Air pollution worsened in the United States in 2017 and 2018, new data shows, a reversal after years of sustained improvement with significant implications for public health.
In 2018 alone, eroding air quality was linked to nearly 10,000 additional deaths in the US relative to the 2016 benchmark, the year in which small-particle pollution reached a two-decade low, according to researchers at Carnegie Mellon University.
The study focuses on fine-particle air pollution, known as PM2.5, which is of particular concern to regulators and public health experts because its microscopic size means it can be inhaled and absorbed into the bloodstream.
Its ill effects are only now starting to be fully understood – the Environmental Protection Agency (EPA) didn’t even have a regulatory standard for it until 1997.
Fine particles can damage a person’s respiratory system, accumulate in the brain and send people to the emergency room. The elderly appear to be especially susceptible to PM2.5, which has been linked to dementia and cognitive decline.
And the data shows that many of the pollutant’s effects occur at levels well below current regulatory thresholds.
Overall, concentrations of the pollutant have risen about 5.5 percent since 2016, and the Carnegie Mellon researchers identified several reasons for this, including rising natural gas use and people doing more driving.
The corresponding rise in emissions from those sources more than offsets the falling levels being realized by the decline in coal being burned by electricity-generating plants in the United States.
An increase in wildfires is another factor because they release large amounts of smoke and fine particles into the atmosphere. Big fires, particularly in California in 2018, played a role in driving up total national air pollution.
Removing those fires from the analysis lessens the increase in pollution in 2017 and 2018 but doesn’t eliminate it, the researchers write.