Air pollution limits in U.S. inadequate to prevent deaths

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Existing air quality rules in the U.S. are not enough to prevent tens of thousands of premature deaths each year, according to a new study published in the New England Journal of Medicine.

Researchers used 12 years of data — health records from more than 60 million Medicare beneficiaries, combined with a massive databank of pollution readings — to link specific air quality levels to death rates.

‘There is not really a safe level of air pollution.’ – Qian Di, Harvard T.H. Chan School of Public Health

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 per cent. 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 per cent, 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 wrote in the NEJM.

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 metre are likely to be even more effective than previous reductions.”

‘Compelling’ evidence

Senior study author Francesca Dominici, a professor of biostatistics at Harvard, told Reuters Health 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 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 per cent thanks to stricter air standards.


Thick smog is trapped in an Alpine, Utah, valley on January 31, 2017, due to a temperature inversion. Severe inversions have plagued Utah’s large cities for many years. (George Frey/Getty Images)

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 kilometre 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.

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.”

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Air pollution limits in U.S. inadequate to prevent deaths

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