A new study shows how the timing and location of smoke impacts change in August and September. – ScienceDaily

From the Pacific Northwest to the Rocky Mountains, summers in the west are marked by wildfires and smoke. New research from the University of Utah links the worsening trend of extremely poor air quality events in western regions to wildfire activity, with increasing smoke trends impacting on air quality in September. The work is published in Environmental research letters.

“In a global sense, we can expect the situation to get worse,” says Kai Wilmot, lead author of the study and a doctoral student in the Department of Atmospheric Sciences. “We’re going to see more fire zones burned in the western United States by 2050. If we extrapolate our trends forward, it seems to indicate that many urban centers will struggle to meet standards.” air quality. little time like 15 years. “

Establish connection

Many westerners have seen smoky summer skies in recent years. Last year, dramatic images of an orange-tinted San Francisco Bay area drew attention to the widespread problem of wildfire smoke. Wilmot, from the Pacific Northwest, also saw the smoke and, with his colleagues, looked at trends in extreme air quality events in the West from 2000 to 2019 to see if they correlated. with the summer forest fires.

Using particulate air measurements2.5, or the amount of particles in the air with diameters less than 2.5 microns, from the Environmental Protection Agency and the IMPROVE monitoring network, as well as measurements of the burnt fire area and PM2.5 emitted by these fires, the researchers found consistent trends in air quality that correlated with wildfire activity – but had different spatial patterns in August than in September.

Trends in August and September

Over the years studied, researchers noticed that average air quality deteriorated in the Pacific Northwest in mid August when sensors indicated wildfire smoke events.

“It’s pretty dramatic,” Wilmot says, “that the extreme events are strong enough to mean the average so that we see an overall increase in particulate matter in August across much of the Pacific Northwest and parts of it. from California. The Pacific Northwest seems like it really is. “

The reason for this, he says, is that parts of the Pacific Northwest, British Columbia and northern California, both experience wildfires around August. The mountainous Pacific Northwest, Wilmot says, sits in the middle.

But in September, researchers found wildfire activity was slowing down in British Columbia and moving toward the Rocky Mountains. Smoke is also changing – researchers saw emerging trends correlating smoke from wildfires with declining air quality in September in Wyoming and Montana. “We see the PM2.5 the trends start to accelerate a little more in the Rockies and they become more statistically significant, a little stronger and more spatially consistent, ”says Wilmot.

What about Utah? Study results show that the magnitude and significance of air quality trends increase as you move from southern Arizona and New Mexico to the Pacific Northwest. . In Utah, Wilmot says, air quality trends are almost on the verge of statistical significance, with evidence of the impact of wildfires, but evidence that is weaker than in the northeast. western Pacific and California. “Thinking of events like the transport of smoke from the fires in the Bay Area this summer,” says Wilmot, “I wouldn’t be surprised to see the trends in Utah become more and more compelling with additional data. . “

Looking to the future

Other researchers in other studies have suggested that the future will bring more fire areas burned to the western United States, with increased exposure to smoke from wildfires throughout the United States. West and the impacts of this smoke on human health.

Wilmot notes that the trends researchers see in the Pacific Northwest in August are “pretty robust,” he says, while the September trends in Montana and Wyoming are still “emerging.”

“I think the problem is, with more time, these emerging trends are going to start to look a lot more like what we’re seeing in August,” he says. “I hope it doesn’t, but it seems entirely within the realm of possibility.”

Its next step is to develop simulation models to more precisely link forest fire emissions in urban centers to smoke source regions.

“The big picture,” he says, “aims to help forest management by identifying hot spots of wildfire emissions that are particularly relevant to air quality in the western United States. , so that if we had funds to spend on some sort of intervention to limit wildfire emissions, we would know where to allocate those funds first to get the most out of them. “

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