Coal power plants are responsible for half a million deaths nationwide from 1999 to 2020. Coal-fired power plants in Texas caused 27,000 deaths during that period.

Those are among the findings in a new study conducted by six universities, including the University of Texas at Austin.

Ohio and Pennsylvania plants alone, the authors said, caused more than 103,000 deaths nationwide during that period.

The paper, “Mortality risk from United States coal electricity generation,” which was published in “Science,” drew on data from the United States’ 480 coal-fired power plants.

It found that from 1999 to 2000, approximately 460,00 deaths in the Medicare population were attributable to coal electricity-generating emissions.

The study concludes that the small particles in the air from the plants are twice as harmful as previously thought.

There is a bit of good news to be found, however. According to the authors, deaths from coal were the highest in 1999 but decreased by about 95% by 2020 as coal plants installed scrubbers or simply shut down.

“I see this as a success story,” author and UT associate professor Cory Zigler said. “Coal power plants were this major burden that U.S. policies have already significantly reduced. But we haven’t completely eliminated the burden. So, this study provides us a better understanding of how health will continue to improve and lives will be saved if we move further toward a clean energy future.”

The authors noted that deaths from the Keystone power plant in Pennsylvania averaged more than 600 per year prior to the installation of emissions scrubbers, but dropped to below 100 per year after that.

A team member created an online tool that allows the user to visualize deaths from each power plant. The deaths happened nearby and farther away. The tool shows, for example, that Texas power plants caused 27,000 deaths during the study period, and most of them happened outside the state’s borders.

Other states’ power plants caused deaths inside Texas. The authors said that of the 19,600 Texans who died between 1999 and 2020, 10,800 could be attributed to Texas power plants and the remainder were linked to power plants outside of the state.

The authors used public data to track coal pollution and its effects. All of the coal plants that operated in the U.S. between 1999 and 2020 were required to report sulfide dioxide emissions to the Environmental Protection Agency.