Four in 10 Americans Are Breathing Unhealthy Air. Are You? (Photo: Getty Images)

Air pollution has been linked to a host of health issues, from stroke to low birth weight, according to recent studies. And in the American Lung Association’s State of the Air 2015 report, roughly four in 10 U.S. residents live in counties where the ozone or particle pollution has reached to unhealthy levels — news that may affect more than 138.5 million.

The new report measures both areas of high particle pollution and high ozone pollution. Tiny particle pollution carries risks like premature death, asthma attacks and lung cancer. Ozone pollution near ground levels bumps risk of hospital visits, wheezing and coughing, asthma issues, heart attacks and even untimely death.

It’s not all bad news. Many cities have seen notable improvements, especially the eastern half of the U.S. — a region that’s made air quality a priority with cleaner power plants and diesel fleets. Thirteen of the 25 metropolitan areas with the worst year-round particle pollution levels earned a “best year yet” badge, including Indianapolis and Birmingham, AL.

On the flip side, the American Lung Association report says that climate change is a factor in the rising risk of air pollution on human health — especially out west, where high temperatures and drought create the perfect conditions for particle pollution. Western areas, like San Francisco and Visalia in California, have seen a record number of days where those pollution levels were highest.

In terms of ozone pollution, the West also saw jumps in the average number of high-pollution days — and overall, ozone improvement (or lack thereof) was mixed. Across the nation, 12 of the worst areas saw an increase in the number of high-pollution days, whereas 13 saw a drop.

In a press release, National President and CEO of the American Lung Association Harold P. Wimmer says all Americans deserve to breathe clean air, but we need to be especially careful of high-risk individuals like infants, children, the elderly, those with lung and heart conditions, those with diabetes, those living in low-income areas and outdoor workers.

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Related: The Troubling Link Between Pollution And Suicide

“One challenge is that many more people are actually at risk than even our estimates show. We use the current ozone standard as the basis of much of our assessment, but that standard is weak, and out of date and does not reflect what we know harms children and people with lung disease,”Wimmer says. “We urge the U.S. Environmental Protection Agency to update the ozone standard to reflect current science and give parents accurate information about the air pollution risks in their community. A standard set at 60 parts per billion would provide much more accurate information and better health protection.”

Currently, the EPA ozone standard is 75 parts per billion. For the complete report and data on each city, check out www.StateOfTheAir.org, and see a few of the American Lung Association’s top 10 lists for cleanest and most polluted cities below.

Nation’s Most Polluted Cities

Top 10 U.S. Cities Most Polluted by Short-term Particle Pollution (24-hour PM 2.5 )

1. Fresno-Madera, Calif.

2. Bakersfield, Calif.

3. Visalia-Porterville-Hanford, Calif.

4. Modesto-Merced, Calif.

5. Los Angeles-Long Beach, Calif.

6. San Jose-San Francisco-Oakland, Calif.

7. Salt Lake City-Provo-Orem, Utah

8. Logan, UT-ID

9. Fairbanks, Alaska

10. Pittsburgh-New Castle-Weirton, Penn.-Ohio-West Va.

Top 10 U.S. Cities Most Polluted by Year-Round Particle Pollution (Annual PM 2.5 )

1. Fresno-Madera, Calif.

2. Bakersfield, Calif.

3. Visalia-Porterville-Hanford, Calif.

4. Modesto-Merced, Calif.

5. Los Angeles-Long Beach, Calif.

6. El Centro, Calif.

7. San Jose-San Francisco-Oakland, CA

8. Cincinnati-Wilmington-Maysville, OH-KY-IN

9. Pittsburgh-New Castle-Weirton, Penn.-Ohio-W.Va.

10. Cleveland-Akron-Canton, OH

Top 10 Most Ozone-Polluted Cities

1. Los Angeles-Long Beach, Calif.

2. Visalia-Porterville-Hanford, Calif.

3. Bakersfield, Calif.

4. Fresno-Madera, Calif.

5. Sacramento-Roseville, Calif.

6. Houston-The Woodlands, Texas

7. Dallas-Fort Worth, Texas-Okla.

8. Modesto-Merced, Calif.

9. Las Vegas-Henderson, Nev.-Ariz.

10. Phoenix-Mesa-Scottsdale, Ariz.

Nation’s Cleanest Cities

Top 10 Cleanest U.S. Cities for Year-round Particle Pollution

1. Prescott, AZ

2. Farmington, NM

3. Cheyenne, WY

3. Casper, WY

5. Flagstaff, AZ

6. Duluth, MN-WI

6. Salinas, CA

6. Palm Bay-Melbourne-Titusville, FL

6. Kahului-Wailuku-Lahaina, HI

10. Rapid City-Spearfish, SD

10. Anchorage, AK

10. Bismarck, ND

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