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Time Magazine
2 days ago
- Health
- Time Magazine
Can Air Conditioning Make You Sick?
At the height of the tuberculosis epidemic in the 19th century, doctors began advising people to venture outside to escape the ' bad air ' in their homes. In the 1960s, by contrast, AC became widespread in the U.S., increasing the appeal of staying inside. These days, many of us—the so-called ' indoor generation '—spend summer mostly inside, relying on AC to beat the heat. This technology saves lives; our sealed, climate-controlled spaces keep us healthy during dangerous heat waves. AC also helps many people avoid pollution outside. But did the 19th century physicians have a point about the downsides of stale indoor air? It depends. 'Multiple studies show that spending too much time in air-conditioned rooms can lead to more respiratory symptoms,' says Dr. William Checkley, a pulmonary and critical care physician and professor of medicine at Johns Hopkins School of Medicine. Here are the benefits, risks, and simple ways to make AC healthier this summer. The many benefits of AC AC is key to getting through summertime without a heat-related illness—or worse. 'The statistics on deaths from extreme heat are shocking, especially for the elderly and immunocompromised,' says Jeffrey Siegel, professor of civil engineering at the University of Toronto. From 1999 to 2023, heat-related deaths in the U.S. doubled. AC's benefits go beyond its cooling effect. A well-working AC system filters the air to reduce intake of dust, pollen, and airborne pathogens, Checkley says. AC is also critical in areas with pollution. Its filters can cleanse the air of particulate matter 2.5, a toxin shed in vehicle exhaust, industrial activity, and wildfires. Research shows that PM2.5 enters homes and contributes to heart and lung disease—but these effects aren't as severe in places with more AC use. 'Every time the AC system operates, it's pulling some particles out of the air,' says Brent Stephens, professor of civil, architectural, and environmental engineering at Illinois Institute of Technology. Cranking up the AC also makes the air less humid, reducing the dampness that contributes to bacterial growth, mold, and dust mites, which can contribute to—or, in rare cases, even cause—conditions like pneumonia, asthma, and COPD. Too much of a good thing Now, some big caveats. If you overdo it with AC, the air becomes too dry. If you're inhaling a lot of dry air, the human body adds water vapor to the inhaled air to maintain your internal humidity level, Checkley says. When you exhale, that moist air leaves your body with every breath. Ultimately, this dries out your respiratory tract, Checkley explains. The airways become irritated and inflamed, causing coughs, sore throat, and nasal congestion—a condition known as ' sick building syndrome.' Another consequence of air that's too dry: the lungs' natural defenses to microbes weaken, increasing susceptibility to disease, especially among kids and the immunocompromised. Viruses may be more likely to circulate in drier conditions. Think of how often people get sick right after long trips inside a dry airplane. It's the same effect in people's homes or offices. This may seem like a no-win situation: dampness leads to mold and dustmites, and dryness leads to cold-like symptoms and disease. However, there's a sweet spot. 'The ideal humidity in a home is between 40% and 60%,' Checkley says. Bacteria and viruses thrive both below and above these thresholds. 'There are indoor air conditions we can't perceive, which can be good or bad for us—it's not all about comfort,' says Dr. Stephanie Taylor, a clinician and consultant on healthy indoor environments. So how do you keep your home in the optimal humidity zone? Checkley advises buying a thermostat with a humidity sensor, called a hygrometer, to track the level. Many are inexpensive yet accurate. If humidity drops below 40%, give the AC a rest. If humidity tops 60%, crank it back up. Maintain your unit The AC may also pose health risks if it's working sub-optimally, even if it's not outright broken. 'What really matters is the condition of your air conditioning,' Siegel says. Much of this comes down to homeowner fundamentals like remembering to change your AC filter. With an old dirty filter, the AC coil and ducts could become 'cesspools of mold, bacteria, and allergens,' Taylor explains—which tag along with the AC's airflow. Slide in new filters every 1-2 months during peak AC use. The cost of additional filters is worth keeping up your home's air quality, Checkley says. Look for filters with minimum efficiency reporting value (MERV) ratings of 11 or 13. They're effective at trapping dust, mold, and other particles. In addition, calendar a yearly visit from an HVAC specialist. 'People think of AC as this magic black box that makes cold,' Siegel says. 'We only think about servicing it when it's not making cold anymore.' Even if the cold magic still works, a specialist should occasionally inspect the coil and ducts to ensure they're clean. In addition to regular assessments, get one after any major leak or other moisture problem, which can result in a dirty coil, Siegel adds. You can also install a UV light in your AC system. This device emits radiation that damages the cells of microorganisms like bacteria and mold—keeping the coil and interior components clean. Quality varies; make sure to work with a reputable manufacturer and contractor, and choose a light with a safety certification from UL or ETL, two independent organizations that test and certify products like lights for safety. Lights without these certifications may generate harmful byproducts, Taylor notes. Proper AC maintenance will also amplify AC's benefits, like thinning out PM2.5 from the air. 'With a decent filter, you reduce exposure to a ton of things we know have very serious health effects,' Siegel says. For a window AC, don't move it straight from the closet to the window when summer starts. 'Open it up and clean it first,' Taylor says. Use air purifiers Although your AC can—if it's working on all cylinders—clean PM2.5 pollution from outdoor sources, it does not clean another type of toxin that originates inside the home: volatile organic compounds, or VOCs. If the AC is on constantly, and you rarely open windows, your air may be rife with these chemicals. Potentially harmful VOCs are emitted by many home products such as furniture, cleaning supplies, and air fresheners. They've been linked to headaches, throat irritation, hormone disruption and, with long-term exposure, chronic diseases. VOCs play a role in what experts increasingly view as a building's microbiome, Taylor says. Indoor spaces, just like the human body, harbor communities of bacteria, fungi, and other microbes. With optimal humidity and AC maintenance, your indoor microbiome supports healthier, more diverse microbes. But VOCs can suppress or kill these microbes and promote the growth of pathogenic strains and imbalanced communities. Counter toxic VOCs by occasionally turning off the AC and opening windows. Indoor air has 2 to 5 times more VOCs than outdoor air, Stephens says. Another strategy: buy a portable HEPA air purifier. The best versions have carbon filters with porous surfaces that trap the gas molecules of VOCs, taking them out of the air. Purifiers also help remove about 50% of PM2.5. Stephens has one purifier on each level of his townhome. He keeps the purifiers' fan speeds on low or medium constantly to filter the air without having to think about it—but changes the speed to high when there's pollution, such as during rush hour when PM2.5 comes from outside, or when he's cleaning with chemicals that produce VOCs inside. VOC levels may be higher if your home is tightly sealed, trapping the chemicals inside. 'Every home is an absolute unicorn,' Stephens says. A professional air sampling measures VOCs. A number of VOC monitors are also available for people to buy, but Stephens says these consumer-grade devices can't detect levels of specific VOCs, so they won't tell you the potential toxicity or health risk. However, he adds that low-cost monitors for particles like PM2.5 have become much more accurate in recent years. An even less expensive, relatively simple humidity monitor combined with good AC maintenance will help ensure that you stay both cool and healthy this summer.
New York Times
13-03-2025
- Health
- New York Times
What Is Dust Even Made Of? (And How to Manage It)
Cut down on items in your home that hold on to dust and allergens. This is the first preventive step. Carpet, upholstered furniture, drapes, and linens all hold on to dust, so the less of them you have in your home, the better for your allergies and breathing. Frequently wash your bedding and linens. We recommend washing bedsheets about once a week and changing towels every three days or so. This is especially important if you have pets. Dust regularly. Rather than using something like a feather duster, which ends up redistributing dust onto other surfaces or into the air, the American Lung Association recommends damp-dusting. I like to use a microfiber cloth dampened with all-purpose cleaner to dust most flat surfaces in my home, and I tackle corners and crevices with a handheld vacuum. Michael Hession/NYT Wirecutter Instead of using a feather duster, which flings dust back into the air, use a damp microfiber cloth to wipe down surfaces while trapping dust. $5 from Amazon (pack of eight) Because cleaning can agitate dust and recirculate it into the air, Checkley recommends that you open windows while cleaning; those who are exceptionally sensitive to dust can also wear a well-fitting N95 mask to avoid inhaling fine particles. Work from the top of the room (tackling overhead fans and the tops of picture frames, for example) down, since dust settles. Buhr also encourages people to run their HVAC system for a few hours after cleaning to suck stirred-up dust into the filtration system. You should also want to change your HVAC filters every three months, he says. A typical house cat might shed 75,000 hairs a day. A robot vacuum can help manage all that fur between deep cleans. Vacuum regularly to help reduce the amount of dust in your home. This is particularly important if you have shedding pets. Checkley recommends using vacuums with HEPA filters to trap dust particles, though home-improvement senior staff writer Liam McCabe, who previously reviewed vacuums for Wirecutter, found that HEPA filters aren't a cure-all for reducing your exposure to kicked-up dust while you're vacuuming. Marki Williams/NYT Wirecutter Although HEPA filters are certainly the gold standard, they can filter only what they touch, and many vacuums have air gaps that allow fine particles to travel around the filter or spew out from the vacuum's seams before the filter catches them. 'Depending on your goals and expectations for your indoor air quality, an expensive upgrade isn't always necessary,' Liam says. In general, it's better to clean carpets and upholstery even with an imperfect vacuum than to just let the dust pile up. We have recommendations for the best vacuums if you are shopping for a new one. Buhr also suggests emptying vacuum dustbins outdoors directly into the trash can to reduce exposure to the cloud of dust that often puffs up as you empty it. Run an air purifier to cut down on dust buildup. An air purifier can also help reduce the allergic reactions that dust triggers by filtering airborne allergens, mold spores, pollen, bacteria, and smoke from the air. Under typical conditions, Wirecutter recommends running your air purifier 24/7 on the 'quiet' setting, which is generally the medium setting on three-speed purifiers or the high-medium setting on four-speed machines. Dedicate a purifier to each room in your home and place it at least 18 inches from a wall and any furniture, ideally near the midpoint of the room you're using it in. Connie Park/NYT Wirecutter Although people might never fully win the war against dust (and those pesky mites), you can certainly keep dust at bay with some targeted cleaning and preventive measures. That's good news, too, because I don't want to think about all the dead skin cells and potential allergens floating around my home, even if it is a fact of life. This article was edited by Katie Okamoto and Megan Beauchamp. Get cleaner air in a range of room sizes with air purifiers we've tested and measured firsthand. Microplastics may contribute to heart disease, lung disorders, and other health problems. Use these 12 tips to reduce your exposure. For a dependable, versatile, and affordable cleaner, we prefer a bagless upright, but we have recommendations for other types of vacuums as well. Most microfiber cloths are essentially the same, but after weeks of testing, our cleaning writer liked Fixsmith Microfiber Cleaning Cloths best.
