(Reuters Health) - With the Trump Administration threatening to loosen air pollution controls, a new study is showing that even existing rules are causing tens of thousands of extra deaths in the United States each year.

A truck engine is tested for pollution exiting its exhaust pipe as California Air Resources field representatives (unseen) work a checkpoint set up to inspect heavy-duty trucks traveling near the Mexican-U.S. border in Otay Mesa, California September 10, 2013. REUTERS/Mike Blake

Researchers used 12 years of data - health records from nearly 61 million Medicare beneficiaries, combined with a massive databank of pollution readings - to link specific air quality levels to death rates.

They found that for every increase of just 10 micrograms in small-particle pollution known as PM2.5, the death rate went up 7.3 percent. That’s the equivalent of 120,000 fatalities among people age 65 and older, lead author Qian Di of the Harvard T.H. Chan School of Public Health in Boston told Reuters Health in a telephone interview.

For every 10 part-per-billion rise in ozone concentration, the mortality rate rose by 1.1 percent, producing an extra 19,000 deaths just among the elderly.

Even in years when the concentrations in a region were low, “we continued to see significant associations between exposure and mortality,” Di and his colleagues write in the New England Journal of Medicine.

Their conclusion: current U.S. rules are not strict enough to prevent pollution-related deaths and further reductions in pollution will produce a big drop in fatalities.

“It is clear from this study that there is not really a safe level of air pollution,” said Dr. Brian W. Christman, vice chair of the department of medicine at Vanderbilt University Medical Center in Nashville, Tennessee, who was not involved in the research.

“The Clean Air Act and the Environmental Protection Agency have done great work, but the data indicates that additional effort to reduce PM2.5 and ozone would save lives,” Christman, who is also a spokesman for the American Lung Association, told Reuters Health by phone. “As a matter of fact, further reduction in PM2.5 below the (federal standard) of 12 micrograms per cubic meter are likely to be even more effective than previous reductions.”

Senior study author Francesca Dominici, a professor of biostatistics at Harvard, told Reuters Health in a telephone interview that she hoped the findings “will change the course of recent discussions about dismantling EPA and EPA research and leaving the Paris agreement” designed to slow global climate change by reducing pollution levels.

“The evidence we’re seeing here is very compelling,” she said.

The results come at a time when the Trump administration has begun “to dismantle guidelines intended to reduce emissions from coal-fired electricity plants” and may revoke the waiver that allowed California to adopt stricter vehicle emission standards, according to an editorial accompanying the study.

“Revoking this waiver could have the effect of exposing more than 100 million Americans to higher levels of automobile emissions,” the Journal warns. “Trump’s proposed budget includes crippling cuts to the EPA, including cuts in funding for both federal and state enforcement of regulations. The increased air pollution that would result from loosening current restrictions would have devastating effects on public health.”

The particles studied are dangerous because their tiny size - only visible with an electron microscope - allows them to get deep into the lungs to do damage, and from there they can also enter the bloodstream. According to the Environmental Protection Agency, from 2000 to 2015 the average concentration of PM 2.5 pollution nationally has declined by 37 percent thanks to stricter air standards.

According to the new study, the two regions that saw the greatest improvements in air quality were the central and southeastern United States.

Satellite and weather data, computer models and data from 1,928 particle monitoring stations and 1,877 ozone modeling stations were used to estimate exposure over each square kilometer of the country.

The task was so massive the number crunching had to be done by supercomputer over Harvard’s Christmas break, Di noted.

Because the database was so large, Di and his colleagues were also able to determine that subgroups, including men, blacks, Asians, Hispanics and people eligible for the Medicaid health plan for the poor faced the highest risk from small particle pollution.

It shows “this is not just a health issue, but a social equality issue as well,” said Di, a doctoral student in Harvard’s department of environmental health.

SOURCE: bit.ly/2sPKef2 New England Journal of Medicine, online June 28, 2017.