Air Quality

How To Fix Dry Air, Humid Air, And Improve Indoor Air Quality

You might want to blame daycare, or your colleagues, or kids who don't wash hands for getting your family sick. But there's a far more likely culprit.

Originally Published: 
A dad fixes an air conditioner filter at home.
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We often think of air pollution as car exhaust, smoke-spewing factories, and smog, but the air your family breathes while sleeping, eating, and vegging in front of the TV is anything but clean. Indoor air is teeming with toxic chemicals and allergens that can singe the eyes, trigger asthma attacks, and bring on headaches. Over time, airborne toxins can disrupt hormones, damage vital organs, and possibly even lead to cancer.

But pollution isn’t the only problem lurking in the air. Homes that are too dry are a potential health hazard too. Along with causing cracked skin and nosebleeds and increasing the risk of dehydration, overly dry air keeps influenza aloft — and makes us more likely to get infected. But on the flipside, too-humid air encourages mold growth and attracts dust mites, creating a whole new set of health problems.

Whether polluted, too dry, or too humid, imperfect indoor air is likely making your family sick. So what can you do about it? Contrary to popular demand, the answer to the pollution problem is not to fill your home with potted plants. They do purify the air very slightly, but you’d have to turn every room into a jungle to have any meaningful effect.

Here are some more real, actionable solutions to keep your family safe from illness both now and in the future.

The Indoor Air Problem: Pollution and Allergens

“Believe or not, indoor air is actually more polluted than outdoor air,” says Josh Jacobs, director of environmental codes and standards at independent safety certifier UL. “Because we seal up buildings and control ventilation rates, anything we add inside — drywall, flooring, furniture, paint, electronics — can give off VOCs, which do not dissipate in an indoor environment.”

Short for volatile organic compounds, VOCs include some 13,000 toxic chemicals, such as formaldehyde, aldehyde, benzene, and toluene, which come from manmade household products and building materials. In fact, Jacobs says that only items made entirely of steel, glass, concrete, or stone do not give off VOCs that we then breathe in.

Along with irritating the eyes, nose, and throat, these hazardous chemicals can worsen asthma symptoms and cause dizziness, nausea, headaches, skin rashes, and fatigue. Prolonged exposure can harm the kidneys, liver, or central nervous system and potentially cause cancer.

Although plenty of VOCs are emitted outdoors, those chemicals can escape, whereas the VOCs given off inside the home get trapped, turning problematic. “Think about it like red dye,” Jacobs says. “If you put one drop in the ocean, it will dissipate quickly and nothing will really happens. But if you put one drop in a fishbowl, it will turn the water pink or even bright red.”

Besides VOC contamination, indoor air can also be sullied by allergens such as pet dander, dust mites, mold, or even pollen tracked in from outside. Along with hovering in the air, these pollutants accumulate in house dust. What’s more, everyday activities like cooking on a gas stove and scouring the kitchen floor release gasses that can cause health problems when inhaled.

How to Fix It

You’ll never totally eradicate VOC emissions, but you can do a lot to lessen your family’s exposure, starting with the types of products you bring into your home. When shopping for paint, furniture, countertops, drywall, mattresses, bedding, window treatments, and many more home-improvement needs, look for UL’s GreenGuard Gold certification. Any product bearing this seal will have passed rigorous third-party testing to prove it has low VOC emissions.

Similarly, for carpeting, flooring, and the adhesives and sealants they require, pick products that carry the Carpet and Rug Institute’s Green Label Plus seal, which have also passed UL’s stringent VOC emissions tests. Another certification to know is ECOLOGO, also administered by UL, which signals low VOCs as well as a minimal environmental footprint. Look for this seal on cleaning products especially, but also paper products, electronics, office equipment, and more. (For a full list of certified GreenGuard, Green Label Plus, or ECOLOGO products, go to UL Spot.)

To lessen the VOC threat from household items you already own, open windows as much as possible to circulate outdoor air through your home. If you have a forced-air heating and cooling system, use filters designed to remove small particles (Check Consumer Reports’ Air Filter Buying Guide for best options) and change it out regularly; this should help minimize airborne allergens as well. Also consider a standalone air purifier, which won’t do much for VOCs but can capture allergens, dust, and other particles. These require regular filter swap-outs too.

Additionally, vacuum, sweep, and dust your entire home frequently to mop up all the allergens and other nasty stuff that’s settled onto floors, furniture, and electronics. And if you have a gas stovetop with an exhaust hood, use it whenever you cook and leave it on for a few minutes after you’re done. Research shows that hoods drastically limit the pollutants pushed into the air.

The Indoor Air Problem: Dry Air

If you live in the northern U.S., at high elevation, or anywhere that gets cold enough to necessitate turning on the heat for part of the year, dry indoor air is practically a given. The Environmental Protection Agency advises keeping humidity levels between 30% and 50%, but rarely do homes with the heat running constantly even scratch 30.

Some of what happens when the air is too dry is obvious and annoying: scaly skin, staticky hair, itchy scalp. Nosebleeds are common as well, because when the tiny blood vessels in our nasal passageways dry out, they become brittle and burst easily. But dry air introduces more health hazards than many people realize. First, it’s easier to get dehydrated because the body loses fluids while we breathe. And along with causing headaches, dizziness, or nausea, dehydration can make us more prone to respiratory ailments.

“Our immune system relies on a certain amount of moisture to create thick, gooey mucus that traps viruses and bacteria in the nose and mouth before they can infect us,” says Daniel Allan, M.D., a family medicine physician at the Cleveland Clinic. “Those secretions carry antibodies so they work almost like a filter. But if you’re not well hydrated, your nose and mouth will dry out, leaving you more vulnerable to illness.”

Making matters worse, some viruses — especially influenza — thrive in dry air. Research shows that flu epidemics in the U.S. almost always come a few weeks after the relative humidity drops. This is likely because dry air helps the virus to travel better and stay activated longer, says Jennifer Reiman, Ph.D., who researched humidity’s effects on influenza while at the Mayo Clinic.

“As soon as someone sneezes or coughs, the [influenza-containing] droplets they expel start shrinking,” she says. “Under low humidity, they shrink more rapidly, and when they are smaller, it takes longer for them to fall out of circulation and onto the floor. They hang around in the air longer and are more easily picked up by others.” Those smaller particles can reach deeper into the airways and get into the lungs where they can infect, Reiman adds, whereas bigger particles don’t make it as far into the body.

How to Fix It

To keep your home from drying out, make sure it’s well insulated. “The more air leaks you have in your doors, windows, crawl spaces, and weather stripping, the more dry, cold outdoor air comes into the home,” Allan says. “Then the furnace has to work harder, making it harder to control humidity in the house. Insulating well is good for your monthly energy bill but also could help reduce your chances of getting sick.”

If you suspect the humidity in your home is too low — and again, even if your house is sealed well, if the heat has been on for a while, the humidity probably is too low — first buy a hygrometer to test it. These instruments are sold at most hardware stores or on Amazon, often for under $20. If the humidity level reads below 30%, then consider buying a humidifier, which shoots a fine mist of water into the air to bump up the moisture level. There are console units, which are generally bigger, stay parked in one spot, and can treat the air of a large space, as well as tabletop humidifiers, which are smaller and easier to move from room to room. Depending on the size and layout of your house, you might need more than one unit.

When it comes to flu protection, humidifiers have been proven to help. Reiman ran a fascinating study a few winters ago in which her team installed humidifiers in two preschool classrooms to raise the humidity level to between 42% and 45%. They left two other classrooms untreated. Then, along with tracking the number of kids who reported flu symptoms that year, the researchers collected air samples from each classroom and swabbed wooden blocks, markers, playdough utensils, and other surfaces the tots touched.

Analyzing all the samples in their lab, Reiman’s team found significantly more influenza present in the classrooms without the humidifiers. And of the virus samples found, those from the drier rooms were more virulent. This synced up to the data from the kids, as 2.3 more cases of influenza-like illness were reported from the non-humidified classrooms.

Although they can make your home feel more comfortable and decrease virus risk, be careful with humidifiers. They require refilling daily and a deep cleaning at least once a week to ensure they keep working efficiently and, more importantly, to prevent mold from forming and bacteria from building up in the stagnant water — you don’t want that junk misting into the air.

The Indoor Air Problem: Too-Humid Air

With humidity, too much of a good thing is very, very bad. Although indoor air above 50% humidity is more common in the Southeastern U.S., it can happen anywhere that gets hot and humid in the summertime — or whenever a home’s air conditioning system isn’t working properly. Basements, bathrooms, and very small spaces can see humidity levels creep too high.

Homes that are too humid risk sprouting mold, which produces allergens that can cause sneezing, runny nose, watery eyes, skin rashes, and feverlike symptoms. Mold is particularly pesky for people with asthma, upping the risk of attacks. Another common allergen, dust mites, thrive in humidity as well. So do many species of bacteria that can make us sick. Oh, and here’s one more problem: Research shows humidity higher than 60% can increase concentrations of VOCs.

How to Fix It

If your home is harboring unhealthy humidity levels, you’ll likely be able to feel it — and notice condensation on windows and mirrors. But it never hurts to bust out the hygrometer to check.

To keep levels under control, get your air conditioning looked at by a professional to ensure that you have the most efficient system for your home and that it’s working as it should. Also, make sure to use the exhaust fans over your stove and in your bathrooms to draw out excess moisture. Run fans in your home to keep air circulating and humidity low. Even taking shorter showers and covering steaming pots on the stove will help stop humidity from rising.

If humidity is an ongoing problem, consider investing in a dehumidifier, which sucks moisture from the air, collecting the water in a removable reservoir. Dehumidifiers come in multiple capacities based on how many pints of water they can draw from the air within 24 hours. Your home or room’s size and current humidity level can inform how strong of a horse you need. (Consumer Reports offers a comprehensive buying guide and product reviews.)

Just like with a humidifier, though, you have to stay on top of cleaning dehumidifiers or you could have a pool of bacteria before long.

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