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We know at this point in the pandemic that COVID-19 is less likely to spread outdoors. But unless you live in a region of the US that has temperate weather year-round, patio happy hours and fire pit hangouts are not always viable options. Another COVID wave could be on the horizon, and the reality is that indoor socializing poses health risks—even in your home. Fiberglass Industrial Fan
Humans need social interaction, and that need doesn’t disappear when nasty weather comes knocking. If you find yourself home alone on rainy days or are worried about feeling isolated come winter, it’s worth remembering that improving air quality is an easy and oft-overlooked way to help lower your chances of spreading COVID—or any harmful airborne particles or contaminants—when gathering indoors, according to the Environmental Protection Agency (EPA).
Ventilation has been a hot topic throughout the pandemic, and many experts agree we need to raise the standard for indoor air quality across the board—in our schools, offices, grocery stores, you name it. But even without the policy changes that would make a big difference in public spaces, there is a lot you can do to improve ventilation in your home.
Ventilation is the process of introducing clean air to an indoor space, either by bringing in outdoor air or installing filtration systems to clean the air. And with how much time most people spend inside, air quality really matters. The EPA reports that Americans spend around 90% of their time indoors. “The indoor environment shapes our health,” Stephanie Taylor, MD, a physician with a master’s in architecture who founded Building4Health to address this very issue, tells SELF. Taylor has dedicated her career to understanding how indoor environments impact our well-being, and she works with the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to create guidelines on indoor air quality.
The air in our homes and workplaces can have significant health implications: Indoor pollutants, including building materials, pet dander, mold and asbestos, and chemicals found in cleaning supplies, among others, can cause all sorts of issues. For example, common allergens like dust mites, roaches, and mold can lead to short-term irritation or full-blown asthma attacks in those who are susceptible. Meanwhile, some forms of bacteria build-up can set off respiratory diseases, while inhaling carcinogens like radon gas can potentially lead to certain cancers, according to the EPA. “You need to bring in more outdoor air to dilute those indoor pollutants,” Dr. Taylor says.
Ventilation can “reduce exposure to contaminants that are already present in the indoor air,” William Bahnfleth, PhD, a professor of architectural engineering at Penn State University who chairs ASHRAE’s epidemic task force, tells SELF. This in turn reduces the risk of infection if harmful pathogens are lurking, he says.
So, ventilation can aid in lowering your chances of contracting an airborne respiratory illness like COVID-19 if you’re sharing a space with a contagious person, and it can make you less likely to spread it if you don’t know you’re sick, especially when combined with other safety measures, like social distancing, masking, and frequent hand washing.
There are two basic ways to improve ventilation in your home: You can bring fresh outdoor air inside or you can clean the air that’s already indoors.
The easiest way to bring fresh air in? Open your windows to replace stale indoor air with fresh outdoor air. “I do it every morning and air the house out,” Dr. Bahnfleth says. You can do this year-round and with heat or air conditioning running, but Bahnfleth says relying only on open windows in those instances isn’t the most energy efficient way to ventilate your home. To maximize impact, the Centers for Disease Control and Prevention (CDC) suggests placing a fan “as close as possible to an open window, blowing outside.” (Yes, it might seem counterintuitive to have the fan pointing away from you, but Dr. Bahnfleth says pointing a fan out creates a sort of DIY exhaust fan, as opposed to forcing contaminated air to stay inside.) Dr. Bahnfleth also suggests turning on bathroom exhaust fans to bring more outdoor air in.
One important caveat, according to Dr. Taylor: If the air outside your home is visibly polluted—say, by vehicles or wildfires—opening your windows might pose additional health risks, and isn’t the best approach. (The same is true if you have seasonal allergies and pollen counts are super high in your area.)
To clean and filter indoor air, you have a few options, the first of which is investing in a portable air purifier.
If you’re aiming to lower your COVID risk, it’s important to get a model that has a HEPA (high-efficiency particulate air) filter. When used correctly, HEPA filters can capture more than 99% of airborne particles containing the COVID-19 virus, according to the CDC. Dr. Bahnfleth says he keeps an air cleaner with a HEPA filter in nearly every room in his house.
Many portable air purifiers list square footage in their product descriptions, which is a helpful metric—but not the be-all-end-all. That square footage rating is calculated using the purifier’s clean air delivery rate, or CADR. “HEPA filters are good because they give you the highest CADR for the unit of air going through,” Dr. Bahnfleth says. But this calculation assumes you have 8-foot ceilings, meaning an air purifier designed for 400 square feet won’t necessarily be sufficient for a 400 square-foot room with 11-foot ceilings.
Noise is also a factor. Dr. Bahnfleth recommends sizing up if you don’t plan to run your air purifier on its highest setting. “Most people don’t like the noise level when they’re on the high fan setting,” Dr. Bahnfleth says. “You should really give them a listen if you can.”
While getting an air purifier with all the bells and whistles may seem tempting, EPA guidance cautions against air cleaners that claim to “ionize” air because these can produce ozone gas. “I would not recommend getting an air cleaner that emits ozone,” Dr. Taylor says. “Ozone is very inflammatory for your airways.” Some air cleaners intentionally generate ozone, while others produce it as a by-product. Either way, you want to avoid it. In its indoor air quality guidance, the EPA writes: “There is no difference, despite some marketers’ claims, between ozone in smog outdoors and ozone produced by these devices.”
And if you have central air, Dr. Bahnfleth suggests swapping out the filters in your HVAC system for ones rated MERV 13 or higher. (A MERV [minimum efficiency reporting values] rating tells you how good a filter is at capturing small particles, and ASHRAE suggests using a filter rated MERV 13 or higher for air filtration. HEPA filters, for reference, are MERV 17 or higher.) Most hardware stores sell pleated HVAC filters, including HEPA filters, with MERV ratings listed on the package.
You can find all of our recommendations for the best air purifier for your room here. Below are a few standouts.
Coway's air purifier is great for rooms up to 361 square feet in size and has a four-stage filter that includes HEPA filtration of up to 99.9% of super-fine particles like viruses, bacteria, mold, and more. Plus, it does not emit ozone.
Ideal for small rooms up to 250 square feet, the Molekule Air Mini+ is ozone-free and can be paired with the brand's PECO-HEPA Tri-Power filter, which has a 99.7% particle-capture efficiency rate.
This ozone-free smart tower fan from Dyson also acts as a purifier, includes a sealed HEPA filter, and works well for larger rooms up to 600 square feet in size.
Another pick for small- to medium-size rooms is the ozone-free Levoit Core 300, which has a three-stage filtration system with a HEPA filter that captures 99.97% of 0.3-micron particles.
If you’ve ever poked around the air purifier section of Amazon (what, just me?), you might have seen HEPA air purifiers that are about the size of a water bottle. They look curiously like a wireless Bluetooth speaker and often feature in Twitter threads on safe air travel. The one I purchased promised a clean bubble of air measuring eight cubic feet, which sounds enticing…until you try to measure out eight cubic feet. I would practically have to wear one around my neck for my head to fit within eight cubic feet—and that’s if it even works.
“Small tabletop air cleaners can be helpful,” Dr. Bahnfleth says. “But what is your expectation as far as how much that’s going to reduce your risk?” Again, directionality and airflow matter here. “It could reduce it some if it’s pointed right at you,” Dr. Bahnfleth says. But he adds that a jet of clean air coming out of any air purifier—and especially one so small—will immediately mix in air from the room around you, so the “clean bubble” of air within a much larger space is probably not realistic. While it may help in some scenarios, Dr. Bahnfleth cautions against over-reliance on a product like this.
ASHRAE’s guidance suggests placing your air purifier in a spot where “its air intake is unobstructed by furniture and its outlet is able to move air as far as possible before being deflected or drawn into a return or exhaust grille” like a bathroom or kitchen fan. Dr. Bahnfleth says the key is to make sure air purifiers circulate clean air through the space, so don’t plug it in right next to a window or exhaust fan. Instead, put the air purifier in the middle of the room with clearance on all sides.
You can further direct airflow by running ceiling fans and or standalone fans that plug into the wall. “You can create an airflow pattern in a shared space by your choices about opening windows and placing window fans,” Bahnfleth adds. He suggests opening two windows: one to bring air in, and one to point a fan out for exhaust.
Ventilation can’t replace other precautions—especially masking. “There are more effective ways to prevent infection than trying to clean up a mess after it’s already occurred,” Dr. Bahfleth says.
In fact, wearing a mask in a room that also has an air purifier running dramatically lowers your risk of contracting COVID from a contagious person, even if they are not masked. One study published in The Journal of Infectious Diseases earlier this year found that combining a fit-tested N95 with an efficient HEPA air purifier in simulated a health care setting could nearly eliminate risk of infection. And in other scenarios, researchers have found combining masking with HEPA filtration is more likely to prevent infection than either measure on its own. Dr. Bahnfleth still always wears an N95 when teaching classes at Penn State. “Masks are still in as far as I’m concerned,” he says. “Wear them when you can if you’re really concerned about getting infected.”
Unless you have direct influence over policy, there isn’t a lot you can control in a pandemic aside from your own choices. But you can maintain a healthier indoor environment through ventilation. Making your air less friendly to the spread of COVID-19 will lower your chances of transmission, especially if you layer in other precautions. And while picnic season may be in the rearview for this year, you can take steps to make socializing at home that much safer.
SELF does not provide medical advice, diagnosis, or treatment. Any information published on this website or by this brand is not intended as a substitute for medical advice, and you should not take any action before consulting with a healthcare professional.
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