The researchers looked at a fine particulate matter known as PM2.5. They concluded that the particle decreased in the air by 24.2% from 2009 to 2016, but has increased by 5.5% since 2016.
"The health implications of this increase are significant," Clay said in a statment.
Clay and co-author Nicholas Muller both work at Carnegie Mellon University. They found that the increase in PM2.5 in the air can be particularly harmful to elderly people, who accounted for 80% of the deaths from 2016 to 2018. The other 20% percent of deaths were among adults ages 30 to 64.
The study showed that the rise in air pollution was most prominent in the Midwest and Western regions of the United States, where a number of wildfires occurred in the last couple years.
The data was based on a Air Quality System database and daily monitor readings provided by the Environmental Protection Agency. The study examined 653 counties nationwide for the fine particulate matter and also examined vital statistics in the counties.
The researchers called upon elected officials to monitor pollution levels and noted that enforcement of vital parts of the Clean Air Act have been consistently falling since 2009.
"These increases are worrisome and should persuade policymakers to take the necessary steps to maintain limits on air pollution," Muller said.