Pacific Northwest wildfires alter air pollution patterns across North
America
Increase in August pollution could have far-reaching health implications
Date:
April 19, 2022
Source:
National Center for Atmospheric Research/University Corporation
for Atmospheric Research
Summary:
Increasingly large and intense wildfires in the Pacific Northwest
are altering the seasonal pattern of air pollution and causing
a spike in unhealthy pollutants in August, according to new
research. The smoke is undermining clean air gains, posing potential
risks to the health of millions of people, according to the study.
FULL STORY ========================================================================== Increasingly large and intense wildfires in the Pacific Northwest are
altering the seasonal pattern of air pollution and causing a spike
in unhealthy pollutants in August, new research finds. The smoke is
undermining clean air gains, posing potential risks to the health of
millions of people, according to the study.
==========================================================================
The research, led by scientists at the National Center for Atmospheric
Research (NCAR), found that levels of carbon monoxide -- a gas that
indicates the presence of other air pollutants -- have increased sharply
as wildfires spread in August. Carbon monoxide levels are normally lower
in the summer because of chemical reactions in the atmosphere related
to changes in sunlight, and the finding that their levels have jumped
indicates the extent of the smoke's impacts.
"Wildfire emissions have increased so substantially that they're
changing the annual pattern of air quality across North America," said
NCAR scientist Rebecca Buchholz, the lead author. "It's quite clear that
there is a new peak of air pollution in August that didn't used to exist." Although carbon monoxide generally is not a significant health concern outdoors, the gas indicates the presence of more harmful pollutants,
including aerosols (airborne particulates) and ground-level ozone that
tends to form on hot summer days.
The research team used satellite-based observations of atmospheric
chemistry and global inventories of fires to track wildfire emissions
during most of the past two decades, as well as computer modeling to
analyze the potential impacts of the smoke. They focused on three North American regions: the Pacific Northwest, the central United States,
and the Northeast.
Buchholz said the findings were particularly striking because carbon
monoxide levels have been otherwise decreasing, both globally and across
North America, due to improvements in pollution-control technologies.
==========================================================================
The study was published this week in Nature Communications.The research
was funded in part by the U.S. National Science Foundation, NCAR's
sponsor. The paper was co-authored by researchers from the University
of Colorado, Boulder; Columbia University; NASA; Tsinghua University;
and Colorado State University.
Increasing impacts on air pollution Wildfires have been increasing in the Pacific Northwest and other regions of North America, due to a combination
of climate change, increased development, and land use policies. The fires
are becoming a larger factor in air pollution, especially as emissions
from human activities are diminishing because of more efficient combustion processes in motor vehicles and industrial facilities.
To analyze the impacts of fires, Buchholz and her collaborators
used data from two instruments on the NASA Terra satellite: MOPITT (Measurements of Pollution in the Troposphere), which has tracked
carbon monoxide continually since 2002; and MODIS (Moderate Resolution
Imaging Spectrometer), which detects fires and provides information
on aerosols. They also studied four inventories of wildfire emissions,
which rely on MODIS data.
The scientists focused on the period from 2002, the beginning of a
consistent and long-term record of MOPPIT data, to 2018, the last year
for which complete observations were available at the time when they
began their study.
==========================================================================
The results showed an increase in carbon monoxide levels across North
America in August, which corresponded with the peak burning season of
the Pacific Northwest. The trend was especially pronounced from 2012 to
2018, when the Pacific Northwest fire season became much more active,
according to the emissions inventories. Data from the MODIS instrument
revealed that aerosols also showed an upward trend in August.
To determine whether the higher pollution levels were caused by the fires,
the scientists eliminated other potential emission sources. They found
that carbon monoxide levels upwind of the Pacific Northwest, over the
Pacific Ocean, were much lower in August -- a sign that the pollution
was not blowing in from Asia.
They also found that fire season in the central U.S. and the Northeast
did not coincide with the August increase in pollution, which meant
that local fires in those regions were not responsible. In addition,
they studied a pair of fossil fuel emission inventories, which showed
that carbon monoxide emissions from human activities did not increase
in any of the three study regions from 2012 to 2018.
"Multiple lines of evidence point to the worsening wildfires in the
Pacific Northwest as the cause of degraded air quality," Buchholz
said. "It's particularly unfortunate that these fires are undermining the
gains that society has made in reducing pollution overall." Risks to
human health The findings have implications for human health because
wildfire smoke has been linked to significant respiratory problems, and it
may also affect the cardiovascular system and worsen pregnancy outcomes.
Buchholz and her co-authors used an NCAR-based computer model, the
Community Atmosphere Model with a chemistry component, to simulate
the movement of emissions from the Pacific Northwest fires and their
impact on carbon monoxide, ozone, and fine particulate matter. They
ran the simulations on the Cheyenne supercomputer at the NCAR-Wyoming Supercomputing Center. The results showed the pollutants could affect
more than 130 million people, including about 34 million in the
Pacific Northwest, 23 million in the Central U.S., and 72 million in
the Northeast.
Although the study did not delve deeply into the health implications of
the emissions, the authors looked at respiratory death rates in Colorado
for the month of August from 2002 to 2011, compared with the same month
in 2012 to 2018. They chose Colorado, located in the central U.S. region
of the study, because respiratory death rates in the state were readily obtainable.
They found that Colorado respiratory deaths in August increased
significantly during the 2012-2018 period, when fires in the Pacific
Northwest -- but not in Colorado -- produced more emissions in August.
"It's clear that more research is needed into the health implications of
all this smoke," Buchholz said. "We may already be seeing the consequences
of these fires on the health of residents who live hundreds or even
thousands of miles downwind."
========================================================================== Story Source: Materials provided by National_Center_for_Atmospheric_Research/University Corporation_for_Atmospheric_Research. Original written by David
Hosansky. Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Rebecca R. Buchholz, Mijeong Park, Helen M. Worden, Wenfu Tang,
David P.
Edwards, Benjamin Gaubert, Merritt N. Deeter, Thomas Sullivan,
Muye Ru, Mian Chin, Robert C. Levy, Bo Zheng, Sheryl Magzamen. New
seasonal pattern of pollution emerges from changing North American
wildfires.
Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-29623-8 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220419091846.htm
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