The American Lung Association has released its annual "State of the Air"
report which focuses on levels of air pollution
in U.S. metropolitan areas. The research focuses on the period from 2015 to 2017 and it found that more U.S. cities had high days of ozone and short-term particle pollution compared to 2014-2016 with many areas experiencing higher levels of year-round particle pollution. 43.3 percent of the U.S. population, some 141.1 million Americans, are now exposed to unhealthy air. That represents an increase on the past two reports but despite the spike, it remains far below the 166 million recorded in the 2016 report.
Los Angeles was named the worst U.S. city for ozone pollution, a title it has held for 19 of the past 20 year. Six other cities in California make the top-10 list for ozone pollution. When it comes to year-round particle pollution, Fresno-Madera-Hanford, CA, came first while Bakersfield, CA, remained in first place for short-term particle pollution
. Why are Californian cities ranked so badly despite the Golden State having the strongest environmental regulations in the country? Its growing population and topography are the main reasons with increasing numbers of people resulting in more traffic and higher levels of pollution. Much of the population also live in valleys and basins where air pollution is usually worse.