Pollution can be 5 to 10 times worse in your home than outside. Here’s what to do about it

Homes are at the center of our major health crises. They’re also a big part of the solution.

Pollution can be 5 to 10 times worse in your home than outside. Here’s what to do about it
[Photo: maruco/iStock]

This story is part of Home Bound, a series that examines Americans’ fraught relationship with their homes—and the once-in-a-lifetime opportunity to hit the reset button. Read more here.


During the pandemic, many of us felt like we were trapped inside because, well, we were. But this actually isn’t all that unusual.

The typical person in the United States spends 90% of their time indoors during any given year. We’ve become an indoor species. About two-thirds of our life is spent at home, with the rest of the time divided between places such as work and school, and things such as getting groceries, doing errands, and going to the gym, the bank, and church. It also includes the time we spend getting to and from those places, which, for most people, also involves more time inside—cars, buses, subways, and airplanes.

So what was different this year was not how much time we spent indoors, but where that balance shifted. Instead of schools and office buildings, many people spent more time at home. A lot more.

All that time at home—just as COVID-19 was sharpening our focus to the importance of indoor air—means people are now, maybe for the first time ever, paying more attention to what life inside four walls means for their health.

The focus right now is on infectious disease avoidance, and rightly so. But there’s a lot more happening in your home that should catch your attention. Creating a safe and healthy home means paying attention to the air indoors. More fresh indoor air is associated with better cognitive function; indoor nature is associated with higher scores on creativity tests; and better air quality, acoustics, and lighting control can help with sleep quality.


But as the pandemic has shown, poor air quality doesn’t impact everyone equally. Where homes are located, how they’re built, and what’s inside them have a huge impact on our health—and can vary dramatically from one household to the next.

Hidden toxins

Indoor air pollution can be 5 to 10 times higher than outdoor air pollution, or worse. When you cook without an exhaust running, particles that come off your frying pan can make the air in your kitchen hit levels that you might see in Beijing on a bad air-pollution day.

Then there’s radon, a radioactive gas that seeps into our homes from the ground below and is the second leading cause of lung cancer. About one in 15 homes has radon at the “action” level—a level where the lifetime risk of lung cancer is almost one in 100.

There’s more. Flame-retardant chemicals commonly found in your couch, carpet, and other consumer products come out of those products into the air and dust in your home, and they end up in your body. They can wreak havoc on thyroid and sex hormones, and they reduce the likelihood of becoming pregnant and having a live birth for those undergoing fertility treatments.

So-called “Forever Chemicals” that are used on carpets for stain resistance and as surface coatings on nonstick pans are associated with testicular cancer, kidney cancer, and reduced vaccine effectiveness in kids. Some 98% of Americans have these chemicals in their body. In a study of a weight-loss program, women with higher levels of these chemicals gained back more weight and gained back weight faster.


It’s not just the air and dust—what’s in our water matters too. Take those Forever Chemicals—they are in the drinking water of tens of millions of Americans above the “safe” level. That’s on top of all the lead from old pipes.

Creating a healthy home

It can be overwhelming to think about totally upending your home life to clear out toxins you didn’t even know existed. But it doesn’t have to be complicated, and it doesn’t necessarily require spending a bunch of money or buying new fancy technology. A healthy home is really about getting back to the basics: air, light, water, safety.

It actually starts right at the front door: kicking your shoes off before you come in so you’re not bringing dirt and heavy metals from the street into your home.

There are also things you can do in each room of the home. Some are basic—such as making sure you have a fire extinguisher, smoke alarm, and carbon monoxide detector—and some you may not have thought about much, such as how volatile chemicals in scented cleaners and air fresheners can react with ozone to create formaldehyde and other harmful pollutants in your home. (For a full list of ways to navigate your indoor air, we put together a report with 36 expert tips.)

Unequal air

The health impacts of unhealthy homes—and an unhealthy climate—aren’t evenly distributed. The pandemic has further exposed what has existed for a long time—shocking disparities in terms of illness and death, with communities of color and low-income communities suffering disproportionately. A recent study by the CDC found that the risk of death from COVID-19 was two times higher, and the risk of getting infected was three times higher, for Black and Hispanic/Latino people.


The risk factors include working conditions and social determinants, but also differences in housing quality. Significant racial gaps exist in housing quality and home ownership due to, among many other racist policies and practices, historic redlining that has left Black and brown communities intentionally underinvested in. Low-income housing is typically smaller, denser, and not as well maintained, leading to a higher risk from infectious diseases, more pest infestation, exposure to mold, and legacy hazards such as asbestos and lead paint.

It’s not just what’s happening in the homes where we see disparities—it’s what’s happening around them too. Redlining and historic underinvestment in minority communities has led to stark differences in outdoor air quality and access to nature. There are fewer parks and less green space in lower-income and minority communities, and more pollution from roadways, contributing to higher rates of asthma.

Rethinking pollution

When we think about air pollution, we tend to think of the emissions from cars and smokestacks in the big power plants generating our electricity. But as the energy grid gets cleaner by moving toward renewable sources such as solar and wind, the contribution to climate change from our homes won’t be from these large power plants. It will be from on-site fossil-fuel combustion, where large swaths of the country rely on the burning of natural gas, oil, and other fuels for heating.

Our global energy system is dominated by fossil-fuel combustion, which releases air pollutants that have an immediate impact on our health, including increasing the risk of mortality and cardiovascular disease. This can manifest in more missed school days, more missed workdays, more asthma attacks, and more hospital visits. There are also long-term health effects as these pollutants change our climate, creating more severe storms, longer droughts in some areas and more flooding in others, and vast disruptions to our food and natural ecosystems. Buildings, as consumers of 40% of that global energy, play a major role in this problem. Homes account for about 20% of greenhouse gas emissions.

There are several proposed solutions. California has mandated solar panels on all new residential construction. That can help reduce demand on the electrical grid, but what about the on-site combustion of fossil fuels? Here, there’s a move toward electrifying everything in our homes—gas stoves, hot water heaters, boilers. All of the systems that rely on fossil fuels. That way, when our homes are drawing on clean electricity—from solar panels to massive wind farms—we won’t be left with burning fossil fuels in our buildings. Here, too, communities across the country are starting to take action. In 2019, Berkeley passed an ordinance banning natural-gas hookups in most new construction. Colorado, Massachusetts, and Washington state are considering similar proposals.


Putting this all together, homes are at the center of our major health crises. Which means they are also at the center of the solution. The future of healthy homes must be one where healthy buildings are the norm for all. And it shouldn’t be a luxury item for only those who can afford it, because a healthy home is a human right.

Joseph Allen is an associate professor and director of the healthy-buildings program at Harvard T.H. Chan School of Public Health. He coauthored Healthy Buildings: How Indoor Spaces Drive Performance and Productivity.