West Coast exposed to 7 times more wildfire pollution than standards allow, study says
As temperatures rise and humidity levels drop, wildfire seasons are becoming more severe, along with the tiny inhalable particles smoke throws into the air.
A new study reveals that the northwestern U.S. is exposed to six to seven times more particulate matter from wildfire smoke than Environmental Protection Agency standards deem safe for a 24-hour period.
People living in more than half of U.S. states are at risk from the consequences of inhaling smoky particles, but those in Washington, California, Oregon, Wisconsin and Colorado are the “hardest hit,” according to the paper published last month in the journal Atmospheric Chemistry and Physics.
All the most affected states have populations greater than 4 million, including 3 million people with asthma who are more at risk of troubled breathing, irritated sinuses and chest pain, among other health issues.
What’s more, wildfire smoke that travels with the wind across long distances typically contains even smaller particles than stagnant smoke. Inhaling these “fine-fraction” particles can “significantly affect the health of children, adults and vulnerable groups,” the team said.
“Although wildfires are often episodic and short term, high frequency of fire occurrence and increasingly longer durations of summertime wildfires in recent years have made them now a long-term influence on public lives,” The University of Alabama in Huntsville researchers said in their study. “Our results show a significant increase in pollution in a short time period in most of the US states … which affects millions of people.”
The researchers used 17 days of satellite and ground observational data from 2011, a year of low fire activity, and compared it with 17 days of data from 2018, a year with high fire activity. A total of 1,003 fire monitoring sites in the U.S. were included in the study.
With the help of statistical models, the team estimates that nearly 29 states saw increased PM2.5 — an EPA term used to describe fine inhalable particles that are 2.5 micrometers and smaller in size — during the active fire year. Fifteen of those states violate EPA safety standards, with double the PM2.5 concentrations compared to the inactive fire year.
In Washington, for example, average PM2.5 jumps from 5.87 in 2011 to 46.47 µg m−3 in 2018. That’s eight times higher.
The EPA standard that is considered safe is 35 µg m−3, or micrograms per cubic meter of air.
Likewise, PM2.5 concentrations in Oregon saw a 7-fold increase from the inactive to active fire year.
Researchers also learned that just one wildfire event in 2018 exposed up to 52% of Americans to harmful particulate matter.
Zhixin (May) Xue, lead author of the study, said a significant amount of wildfire pollution blanketing the U.S. comes from fires in Canada.
Fire radiative power (FRP) — the amount of radiant energy burning vegetation releases over time — is about five times greater in Canadian wildfires than those in California. So, the researchers assume much of the pollution reaching northwestern states in the U.S. are coming from that direction.
However, “this influence of Canadian wildfires on U.S. air quality is only a rough quantity estimation, and thus additional work is needed to understand long-range transport smoke pollution and its impact on public health,” the team notes.
This story was originally published August 20, 2021 at 1:36 PM with the headline "West Coast exposed to 7 times more wildfire pollution than standards allow, study says."
