The Clean Air Act is turning 50 this year!
Since 1970, the combined emissions of (criteria and precursor) pollutants have decreased by 77%.
The EPA released an interactive report (using preliminary data from the EPA’s Air Quality System and AirNow.gov) showing changes in air quality and pollution over the first twenty years of the 21st century. According to this report, the number of “unhealthy” air days for sensitive groups in LAs Vegas dropped from 48 in 2018 to 5 in 2019. The ten year average was 31.
You can check out the most recent full EPA report here.