to improve home air quality. Contrary to the claims of some companies, ordinary air purifiers do not remove radon.

Easy ways to improve indoor air quality

If you smell something foul and it turns out your dog has pooped on the rug, you would naturally remove the poop. You would not simply try to cover up the odor. The same principle applies more generally. Get rid of whatever causes home air pollution.

As in the case of dog poop, you may have to keep some things that pollute the air out of your home. You can also use ventilation to replace stale air with fresh air or filtration to clean the air and remove contaminants. These methods work effectively together to improve indoor air quality. 

Source control

The best way to improve home quality is to eliminate the causes of pollution. That can be easier said than done. 

You can choose low-VOC cleaning supplies and paints easily enough. You can also easily stop using candles, air fresheners, and aerosol cans. It is, of course, notoriously difficult to stop smoking.  

Pet lovers won’t want to give up their pets, either. Some breeds don’t shed as much as others. You can prefer one of those. Good grooming and bathing habits likewise reduce pet dander.

To stop bringing outdoor pollutants indoors, keep a rug or mat close to the door to wipe stuff off the soles of your shoes. Better still, leave your shoes by the door.

Unfortunately, reducing indoor pollen when it’s in season means leaving the windows shut just at the time the outside temperatures are so delightful. 

Source control does not mean source elimination. Your cleaning routines can keep them under control, provided your cleaning products don’t add VOCs and other pollutants to the air.

Vacuum your rugs and carpets regularly, using a vacuum cleaner that has a HEPA filter. Clean the filter regularly. Prefer hard floors and area rugs to wall-to-wall carpets. You can launder small rugs from time to time. Dusting or mopping the floor removes more dust than vacuuming the carpet.

When you dust furniture, use a moist cloth or microfiber cloth. Otherwise, you’ll only be moving dust from the surface to the air. 

Finally, try to keep indoor humidity between 30-50%. Higher humidity encourages mold and mildew, which become a biological air pollutant. Clean up mold and mildew wherever you find it as soon as you find it. But beware of bleach, which is itself a potent air pollutant.

Ventilation

Since indoor air is likely to be more polluted than outside air, a good way to improve indoor air quality is to let more outside air in. Some outside air leaks in through various joints and cracks.

More significantly, outside air comes in when you open a door or window. Outside air improves the air quality indoors only if it’s cleaner than inside air. You shouldn’t leave windows open when pollen counts are high, during ozone alerts, or when fires are burning nearby. And, of course, you won’t want to leave them open in really cold weather. 

Rain cleans pollutants from the air and flushes them to the ground or into a storm sewer. Rainy weather is a good time to leave windows open at least a crack.

You can put a box fan in an open window where air is flowing out and point the fan outside to exchange air faster.

You probably have exhaust fans in your kitchen and bathrooms that are vented to the outside. The exhaust fan above your stove may force air through a filter instead of sending it outside, so you will need to clean it from time to time.

For that matter, be sure to change your furnace filters regularly if you have a forced warm air system. They clean the air only until they become clogged. Don’t expect them to last for more than three months.

Turn on exhaust fans when you need them, but don’t let them run too long. Otherwise, you will make your furnace or air conditioner work harder than necessary. On the other hand, if your home has an attic fan, using it properly can help reduce your heating/cooling bill. 

A ceiling fan improves air circulation and can work with, not against, your furnace and air conditioner.

Air purifiers

Some houseplants improve indoor air quality. Your home has lots of different contaminants, and many plants “specialize” in removing only certain ones. Having enough of the right kinds of plants to clean the air effectively all by themselves would use up all your living space. Still, they make an attractive start. Be sure not to overwater your plants, though. That can encourage molds to grow and trigger allergies.

You can also buy mechanical air purifiers. They come in especially handy if you have severe allergies and can’t identify what triggers them. They will probably remove all the same pollutants that your furnace filter does. 

On the other hand, my parents’ home has a boiler and hot-water heating system instead of forced warm air. If you don’t have a ventilation system that requires a filter, an air purifier becomes more important for maintaining home air quality. But like the furnace, the filters in your air purifier need to be replaced or cleaned regularly. 

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Sources:

13 ways to reduce indoor air pollution / Suzanne Norris, Good Housekeeping. April 6, 2023 
Do air purifiers actually work? / Rachel Rothman, Good Housekeeping. May 2, 2023 
The inside story: a guide to indoor air quality / US Consumer Products Safety Commission 
Introduction to indoor air quality / US Environmental Protection Agency