How Does Your State’s Air Quality Stack Up?

According to the U.S. Environmental Protection Agency’s AirNow data metrics, the total number of days that were deemed “unhealthy” to “hazardous” on the Air Quality Index has declined from 2000 to 2018. Within the 35 metropolitan areas that were monitored for ozone pollution, the total number of poor air days dropped from 1562 days in 2000 to 671 days in 2018.

Overall, experts use data to show that our air quality has improved despite population and climate change.

Cleanest Air By State

As polluted as we think some of the major metros are, city pollution doesn’t necessarily determine a whole state’s air quality. You may be surprised to see where states rank for best to worst air quality. Here’s our full list of U.S. states in order from cleanest to poorest overall:

  1. Maine
  2. Massachusetts
  3. Hawaii
  4. New York
  5. New Hampshire
  6. Delaware
  7. North Dakota
  8. Maryland
  9. Virginia
  10. Vermont
  11. Idaho
  12. Wyoming
  13. Montana
  14. Minnesota
  15. Connecticut
  16. New Mexico
  17. Georgia
  18. North Carolina
  19. Iowa
  20. Utah
  21. Wisconsin
  22. Rhode Island
  23. South Carolina
  24. Alaska
  25. Nevada
  26. Kansas
  27. Indiana
  28. Washington
  29. Ohio
  30. Mississippi
  31. Illinois
  32. West Virginia
  33. New Jersey
  34. Nebraska
  35. Alabama
  36. Arkansas
  37. Pennsylvania
  38. Michigan
  39. Tennessee
  40. Colorado
  41. Arizona
  42. Florida
  43. Oklahoma
  44. Missouri
  45. Oregon
  46. Louisiana
  47. South Dakota
  48. Kentucky
  49. California
  50. Texas

While you can control the air you breathe indoors with air filters, purifiers, air cleansing plants, and more, you’re not nearly as in control of the air you breathe outdoors. We compared air quality on a state level to see where people breathe easiest and where we may be inhaling dangerous particle pollutants, invisible to the human eye.

Measuring Air Quality

Luckily, the Air Quality System (AQS) compiles air pollution data collected by the U.S. Environmental Protection Agency, state, and local agencies. Along with other publicly accessible databases, we were able to rank each state for the following metrics:

  • Carbon Dioxide Emissions - We compared a dataset from 2005 to 2016 and looked at the percent change in state energy-related carbon dioxide emissions by year. The state with the highest negative percentage change meant that they made progress on limiting their detrimental contributions to ozone.
  • Cigarette Usage Among Adults – The CDC, or Centers for Disease Control and Prevention gathered data using sample sizes in 2017 to gain insight into the percentage of adults who smoke in each state. The higher the percentage, the lower we ranked that state.
  • Air Pollution – Using America’s Health Rankings through the United Health Foundation we looked at 2019 data that looked at the average exposure to particulate matter of 2.5 microns or less. The lower the value, the less pollution, and the higher each state ranked.
  • Air Quality Index – Using the Air Quality Index we gathered air quality health index rankings by cities to find which states had the most and least days categorized as low or high health risks.
  • Rate of Lung Cancer Cases – The CDC also provides data on lung cancer. By averaging new lung cancer cases, rate of lung cancer deaths, and number of lung cancer deaths by state, we ranked states from lowest to highest averages. The lower the average, the less impact lung cancer had on that population, therefore the state ranked higher.

These different metrics don’t all contribute to the quality of air evenly. We re-balanced the data by placing a larger emphasis on pollution, weighting this data at 80%. Correlating metrics such as cigarette usage and lung cancer data was weighted 20%.

Want to know what states had the highest number of lung cancer cases or which states had the highest carbon dioxide emissions? Any states that tied for number of good or poor air days ended up with the same rank, which is why you’ll see repeated numbers in those columns. See where your state stood for each metric below.

State Ranking for Least Cigarette Usage Among Adults Ranking for Smallest Lung Cancer Rates Ranking for Reducing Emissions over 10 years Rank for Air Pollution Rank for Good & Moderate Air Days Rank for Poor Air Days
Maine 28 39 3 7 4 4
Massachusetts 6 13 7 9 12 16
Hawaii 4 2 17 6 35 1
New York 9 24 12 11 7 30
New Hampshire 17 27 1 1 44 1
Delaware 24 8 14 40 3 1
North Dakota 33 49 45 2 5 13
Maryland 8 3 2 30 8 36
Virginia 23 22 18 17 29 5
Vermont 19 14 31 4 39 1
Idaho 10 26 51 15 23 1
Wyoming 35 11 42 3 25 11
Montana 26 9 30 11 28 16
Minnesota 11 4 34 11 37 5
Connecticut 3 7 9 22 40 28
New Mexico 31 37 19 8 30 32
Georgia 30 32 6 40 14 23
North Carolina 27 18 13 22 19 20
Iowa 25 42 39 19 13 9
Utah 1 36 27 43 2 34
Wisconsin 20 23 33 15 27 15
Rhode Island 13 12 29 24 11 19
South Carolina 36 43 23 25 20 19
Alaska 42 48 4 10 42 35
Nevada 32 31 5 46 34 10
Kansas 29 25 28 18 46 7
Indiana 44 47 10 43 15 14
Washington 5 35 46 34 24 12
Ohio 43 50 8 45 17 22
Mississippi 45 21 47 30 9 3
Illinois 15 46 24 48 16 25
West Virginia 50 28 25 29 21 11
New Jersey 7 34 26 36 36 26
Nebraska 14 38 49 19 51 1
Alabama 41 16 16 36 38 6
Arkansas 46 45 44 19 31 2
Pennsylvania 34 51 11 47 22 29
Michigan 37 20 15 34 45 10
Colorado 12 41 20 14 49 31
Tennessee 47 33 40 25 26 24
Arizona 16 19 36 49 6 39
Florida 21 15 35 25 41 17
Oklahoma 39 44 37 39 10 18
Missouri 40 1 22 28 43 16
Oregon 22 40 38 32 50 8
Louisiana 48 17 43 33 18 21
South Dakota 38 29 50 4 47 27
Kentucky 49 30 21 36 48 1
California 2 10 41 50 32 37
Texas 18 5 48 40 33 33