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 The study, published in Nature, is the first to calculate how
pollution crossing state lines impacts early deaths in each state,
said coauthor Steven Barrett, an associate professor of aeronautics
and astronautics at Massachusetts Institute of Technology in
Cambridge.
Globally, an estimated 4.2 million premature deaths are linked to
outdoor air pollution, mainly from heart disease, stroke, lung
disease, and acute respiratory infections in children, according to
the World Health Organization.
Efforts to address outdoor air pollution have largely focused on
relationships between local sources of pollution and local air
quality. What Barrett and colleagues found is that cross-state
pollution accounts for about half of all premature,
pollution-related deaths.
"Pollution is even less local than we thought," Barrett said in
comments emailed to Reuters Health.
The computer model his team developed for the study took weather
patterns and atmospheric chemistry processes into account and tied
those to data on human exposures and health risks. They used this to
track how each state in the contiguous U.S. affects pollution and
health outcomes in every other state.
The model included data from 2005, 2011 and 2018 on different
sources and types of pollutants, such as sulfur dioxide, ozone and
fine particulates, from seven emissions sectors, including electric
power generation, road transportation, marine, rail, aviation, and
commercial and residential sources.
The team found that electric power plants - which emit sulfur
dioxide from smokestacks - were the biggest contributor to deaths
related to pollution from other states. In 2005, sulfur dioxide from
power plants was involved in 75% of cases of premature deaths from
out-of-state pollutants.
One bright note is that regulatory changes to curb emissions since
2005 have reduced the number of early deaths related to air
pollution by 30%.
The team also found the proportion of premature deaths from
out-of-state emissions is dropping - falling from 53% in 2005 to 41%
in 2018.
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Not all states contribute to the problem equally, the study showed.
Many states in the northern midwest, such as Wyoming and North
Dakota, are "net exporters" of pollution-related health impacts, in
part because of their low populations relative to the amount of
emissions they generate.
States on the east coast, where winds sweep emissions eastward, are
"net importers" of air pollution. New York is hit especially hard,
with 60% of early deaths related to air pollution arising from
out-of-state emissions.
Dr. Peter Muennig, who studies health effects of air pollution at
Columbia University's Mailman School of Public Health in New York
City, applauded the work.
"This is a great study," Muennig, who was not involved in the
research, said in an email.
"Because this study looks at changes over time and geographic
region, it goes far beyond simple correlation," he said.
A key limitation, he said, is that the data are based on models,
which can be complex and prone to error.
Barrett said the researchers tried to quantify areas of uncertainty
in the models.
"Like with climate change, not knowing the exact number doesn't mean
you don't take action, because uncertainty cuts both ways and
reality could be worse than our central estimates, as well as
better," he said.
Barrett said the team has a big archive of data that policymakers
could use to curb some of these deaths.
SOURCE: https://go.nature.com/3buFgKK Nature, February 12, 2020.
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