This resource has been factchecked by policy experts, using the latest scientific research. Find all our sources linked below.
99% of the global population breathes air that exceeds WHO safety guidelines
The air we breathe is contaminated by atmosphere-altering pollutants from many sources, including power plants, oil and gas operations, transportation, factories, trash incineration, agriculture, wildfires, fireplaces, and chemicals in everyday household products. In the U.S., more than four in ten people live with unhealthy air quality—outdoors and indoors. The World Health Organization (WHO) estimates that 99% of the global population breathes air that exceeds their own safety guidelines.
This air pollution harms our health in many ways: from irritation of the eyes, nose, and throat to asthma to cancer to death. Pregnant people, babies, children, older adults, and people with underlying health problems are the most vulnerable. Exposure to air pollution before birth may have lifelong impacts.
The climate crisis and air pollution are inextricably linked. Greenhouse gases like carbon dioxide and methane heat the climate, leading to extreme temperatures and wildfires, which, in turn, add more pollution to the atmosphere. It’s a terrible cycle. These days, it’s prudent to check the Air Quality Index (AQI) and plan our days accordingly when it’s unhealthy.
Getting to know outdoor air pollutants
These five key air pollutants monitored by the Air Quality Index, the Environmental Protection Agency’s index for reporting air quality, are regulated by the Clean Air Act. The National Ambient Air Quality Standards (NAAQS) for each of these “criteria air pollutants” also informs the AQI.
Particle pollution—tiny particles in the air from burning fossil fuels for energy, agriculture, wildfire smoke, and transportation. Fine particle pollution is also known as PM2.5 or soot.
Carbon monoxide—of concern in homes, carbon monoxide comes from burning fuel, stoves, and furnaces.
Ground-level ozone—also known as smog, a powerful lung irritant. Extreme heat combines with air pollution to create smog.
Nitrogen dioxide (NO2)—these emissions from burning fossil fuels come from power plants and vehicle exhaust and add to the formation of ground-level ozone.
Sulfur dioxide (SO2)—SO2 also comes from burning fossil fuels, typically from industrial facilities and power plants.
Hazardous air pollutants
In addition to the five criteria air pollutants, EPA regulates 188 hazardous air pollutants. There is no AQI for the super-toxic pollutants on this list. These include potent carcinogens such as dioxins, formaldehyde, ethylene oxide, and benzene, as well as heavy metals like mercury and lead, which are especially dangerous for the brains of developing babies and children. In the U.S., the biggest source of mercury pollution is coal-fired power plants. Lead can also be released by burning coal, as well as from smelters, battery recycling, and mining operations.
Air pollution and health
Air pollution is the fourth-leading cause of death worldwide, responsible for more than 8 million deaths each year. This number has increased over the past two decades. Fossil fuel–derived air pollution alone is responsible for one in five deaths around the world.
Health impacts vary by pollutant, but in general, air pollution can cause heart attacks and cardiovascular damage, stroke, cancer, asthma and other respiratory diseases, adverse birth outcomes including preterm birth, cognitive issues, dementia, and mental health concerns. Air pollution may damage every organ in the human body.
Babies and children, whose lungs are still developing, are extra vulnerable to polluted air.
Indoor air quality (IAQ)
Indoor air can be two to five times more polluted than outdoor air, and people in the U.S. spend 90% of their time inside. Pollutants concentrate in enclosed spaces, and many homes have inadequate ventilation. Immediate and long-term health effects of poor IAQ include respiratory and heart disease, plus cancer. Typical indoor air pollutants can include:
- Cooking, stoves, cigarettes, fireplaces, and candles
- Fumes from attached garages storing cars, motorcycles, or lawn mowers
- Radon, a cancer-causing gas that occurs naturally in some soils
- Household cleaners and “air fresheners,” especially those with synthetic fragrance
- Building and paint products, adhesives, and solvents
- Deteriorating building materials containing asbestos
- Personal care products like perfume and hairspray
- Pesticides, including treatments for cockroaches and fleas
- Fumes emitting from new furniture, carpets, and plastic shower curtains
- Mold from humidity and leaks Wildfire smoke through openings like windows
- Gardening and lawn care products
Environmental justice and air pollution
Communities of color and people experiencing poverty are especially burdened by air pollution. Historically marginalized Black and Latino communities are more likely to be located near oil and gas development, petrochemical production, mining, waste combustion, and other heavily polluting industries. This exposure results in cancers, respiratory ailments, and other health harms. Majority Black, Hispanic, and Indigenous American census tracts also face elevated levels of toxic smoke and particle pollution from wildfires.
Protecting us all from air pollution
Simple steps to reduce indoor air pollution include not smoking, improving ventilation, and decreasing humidity to deter mold growth. When resources allow, individuals can buy safer products that won’t harm indoor air quality, try to adopt cleaner energy, and check the AQI to avoid strenuous exercise on poor air quality days. But ultimately air pollution is too big to tackle alone. Legislation and regulation are required to clean up air pollution. Join Moms Clean Air Force to demand the strongest possible federal and state protections to keep pollution out of our air and protect the health of our families.
Full list of sources.
Updated: June 2024