A 3D rendering of a livingroom with a white rectangular air purifier near three large windows with streaks of airflow...
Photograph: Junho Ji/Getty Images
I spent this past summer in a cabin in Maine. There, I continued to review gear for WIRED. I tested air purifiers, food dehydrators, and indoor air quality monitors. I kept track of outdoor air quality, monitored the indoor air, and watched the numbers climb in their predictable pattern when I used the stove.
A couple weeks into my air quality cabin experiment, I noticed odd spikes in PM 2.5 for seemingly no reason. PM 2.5 are those invisible particulates that can enter the deepest parts of the lungs and then the bloodstream. They contribute to negative health outcomes like heart attacks, hypertension, and respiratory issues, to name a few. I hadn’t been cooking; I hadn’t done anything. The PM 2.5 numbers, illuminated on various air quality monitors, climbed from 4 to 24 to 75 or higher. My air purifiers’ internal sensors, some using the same technology as my air quality monitors—a tiny chamber where a beam of light scatters picking up the particulates, even the invisible PM 2.5—automatically cranked up their fans. And all I did was walk across the room.
It was the rug!
The first time I heard about the dangers of household rugs and carpets was from air pollution researcher Shelly Miller at the University of Colorado in Boulder, whom I interviewed for my first story on air quality; namely, how to get good air in my 100-year-old Brooklyn apartment. Miller was the one to introduce me to the term resuspension. Resuspension is exactly what it sounds like: Dust and particulate matter in carpets take flight when kicked up by footsteps. The same thing happens with upholstery. Plop down on a sofa and you might see a puff of dust. I have an air quality monitor next to my bed, and I’ve seen the uptick in PM 2.5 when I move my weighted blanket over my duvet. We dust, vacuum, and wash fabrics not just for aesthetics; it’s also for our health, and more pointedly, our hearts.
It's In the Cloud
I had forgotten about resuspension and let my no-shoes-inside-rule slide at the cabin. By the time I made the connection, I had taken the two carpets outside to hit them old-style with a broom. Giant plumes of dust flew into the air. I had brought my six-year-old HEPA-filtered Dyson stick vacuum with me, but in the end I rolled up my rugs, put them away, and chose to sweep and mop the wood floors instead. My indoor air quality improved.
I reached out to indoor air quality researcher Andrea Ferro of Clarkson University and asked her about how to clear the air of the scourge that is resuspension from carpets. She pointed out that HEPA air filters are up to the task: “We resuspend dust all the time. It’s a normal component of indoor air.” When I asked how high the dust lifts, she told me, “Resuspended dust easily reaches breathing height and mixes throughout the air in the room.” And this isn’t just about being tidy. There are health benefits—cardioprotective benefits that go with having good air.
When I first told Jonathan Newman, director of Clinical Research at The Center for the Prevention of Cardiovascular Disease at NYU Langone Health, about my poor indoor air, he mentioned a study he worked on in New York City public housing aimed at quantifying the health benefits of good air. And indoor PM 2.5—resuspended or otherwise—is something that HEPA filters can clean. Dr. Newman pointed out that air purifiers “appear to reduce blood pressure by approximately 3 to 4 mmHg over various time intervals.” And while lowering one’s blood pressure by three points might seem like a small number, Dr. Newman offered the view of seeing it in terms of how we improve our health through diet. Lower one’s indoor PM 2.5 “is also about what we see with dietary approaches to lower sodium and blood pressure.”
And what can thwart those efforts? Carpets. They can be our own bad air farms, cycling through the collection of PM 2.5 only to send it airborne once again. Vacuuming with a HEPA filter vacuum can mitigate some of the issues with resuspension. Unfortunately, using a hand-me-down vacuum without a HEPA filter will make matters worse. You’ll end up churning those tiny particulates into even tinier ones that will then be spit out into the air by orders of magnitude. And everyone needs an air purifier. This could take the form of the MERV filters in an HVAC system or portable air purifiers, like the ones I review for WIRED. And a separate air quality monitor will keep tabs on general indoor air quality. Resuspension is part of that, but the best thing to do? Toss the rug.
But what if you want to keep your carpet? Maybe it matches the drapes, has sentimental value, or your condo requires you to cover 80 percent of your floors for sound buffering? If that’s the case, how does one combat the health hazards that lie beneath our feet? And it’s not just dust. The more I looked into resuspension, the more I learned about carpet’s other danger: One that has potential to harm more than just our hearts.
Wall-to-Wall Pitfall
Carpet fibers and treatments like stain-resistant coatings or flame retardants can contain per- and polyfluoroalkyl substances (PFAS). And it’s not just during resuspension that humans can inhale and/or ingest those PFAS. Exposure to PFAS, known as forever chemicals because they take centuries to break down, have been identified as a risk factor in a myriad of cancers. I reached out to researcher Scott M. Bartell at the University of California, Irvine, after reading his recent study showing how low-pile carpet usage was consistently associated with higher blood PFAS concentrations than bare flooring. And he had an even bleaker take on what we keep in our homes.
Bartell emailed me, telling me “many other studies linking PFAS exposure to a variety of health problems including cancer, decreased antibody response to vaccines, and increased cholesterol and triglycerides, and our dose-response analysis for kidney cancer and others for antibody response have showed that health risks are increased even at very low doses, indicating that there might not be any safe level of exposure for these toxicants.”
And when I asked Bartell about PFAS in the air, he clarified, “The exposure from carpeting is likely mostly from ingestion (including small airborne particulates that get swallowed), rather than skin contact, but researchers are still trying to understand that better.” In fact, he’s currently doing a study right now analyzing dust and air samples in peoples’ homes to try and answer that question. And, as studies and Bartell reminded me, most PFAS exposure comes from dietary intake, like drinking water contaminated with PFAS.
Still, Big Carpet, officially the Carpet and Rug Institute, or CRI, has known about the PFAS problem. It even has its own Green Label Plus label to certify the lowest-emitting VOCs in carpets. Carpets that contain those PFAS, either in the fibers themselves or in the treatments, can off-gas those PFAS as volatile organic compounds, or VOCs. The CRI uses a third party to test carpets, adhesives, and cushion products for the lowest emissions. And if you want to buy a carpet and it doesn’t have Green Label Plus, the next best thing is a label that complies with California Section 01350 Compounds textile compliance.
What if your carpet has neither of those labels, but you want to remove the VOCs it’s emitting? A HEPA filter won’t be enough. Researcher Ferro explained, “PFAS compounds have a range of volatility. For all PFAS compounds, source control/reduction is the best approach. In other words, try to remove the products that emit PFAS from your home.” But what if you already bought the carpet? Ferro told me, “You can remove PFAS from dust on surfaces via cleaning and from the air via ventilation and filtration. For the gas phase, the best removal method is ventilation. Activated carbon filters do work to remove volatile PFAS from the air.” The majority of air purifiers that I review come with activated carbon filters.
Cleaning Crew
When I returned home to Brooklyn, I was on a mission to make sure my indoor floors couldn’t make me or my family sick. I had no idea what my apartment’s carpets were made of, nor did I know if they were treated with stain or fire repellent. I threw out the area rug in my boys’ room and replaced it with a 5- by 8-foot washable wool rug from Revival ($349). I chose the new natural fiber Catlett design because it was washable, wasn’t treated with stain or fire repellant, and complied with California Section 01350 Compounds textile compliance. In short, it was PFAS-free. I loved the soft, high-pile fibers. Testing its washability, I took it to my local laundromat and gave it a spin in their large commercial washer and dryer. It held up well and only shrunk a wee bit, as the rug pad peeked out a bit along the sides after washing.
To keep my new rug from being a resuspension menace, I used the Dyson Gen5outsize cordless vacuum ($1,050). At over a thousand dollars, the Gen5outsize is Dyson’s most powerful stick vacuum. And while the vacuum's circular screen listing particle size (microscopic, fine, medium, and coarse) was a bust due to its illegibly small font, it had excellent suction. My new rug looked and felt clean of dust. It also comes with the oddly satisfying blacklight-esque Fluffy Optic cleaner head for hard floors that revealed pet hair, dirt, and dust that was invisible with the naked eye.
I also tested the Shark Detect and Empty Cordless Vacuum ($450). At less than half the cost of Dyson’s Gen5outsize, the Shark Detect has a HEPA filter and an LED light, but it doesn’t do anything close to the Dyson’s dirt-illuminating power. What the Shark does have is power. It’s cordless. And when it’s placed back onto the base, the debris canister is auto-emptied into the base container. The base can hold quite a bit. And while the Shark is effective on both hard floors and carpets, the base gives off a Brutalist vibe. And if space is at a premium, the Shark and its base might live loud and large in your home. Still, the price is right.
The Shark S1000 Steam Mop ($70) did a solid job cleaning my hardwood floors. The steam mop costs under a hundred bucks, and I used it post-vacuuming. If you’re not ready to cut the rug, at least there’s gear to keep it from hurting your air and your health. And lastly, the cheapest way to keep your air clean is removing your shoes when you get home.