Report: U.S. Air Pollution Is Getting Worse

A report by Carnegie Mellon University reveals a 24% drop in fine particulate matter from 2009 to 2016, but a 5.5% increase since then, leading to 10,000 premature deaths in 2018. Factors include economic activity, natural gas use, increased driving, and wildfires, particularly in California. A decline in Clean Air Act enforcement since 2013 is noted, with no increase in actions despite worsening pollution in 2017-2018. Researchers call for better data to understand air quality changes.

What is the size comparison of fine particulate matter to a human hair?

What role did the Clean Air Act enforcement actions play in air quality according to the study?