Two separate studies show that exercising outdoors can increase your chances of dying from the coronavirus. On Tuesday, the American Lung Association issued its annual State of the Air Report that says almost half of the nation’s population is surrounded by polluted air. That’s about 150 million people, almost 9 million more compared to the 2019 figures.

The second study published recently by Harvard University says that COVID-19 patients living in places with high levels of air pollution are at increased risk of dying from the disease. The researchers found that even a small increase in exposure to air tainted with particles from vehicle exhausts, wildfires and coal-fired power plants led to a large increase in the COVID-19 death rate according to TODAY.

“That is a very troubling finding because in our report we show that millions and millions of people live in areas with unhealthy levels of particle pollution,” Paul Billings, national senior vice president of public policy at the American Lung Association, told Today.

And with gyms closed, and more and more Americans are taking their exercise routines to the streets, Billings says that other health hazards can result.

“We do know that elevated levels of pollution are linked to a wide range of adverse health impacts—coughing, wheezing and shortness of breath,” he noted.

The most polluted cities in America,according to the State of the Air report include:

• Los Angeles-Long Beach, CA
• Bakersfield, CA
• Visalia, CA
• Phoenix-Mesa, AZ
• Las Vegas-Henderson, NV

The cleanest cities all round with zero ozone or year-round particle pollution are:

• Bangor, ME
• Burlington-South Burlington, VT
• Urban Honolulu, HI
• Wilmington, NC

The American Lung Association offers these tips for outdoor activity:

• Don’t exercise or run near busy intersections. It’s best to avoid any pollution from cars.
• Exercise outdoors early in the morning before traffic and pollution rises.
• Monitor the air quality in your community by checking AirNow.gov before heading out.