Wildfires in the Pacific Northwest alter air pollution patterns across North America

According to new research, increasing large and intense wildfires in the Pacific Northwest are changing the seasonal pattern of air pollution and causing a spike in unhealthy pollutants in August. According to the study, smoke undermines clean air gains and poses potential health risks to millions of people.

The study, led by scientists at the National Center for Atmospheric Research (NCAR), discovered that carbon monoxide levels – a gas indicating other air pollutants – increased dramatically as wildfires spread in August.

"Wildfire emissions have increased so significantly that they are changing the annual pattern of air quality across North America," said lead author and NCAR scientist Rebecca Buchholz. "It's clear that there's a new peak of air pollution in August that didn't exist before."

Although carbon monoxide is not a significant health concern in the open air, it does indicate the presence of more dangerous pollutants such as aerosols (airborne particulates) and ground-level ozone, which tend to form on hot summer days.

The researchers tracked wildfire emissions over the past two decades using satellite-based observations of atmospheric chemistry and global fire inventories, and computer modeling to assess the potential impacts of the smoke.

The findings, according to Buchholz, were particularly striking because carbon monoxide levels have been decreasing otherwise, both globally and in North America, due to advances in pollution-control technologies.

The findings were published in Nature Communications this week. The examination was funded by the National Science Foundation of the United States, 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.

Impacts on air pollution are becoming more severe.

Due to climate change, increased development, and land use policies, wildfires have been on the rise in the Pacific Northwest also other parts of North America. As a result, fires are becoming a more significant source of air pollution, as emissions from human activities decrease due to more efficient combustion processes in automobiles and industrial facilities.

Buchholz and her colleagues used data from two NASA Terra satellite instruments to analyze the effects of fires: MOPITT (Measurements of Pollution in the Troposphere), which has tracked carbon monoxide continuously since 2002, and MODIS (Moderate Resolution Imaging Spectrometer), which detects fires and provides information on aerosols. They also looked at four wildfire emissions inventories that rely on MODIS data.