Deaths linked to coal exhaust have dropped but coal exhaust is twice is likely to contribute to deaths as other air pollution, a new study found.Coal, the dirtiest of fossil fuels, is far more harmful to human health than previously thought, according to a new report, which found that coal emissions are associated with double the mortality risk compared with fine airborne particles from other sources.The research, published Thursday in the journal Science, linked coal pollution to 460,000 deaths among Medicare recipients aged 65 and older between 1999 and 2020.Yet the study also found that during that period the shuttering of coal plants in the United State, coupled with the installation of scrubbers in the smokestacks to “clean” coal exhaust, has had salubrious effects. Deaths attributable to coal plant emissions among Medicare recipients dropped from about 50,000 a year in 1999 to 1,600 in 2020, a decrease of more than 95 percent, the researchers found.“Things were bad, it was terrible,” Lucas Henneman, the study’s lead author, and an assistant professor in environmental engineering at George Mason University, said in an interview. “We made progress, and that’s really good.”Researchers from six universities collected emissions data from 480 coal power plants between 1999 and 2020. They used atmospheric modeling to track how sulfur dioxide converted into particulate matter and where it was carried by wind, and then examined millions of Medicare patient deaths by ZIP code.Though the researchers could not identify exact causes of death, the statistical model showed that areas with more airborne coal particulates had higher death rates.Some 138 coal plants each contributed to at least 1,000 excess deaths, and 10 plants were linked to more than 5,000 deaths apiece, the researchers found.While fine particulate matter, known as P.M. 2.5, is frequently examined for its health risks, the researchers found that inhaling those fine particles from coal exhaust was especially deadly.Breathing in coal exhaust was associated with more than double the mortality risk compared with inhaling fine particulates from other sources, the researchers determined.They also published an online tool showing deaths attributed to individual coal-fired power plants.“We can’t say how long these people would’ve lived without exposure,” Dr. Henneman said. “But we are saying they died earlier than they otherwise would have because of this coal pollution.”Requirements that coal-fired power plants “scrub” the pollutants they emit, by removing sulfur dioxide using a cloud of water droplets, proved a game changer for public health.After scrubbers were installed in 2009 and 2010 at the Keystone power plant in Pennsylvania, the average number of annual deaths linked to the plant dropped to 80 from 640, the researchers found. They also found that the average level of coal P.M. 2.5 across the United States dropped to 0.07 micrograms in 2020 from 2.34 micrograms per cubic meter of air in 1999.“People today are living longer without as much of this coal pollution in the air,” Dr. Henneman said. “It’s this major success story.” Coal use is declining in the United States, but is increasing worldwide. It is projected to peak in 2025, at which point renewable energy sources are forecast to become the largest source of electricity production.The new study in Science adds to mounting evidence of the health benefits that come from moving away from the burning of fossil fuels, especially for vulnerable populations.In California, the addition of 20 zero emission vehicles for every 1,000 people in a given ZIP code correlated to a 3.2 percent drop in the rate of asthma-related emergency room visits, according to a study published earlier this year in the journal Science of the Total Environment.In Chicago, the closure of three coal-fired plants was followed by a 12 percent decrease in asthma-related emergency room visits for children aged 4 and under living in the area relative to rates in places farther away, according to research published in 2021 in the American Journal of Public Health.And after a large coal-processing plant shut down in Pittsburgh in 2016, there was an immediate 42 percent drop in weekly hospital visits for heart-related problems for nearby residents, another study found. The health benefits continued, with 33 fewer hospitalizations for heart disease on average for each of the three years after the plant’s closure compared with the three years before.In May, the Environmental Protection Agency proposed new rules that would cap the amount of pollutants that power plants could pump out, and estimated there’d be up to $85 billion in climate and health benefits. But given how deadly coal particulates have been found to be, Dr. Hennemen said the benefits would likely be far greater. Stronger curbs on tiny airborne particles could also result in a 7 percent drop in death rates for Black and low-income older people who have long been subjected to the country’s most polluted air, according to research published earlier this year.