Home isn't just where the heart is. These days it's where everything is. We spend over 90 percent of our time indoors, according to the EPA. And even more during the pandemic.
So, it is disturbing to learn that the concentration of pollutants indoors can be two to five times more than what is found outdoors, and occasionally more than 100 times higher, according to EPA research. The more time we stay at home, the more daily life—home heating, cooking, cleaning, working, living—amplifies the possible pollution sources and the value of clean indoor air.
Indoor air quality is more important than ever before.
We've known for many years, from scientific research and longitudinal health studies, that inhalable particle pollution inside homes can create damaging short and long-term health consequences, including respiratory ailments such as Chronic Obstructive Pulmonary Disorder (COPD) and asthma, heart disease, cancer, and even dementia. Particles smaller than 10 microns can be inhaled and lodge in your lungs or respiratory system. The most damaging pollution, however, comes from fine and ultrafine pollution particles, PM2.5 (smaller than 2.5 microns in diameter), which can lodge deeper in lungs, heart, and circulate in your bloodstream.
According to the EPA, indoor air pollution is one of the top five environmental risks to public health. The World Health Organization considers PM2.5 the world’s single biggest environmental health risk. New research is showing that exposure to ultrafine particles can compromise cognitive functioning in children.
The US Department of Energy Office of Scientific and Technical Information reports that "Chronic exposure to elevated PM2.5 has the potential to damage human respiratory systems and may result in premature death."
The EPA monitors PM 2.5 in the environment through the Air Quality Index, issuing warnings when outdoor air quality is poor. There is no equivalent standard for indoor air quality.
And then there's COVID-19 to consider. Recent studies implicate PM2.5 in more severe COVID-19 disease outcomes. One from Harvard University concluded "A small increase in long-term exposure to PM 2.5 leads to a large increase in the COVID-19 death rate."
A growing body of literature points to respiratory health strategies—from learning how to breathe effectively to eliminating particle pollution exposure—as some of the best ways to increase your resilience in the COVID-19 world. “Increased pollution increases susceptibility to infection,” said Dr. Meredith McCormack, a spokeswoman for the American Lung Association and associate professor of pulmonary and critical care at Johns Hopkins University. “All things being equal, a person exposed to air pollution would likely have a worse outcome if they were exposed to coronavirus.”
So, what's causing poor indoor air quality? That depends on how you live and where.
Most indoor pollution comes from indoor combustion sources including tobacco smoke, wood and coal heating, cooking appliances (especially gas-powered), fireplaces, space heaters, and even candles. The fine and ultrafine particles (PM 2.5 and smaller) introduced from these sources are not visible to the human eye, but the damage they can cause is real.
Maybe no one smokes, indoors at least—and that's good since we've known for a long time about the dangers of secondhand cigar and cigarette smoke. But what about cooking? It turns out your healthy, home-cooked roast chicken, fresh-from-the oven sourdough bread, and sizzling stir fry create indoor air pollution—both ultrafine particles and nitrogen dioxide. Cooking in general increases particle pollution; gas stoves are recognized as a dangerous source of pollutants, generating unsafe levels of PM2.5, nitrogen dioxide, carbon monoxide, and formaldehyde. Using a properly sized, exhaust fan ducted to the outside can help, but might not be enough.
Other sources include dust and dust mites, pet dander, mold spores, and bacteria which become airborne with air movement. Building materials, construction, demolition, and normal wear and tear may add lead, paint, and asbestos dust to the indoor environment. Virus particles—ultrafine in size—are perhaps the most dangerous indoor air pollutant, particularly when aerosolized for easy transmission.
Some of the pollutants are brought in through open windows and doors. Among these are tree pollen, carbon monoxide, wildfires, environmental smoke, ultrafine particles from combustion engines in automobiles and manufacturing facilities nearby, and ozone-containing smog; even dust storms or volcanoes a continent away can be a factor. Taking a higher-level view, many types of particle pollution are linked to climate change.
While not considered particulate matter, VOCs (volatile organic chemicals) and invisible gasses such as nitrogen dioxide, formaldehyde, and radon can also contribute to poor indoor air quality and health complications.
Here's the good news: While the potential sources are many, it is unlikely that your home has all of these pollutants or at least all of them at the same time. So rather than feeling daunted by the dangers, take action to reduce or eliminate the known or most likely culprits in your home.
What to do next? What steps can you take to improve your indoor air quality?
Fortunately, there are solutions, many of them easily achieved. Where to begin and which to use depends on which indoor air pollutants are of the most concern.
Read next: Help! How Do I improve my IAQ?