Soot exposure boosts virus death rate — study

By Sean Reilly | 04/07/2020 01:14 PM EDT

A new study finds exposure to fine particles is associated with higher death rates from COVID-19.

A new study finds exposure to fine particles is associated with higher death rates from COVID-19. Claudine Hellmuth/E&E News(illustration); CDC(virus); Freepik(man)

This story was updated at 1:55 p.m. EDT.

The new coronavirus causes a sharply higher death toll among patients in areas with even slightly increased levels of a particularly dangerous form of air pollution, Harvard University researchers conclude in a new national study.

"A small increase in long-term exposure" to fine particles "leads to a large increase in [the] COVID-19 death rate," the researchers, based at the university’s T.H. Chan School of Public Health, wrote in the study posted online this week.


Specifically, they linked an increase in fine particle exposure levels of just 1 microgram per cubic meter of air with a 15% higher death rate from COVID-19. For Manhattan, the findings suggest a drop in long-term average exposure by that 1 microgram threshold would have prevented 248 of the approximately 1,900 virus-related deaths reported as of last Saturday, the paper says.

The study covers almost 3,100 counties in the U.S. up to that date; the results "underscore the importance of continuing to enforce existing air pollution regulations to protect human health both during and after the COVID-19 crisis," they write.

They single out EPA’s announcement late last month that it would ease enforcement during the COVID-19 pandemic, saying the policy would allow power plants and other industrial facilities to decide for themselves "if they are able to meet legal requirements on reporting air and water pollution."

Experts at the Chan school and elsewhere had previously predicted loosened enforcement would imperil people with existing respiratory problems (Greenwire, March 20). The new study, however, is the first to examine the nationwide relationship between COVID-19 death rates and fine particle exposure, according to the authors.

In a letter to members of Congress last week, EPA enforcement chief Susan Bodine said that the relaxed enforcement policy will be applied retroactively on a case-by-case basis and that permit holders "are expected to return to compliance as quickly as possible, once the COVID-19 threat subsides."

The disease "is a new and evolving situation and scientists are working hard to understand what variables are linked to transmission and vulnerability," an EPA spokeswoman added in an email today.

The study is now undergoing peer review prior to publication, Francesca Dominici, a biostatistics professor at the Chan school and one of the authors, said in a phone interview this morning. The findings, which were first reported by The New York Times, will be continually updated, she said, because, "unfortunately, more deaths will occur."

Fine particulate matter, often dubbed soot, is technically known as PM2.5 because it is no bigger than 2.5 microns in diameter, or one-thirtieth the width of a human hair.

PM2.5 is already associated with an array of heart and lung problems, including a higher risk of premature death in some circumstances. The connection with the coronavirus’s impact appears to be especially lethal, with a small increase in long-term exposure tied to a jump in the COVID-19 death rate that is 20 times that of "all-cause mortality," the study says.

Under the Clean Air Act, EPA must periodically review and, if needed, revise the ambient air quality standards for PM2.5 based on research on its health and environmental effects. The latest review, which has pitted industry groups against public health and environmental organizations, is in its final stages after an EPA advisory committee rejected the conclusions of agency career staff that a significantly stronger annual standard was needed to prevent thousands of premature deaths each year.

A proposed EPA rule is now undergoing a routine assessment by the White House Office of Information and Regulatory Affairs. Although the contents have not been made public, observers expect it to stick with the status quo of an annual threshold of 12 micrograms per cubic meter of air and a 24-hour standard of 35 micrograms per cubic meter of air. Under a fast-track schedule, EPA plans to issue a rule incorporating its final decision by year’s end.

Advocates on both sides are continuing to press their respective positions with the White House. Yesterday, for example, representatives of the U.S. Chamber of Commerce, the American Petroleum Institute and several other industry trade groups met by teleconference with OIRA and EPA officials to echo the advisory committee’s recommendation in favor of the status quo, Matt Letourneau, a Chamber spokesman, said in an email this morning.

Based on EPA’s latest air trends report, Letourneau said, yearly annual "PM2.5 concentrations have declined by 39 percent since 2000 and 16 percent since 2010 with additional reductions expected in the years ahead."

Late last month, however, advocates of stricter limits also met by phone with EPA and OIRA employees. Among them were representatives of the Union of Concerned Scientists and the Environmental Protection Network, a group opposed to Trump administration environmental policies, according to records posted on a government website. They also included Chris Frey, a North Carolina State University engineering professor who headed the advisory panel known as the Clean Air Scientific Advisory Committee during part of the Obama administration.

Last fall, Frey headed a comparable unofficial panel assembled by the Union of Concerned Scientists that concluded the annual PM2.5 standard should be reduced to somewhere between 8 and 10 micrograms per cubic meter of air, while the 24-hour limit ought to fall within a range between 25 and 30 micrograms. A copy of the unofficial panel’s report was given to OIRA, a part of the White House Office of Management and Budget, the records indicate.

The new Harvard study "provides additional evidence to support a significant strengthening of both the annual and daily standards," Harold Wimmer, president and CEO of the American Lung Association, said in a statement today.