California has some of the most comprehensive air pollution prevention measures in the US and although cities like Los Angeles are still infamous for their smog, a new report shows that the state’s policies have been highly effective at improving air quality. 

Researchers from the University of California, Berkeley looked at diesel particulate matter emissions from 1990 to 2014 as an indicator of relative air pollution levels in California and the rest of the US. The 24-year period saw a 78 percent diesel particulate matter emissions reduction in California compared to just 51 percent in the country as a whole. Deaths from heart and lung disease linked to diesel pollution also fell by 82 percent statewide.

As the largest state, California still has the most vehicles on the road, but this study shows that air pollution prevention measures are effective in protecting air quality and public health. Over the past 30 years, the state has tightened regulations on diesel engines, initiated the transition to electric ships, and transitioned to a lower-sulfur form of diesel fuel which emits less fine particulate matter than traditional diesel. 

Despite this progress, the report does note that California still has room for improvement. They emphasize that the agricultural industry has struggled to lower emissions even though they account for 18 percent of the state’s diesel pollution. We are excited to see how California continues to progress on its air quality journey, especially as the state is set to discontinue the sale of new combustion engine vehicles by 2035.