15 U.S. Cities with the Biggest Decline in Air Pollution

Los Angeles smoky skyline
J Dennis / Shutterstock.com

This story originally appeared on Filterbuy.

While the recent wildfires in Western states have introduced new concerns about air quality, the U.S. has made huge strides in the reduction of air pollution in recent decades.

As a result of the Clean Air Act and modern pollution control technologies, emissions of common air pollutants have dropped by more than 70% since 1970, according to new data from the Environmental Protection Agency.

These reductions, which the EPA claims have significantly improved the environment and human health, occurred despite a growing population, increased energy use and more cars on American roads.

The EPA measures air quality through the Air Quality Index, or AQI. The AQI rates air quality with values between 0 and 500. An AQI over 100 is considered unhealthy for sensitive groups, and anything over 150 is unhealthy for everyone. Major pollutants accounted for by the AQI and regulated by the Clean Air Act include ground-level ozone, particle pollution (or particulate matter), carbon monoxide, sulfur dioxide, nitrogen dioxide and lead.

Components of air pollution pose dangers to the environment and to overall health. Health effects can include reduced oxygen levels; respiratory symptoms; eye, ear and nose irritation; damage to the nervous system; high blood pressure; and heart disease. Those most at risk from air pollution include unborn babies, children, older adults, and people with asthma, heart, and lung disease.

To determine the metropolitan areas with the largest decreases in air pollution over the past decade, researchers at Filterbuy ranked locations by the percentage change in median AQI between the five-year period ending in 2019 and the five-year period ending in 2009. Five-year periods were used to lessen the effects of annual variability in AQI on the overall results.

Here are the large metropolitan areas with the biggest improvement in air quality over the past decade.

15. Atlanta

Atlanta, Georgia
f11 photo / Shutterstock.com
  • 10-year percentage change in median AQI: -20.8%
  • Median AQI (2015-2019): 53
  • Median AQI (2005-2009): 66
  • Number of good AQI days per year (2015-2019): 158
  • Number of good AQI days per year (2005-2009): 77

14. Kansas City, Missouri

Kansas City, Missouri
Scruggelgreen / Shutterstock.com
  • 10-year percentage change in median AQI: -21.0%
  • Median AQI (2015-2019): 49
  • Median AQI (2005-2009): 62
  • Number of good AQI days per year (2015-2019): 198
  • Number of good AQI days per year (2005-2009): 103

13. New Orleans

New Orleans, Louisiana at night
f11 photography / Shutterstock.com
  • 10-year percentage change in median AQI: -22%
  • Median AQI (2015-2019): 46
  • Median AQI (2005-2009): 59
  • Number of good AQI days per year (2015-2019): 224
  • Number of good AQI days per year (2005-2009): 121

12. Indianapolis

Indianapolis, Indiana
Alexey Stiop / Shutterstock.com
  • 10-year percentage change in median AQI: -22.3%
  • Median AQI (2015-2019): 51
  • Median AQI (2005-2009): 65
  • Number of good AQI days per year (2015-2019): 178
  • Number of good AQI days per year (2005-2009): 81

11. Charlotte, North Carolina

Charlotte, North Carolina
Kevin M. McCarthy / Shutterstock.com
  • 10-year percentage change in median AQI: -22.5%
  • Median AQI (2015-2019): 47
  • Median AQI (2005-2009): 61
  • Number of good AQI days per year (2015-2019): 212
  • Number of good AQI days per year (2005-2009): 115

10. Virginia Beach, Virginia

Virginia Beach, Virginia
JoMo333 / Shutterstock.com
  • 10-year percentage change in median AQI: -22.9%
  • Median AQI (2015-2019): 38
  • Median AQI (2005-2009): 50
  • Number of good AQI days per year (2015-2019): 310
  • Number of good AQI days per year (2005-2009): 187

9. Tampa, Florida

Tampa, Florida
kevin-j-king / Shutterstock.com
  • 10-year percentage change in median AQI: -23.4%
  • Median AQI (2015-2019): 44
  • Median AQI (2005-2009): 57
  • Number of good AQI days per year (2015-2019): 250
  • Number of good AQI days per year (2005-2009): 128

8. Chicago

Chicago with clouds
Sean Pavone / Shutterstock.com
  • 10-year percentage change in median AQI: -24.2%
  • Median AQI (2015-2019): 55
  • Median AQI (2005-2009): 73
  • Number of good AQI days per year (2015-2019): 132
  • Number of good AQI days per year (2005-2009): 36

7. Memphis, Tennessee

Memphis, Tennessee
f11photo / Shutterstock.com
  • 10-year percentage change in median AQI: -25.6%
  • Median AQI (2015-2019): 44
  • Median AQI (2005-2009): 59
  • Number of good AQI days per year (2015-2019): 242
  • Number of good AQI days per year (2005-2009): 120

6. Cleveland

Cleveland, Ohio
Rudy Balasko / Shutterstock.com
  • 10-year percentage change in median AQI: -25.7%
  • Median AQI (2015-2019): 50
  • Median AQI (2005-2009): 67
  • Number of good AQI days per year (2015-2019): 185
  • Number of good AQI days per year (2005-2009): 109

5. Phoenix

Phoenix, Arizona
Anton Foltin / Shutterstock.com
  • 10-year percentage change in median AQI: -26.8%
  • Median AQI (2015-2019): 76
  • Median AQI (2005-2009): 104
  • Number of good AQI days per year (2015-2019): 40
  • Number of good AQI days per year (2005-2009): 30

4. Pittsburgh

Pittsburgh
esb-professional / Shutterstock.com
  • 10-year percentage change in median AQI: -26.8%
  • Median AQI (2015-2019): 57
  • Median AQI (2005-2009): 78
  • Number of good AQI days per year (2015-2019): 119
  • Number of good AQI days per year (2005-2009): 39

3. Birmingham, Alabama

Birmingham, Alabama
Sean Pavone / Shutterstock.com
  • 10-year percentage change in median AQI: -27.2%
  • Median AQI (2015-2019): 51
  • Median AQI (2005-2009): 71
  • Number of good AQI days per year (2015-2019): 169
  • Number of good AQI days per year (2005-2009): 54

2. Louisville, Kentucky

Louisville, Kentucky
f11photo / Shutterstock.com
  • 10-year percentage change in median AQI: -27.4%
  • Median AQI (2015-2019): 49
  • Median AQI (2005-2009): 67
  • Number of good AQI days per year (2015-2019): 198
  • Number of good AQI days per year (2005-2009): 75

1. St. Louis

St. Louis
CrackerClips Stock Media / Shutterstock.com
  • 10-year percentage change in median AQI: -36.5%
  • Median AQI (2015-2019): 53
  • Median AQI (2005-2009): 84
  • Number of good AQI days per year (2015-2019): 154
  • Number of good AQI days per year (2005-2009): 36

Disclosure: The information you read here is always objective. However, we sometimes receive compensation when you click links within our stories.

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