Levels of fine particulate matter have increased in the last two years, with deadly results, while enforcement actions have decreased.
In terms of public health, one of the worst air pollutants is fine particulate matter. From 2009 to 2016, average levels of these particulates in the ambient air in the U.S. plummeted by 24.2 percent. That’s the good news.
The bad news is that from 2016 to 2018, average levels jumped by 5.5 percent.
As a result of that increase, 4,900 Americans died prematurely in 2017, and 9,700 died prematurely in 2018, according to the government’s own estimates of the likely effects of exposure to fine particulate matter.
In short, the air got a lot cleaner during the years when Barack Obama was president (preventing tens of thousands of premature deaths), and has become a lot dirtier under President Donald Trump. 1 But instead of scoring political points or assigning blame, let’s try to understand what is happening, with the help of new research from economists Karen Clay and Nicholas Muller of Carnegie Mellon University.
Reductions in air pollution are among the spectacular success stories in American government. Since 2000, there have been significant decreases in fine particulate matter, technically referred to as PM 2.5, and the progress occurred under President George W. Bush as well as Obama – a 39 percent decline in the national average. Fine particulate matter comes from many sources, including motor vehicles, coal-fired power plants and forest fires. The decreases are attributable, in significant part, to regulatory restrictions.
If you look at other pollutants and longer time frames, you can find even more impressive achievements. For example, ambient concentrations of nitrogen oxide have fallen by 61 percent since 1980, and ambient concentrations of lead have declined by a spectacular 99 percent since that time.
The Clean Air Act, first signed into law by President Richard Nixon in 1970, has almost certainly prevented tens of thousands of deaths — and perhaps as many as 230,000. It has also prevented many thousands of cases of nonfatal heart disease; tens of thousands of emergency-room visits; and as many as two million cases of exacerbated asthma symptoms.