Buzz
Honolulu, Hawaii's picturesque downtown boasts the finest air quality among cities worldwide with a similar population size. Art Wager/Getty Images.Air pollution arises when invisible gases like ozone and carbon monoxide mix with minute solid or liquid particles. This results in the hazy effect you often observe drifting above the cityscape on hot summer days.
Ozone pollution results from gases such as those emitted by vehicle exhausts and factory smokestacks. These pollutants can cause respiratory issues, including asthma. Fine particulate pollution mainly comes from vehicles, industrial operations, power plants, and agriculture. Some particles are so minuscule that they can bypass the body's natural defenses and enter the bloodstream. Over time, prolonged exposure to particulate pollution can increase the risk of heart disease, respiratory conditions, and even lung cancer.
Since the passing of the Clean Air Act over 45 years ago, air quality has improved, despite the challenges of climate change. However, many cities still experience poor air quality on certain days, with ozone or particulate matter levels exceeding the limits established by the U.S. Environmental Protection Agency (EPA).
There are some positive exceptions. The American Lung Association's "State of the Air" report evaluates U.S. metro areas using EPA pollution data alongside various other criteria. The report identifies several cities that did not experience any bad air days from 2014 to 2016, including:
- Casper, Wyoming
- Burlington-South Burlington, Vermont
- Wilmington, North Carolina
- Elmira-Corning, New York
- Colorado Springs, Colorado
Some cities experience lower levels of one pollutant but higher levels of another. Fairbanks, Alaska is a prime example — it performs well in terms of lower ozone levels, but it suffers from significant particle pollution due to long winters and the widespread use of wood-burning stoves.
Here are the top five major cities globally with the cleanest air:
- Honolulu, Hawaii
- Halifax, Canada
- Anchorage, Alaska
- Auckland, New Zealand
- Brisbane, Australia
No matter where they are situated, the cleanest cities share a few key characteristics. These cities encourage walking and biking, favor the use of electric cars over traditional vehicles, boast excellent public transportation networks, and feature pedestrian-only areas in their downtowns. Additionally, many of these cities harness solar or wind energy for their power needs.
China's air pollution is so severe that it's visible from space. NASA's Terra satellite captured images showing the dense, gray haze extending 750 miles (1,207 kilometers) from Beijing to Shanghai.
