Across the United States, about 134 million people are at risk from air pollution
, according to the American Lung Association's 19th annual air quality report
. It found that while ozone pollution has worsened due to warmer temperatures, there was an improvement in particle pollution between 2014 and 2016. Despite that, more than four in 10 Americans live in yountries with unhealthy air pollution levels that can cause premature death through a number of health conditions such as lung cancer or cardiovascular damage.
Despite pouring money into cutting back on emissions, California still has the distinction of having some of the most polluted metropolitan regions
in the nation. The report found that six out of the top-10 metros with the worst year-round concentration of particular matter are located in California, with Bakersfield quite notable. It ranked as worst, second and third worst in the three categoies of air quality measured in the report. That's due to emissions from agriculture, industry, rail freight and traffic congestion mixing to make its air harmful.
Even though Alaska is generally viewed as something of an unspoiled wilderness, it's actually home to the worst metro for annual PM 2.5 pollution: Fairbanks. The primary reason it comes first is due to indoor pollution from people using wood-burning stoves and other wood-buring heaters to keep themselves warm in the state's harsh winters. The metros with the cleanest air in the country are Albany, Schenectady (NY), Urban Honolulu (HI) and Casper (WY).