Burning fossil fuels kills an estimated 350,000 Americans a year, including 7,600 in Massachusetts, study finds

In May 2019, smog blanketed the Mexico City skyline. Schools and universities were closed for days because of the pollution, brought on by brush fires and a lack of rain.Marco Ugarte/Associated Press

Nearly 9 million people a year are dying as a result of the burning of fossil fuels, a study has found, roughly twice the previous estimate by the World Health Organization.

In the United States, ingesting the fine particulate matter produced by burning fossil fuels kills an estimated 350,000 people a year, including more than 7,600 people in Massachusetts, according to the study by researchers at Harvard and other universities.

Researchers linked the pollution to 18 percent of worldwide deaths in 2018, down from 21 percent in 2012. They attributed the decline to improved air-quality policies in China that reduced the use of fossil fuels by more than 40 percent.

The authors of the study, published by the journal Environmental Research, said the findings suggested policy makers should be accelerating efforts to eliminate the use of fossil fuels in vehicles and power plants, regardless of their impact on warming the planet. They also said those changes are even more urgent in a world ravaged by a pandemic that attacks the lungs.

“There’s a perception in the United States that we have this under control, but that’s a mistake,” said Joel Schwartz, a professor of environmental epidemiology at Harvard’s T.H. Chan School of Public Health and one of the study’s authors. “We need to work much harder to get the concentrations of particulate pollution down.”

The study found that regions with the highest concentrations of pollution from fossil fuels — Eastern North America, Europe, and Southeast Asia — also had the highest mortality rates.

The World Health Organization’s Global Burden of Disease report, the most comprehensive study on the causes of global mortality, has estimated that 4.2 million people die every year from all airborne particulate matter, which includes smoke from wildfires and agricultural burns, which use fire to manage vegetation.

Previous research has relied on satellite and surface observations to estimate concentrations of particulate matter, but those studies couldn’t distinguish which particles came from fossil fuel emissions and which came from other sources, the scientists said.

To do so, they used computer models of atmospheric chemistry to estimate the impact of fossil fuels, which they sought to validate using surface, aircraft, and satellite observations, they said.

“We wanted to map where the pollution is, and where people live, so we could know more exactly what people are breathing,” said Karn Vohra, a graduate student at University of Birmingham and another author of the study.

Officials at the American Petroleum Institute, which represents producers and distributors of oil and gas, said they have been focused on promoting the transition to natural gas, which they said has helped reduce concentrations of particulate matter by 39 percent since 2000.

“We are committed to building on this progress and protecting public health through industry action, cleaner fuels and emissions reductions, all while safely providing the energy that modern life depends on,” said Bethany Aronhalt, a spokeswoman for the institute.

Tom Kiley, president of the Northeast Gas Association, a trade group representing utilities, noted that the study focused mainly on the impacts of coal, petrol, and diesel, but declined to comment further.

In New England, the main sources of fine particulate matter, also known as soot, are cars and trucks, especially those using diesel engines; coal and oil-burning boilers; wildfires; woodstoves; dust from roads and construction; agricultural operations; and cooking, according to the Environmental Protection Agency. Other sources are power plants and industrial processes such as oil refining and paper production.

The scientists estimated more than 16,500 people are dying per year in New England as a result of fossil fuel pollution, with Massachusetts suffering the highest death toll. Connecticut, with an estimated 4,749 deaths, had the highest per capita rate of mortalities.

While the dangers of particulate pollution have been well known, few studies have linked the dangers to specific sources such as fossil fuels, the authors said.

“Tying the massive [death] toll to fossil fuel is important,” said Doug Brugge, a professor of public health at the University of Connecticut who was not involved in the study. “It has largely been assumed, but critical to tie down.”

Brugge said the study also highlights concerns about the impact of low levels of pollution. His own research has found that people who lived near Interstate 93 and the Massachusetts Turnpike have an increased chance of suffering a heart attack or stroke.

“Most recently, we demonstrated that reducing ultrafine particles in rooms next to highways had a positive effect on blood pressure of people spending time in the rooms,” he said. “Thus, the health impact of fossil fuel pollution could be even higher than reported by the Harvard study.”

The study found a higher death rate for long-term exposure to fossil fuel emissions, even at lower concentrations.

Eloise Marais, an associate professor of physical geography at University College London, said the study suggests policy makers must do more than eliminate the sale of fossil fuel vehicles, which Massachusetts plans to do in 2035. They need to remove millions of existing vehicles from the roads as soon as possible, she said.

“The timelines for these changes need to come sooner,” said Marais, a coauthor of the study. “There needs to be greater urgency to use cleaner forms of energy.”