Think of air pollution as only a problem in other countries? 

“It is true that the footprint of air pollution is smaller in the United States, but there’s no escaping the fact that levels today in North America are still not acceptable,” says Sanjay Rajagopalan, director of the Cardiovascular Research Institute at the Case Western Reserve University School of Medicine.

“If you’re living in an urban environment or in many parts of California, for instance, you may be exposed to persistently high levels of air pollutants.”

Why California? That’s partly due to raging wildfires in the West, which are intensifying because of climate change.

“Pollution levels during forest fires are incredibly high,” says Rajagopalan.

The source of most air pollution: fossil fuels. “The same fossil fuel emissions that drive climate change also drive air pollution,” notes Rajagopalan.

It’s easy to imagine how breathing in polluted air harms people with asthma or other lung problems. Yet the evidence that pollution causes heart attacks or other cardiovascular events is stronger than for lung disease, cancer, or any other illness, says the U.S. Environmental Protection Agency. Here’s how.

The damage

Of the key air pollutants tracked by the EPA, two have an outsized impact on health.

The “ozone layer” in the stratosphere helps keep dangerous ultraviolet radiation from reaching the Earth’s surface. In contrast, “ground-level ozone is produced by photochemical reactions that occur in the presence of sunlight and heat, and it can be very toxic,” says Rajagopalan.

air pollution diagram
Most air pollution comes from burning fossil fuels. Emissions from cars, power plants, oil refineries, factories, etc., can create haze and harm our health.
Environmental Protection Agency.

Even worse: PM2.5—that is, particulate matter (tiny particles and droplets) suspended in the air that measures less than 2.5 microns wide (about 1/30 the width of a human hair).

“Ozone is more important for asthma and lung problems, while particulate matter is disproportionately implicated in cardiovascular events,” says Rajagopalan, who led the panel of experts that wrote the American Heart Association’s advice for protecting yourself from particulate matter.

How does PM2.5 cause trouble? 

“Many people are walking around on the precipice of a heart attack,” notes Rajagopalan. “Air pollution can push you over the cliff.”

It’s not clear how. Among the possibilities: Inhaled particles could lead to inflammation that makes blood more prone to clot. “Or it could destabilize the plaque in your blood vessels,” says Rajagopalan.

PM2.5 may also cause damage over the long term. “Air pollution may elevate blood pressure and accelerate atherosclerosis, the buildup of plaque in blood vessels,” says Rajagopalan.

PM2.5 may also damage the lining of blood vessels and disturb heart rhythm.

Some people are at greater risk than others. “They include people over 65, patients with lung disease, heart disease, diabetes, or chronic kidney disease, and people who have had organ transplants,” notes Rajagopalan.

What to do

Here’s how you can protect yourself, especially if you’re at high risk and live in an area with high pollution levels:

  • Check your AQI. Go to the EPA’s website to find the current AQI (Air Quality Index) for your ZIP code.
  • Consider wearing an N95 mask. The same N95 mask that can protect you from Covid can also help keep out PM2.5.
  • Use your car’s AC. If you spend a lot of time in traffic, keep your windows closed, use air conditioning, and consider getting a high-efficiency cabin filter.
  • Consider an air cleaner. The EPA’s website has advice on portable air cleaners (for a room) or an upgraded HEPA filter for your furnace or central HVAC (heating, ventilation, and air conditioning) system. Avoid electrostatic air cleaners, which ionize particles. They can increase ozone levels.
  • Don’t be afraid to exercise outdoors. “For most healthy people, the benefits of exercise even in a slightly higher polluted environment outweigh the adverse consequences,” says Rajagopalan. (To see if the current air quality in your area is unsafe for exercise, go to
screenshot of
Go to to find your area’s current AQI (Air Quality Index), a Fire and Smoke Map, advice on whether it’s safe to exercise outdoors, and more.

Of course, the smartest solution is to stop polluting our air. And that means burning less fossil fuel. 

“If we turn down the dial on using fossil fuel to generate power and transition to a green economy, it’s going to reduce deaths due to air pollution,” says Rajagopalan.

“What’s good for climate change is good for the environment and health.”