Twenty years of air quality improvement erased by wildfires

The devastating wildfires in the United States and Canada have left a significant impact on air quality and public health. Recent studies highlight the alarming effects of these fires, particularly in the context of efforts to combat air pollution.

Toll of wildfires on air and health

A comprehensive study spanning two decades (2000-2020) has revealed a concerning increase in air pollution in the western U.S., primarily due to the growing intensity and frequency of wildfires. This trend has resulted in an estimated 670 additional premature deaths annually in the region.

The researchers emphasize that these wildfires have negated the progress made through federal air quality improvement initiatives, largely driven by reductions in automobile emissions. Jun Wang, the lead corresponding author and a professor at the University of Iowa, expressed deep concern about the situation.

“Our air is supposed to be getting cleaner, mainly due to EPA regulations on emissions. However, the fires have limited or erased these air-quality gains,” he stated.

Wang further noted the detrimental impact of wildfires in fire-prone areas and their surroundings, which effectively undermines two decades of EPA efforts to improve air quality. He expounded, “In other words, all the efforts for the past 20 years by the EPA to make our air cleaner basically have been lost in fire-prone areas and downwind regions. We are losing ground.”

Studying wildfires and air quality

The research team meticulously calculated the concentration of black carbon, a harmful air pollutant linked to respiratory and heart diseases. They used a detailed grid system covering the continental U.S. to map these concentrations.

Findings show a 55% increase in black carbon in the western U.S., predominantly due to wildfires. The highest rates of premature mortality were observed in this region, exacerbated by smoke from both local and Canadian wildfires. The researchers caution that the figure of 670 additional deaths per year is conservative, given the incomplete understanding of black carbon’s health impacts.

“Wildfires have become increasingly intensive and frequent in the western U.S., resulting in a significant increase in smoke-related emissions in populated areas,” Wang and his team write. “This has likely contributed to a decline in air quality and an increase in attributable mortality.”

The study also sheds light on the effects of wildfires on the Midwest, where transported smoke has minimally impacted health so far. However, Wang warns of potential worsening air quality if wildfire incidents increase. Interestingly, the eastern U.S. did not experience significant air quality declines during the study period.

Data from multiple sources

The team used a combination of satellite data and information from 500 ground-based air quality monitoring stations. Recognizing the limitations of surface station data, especially in rural areas, they employed deep learning techniques to estimate black carbon concentrations with higher accuracy.

The calculation of premature deaths involved a formula considering life span, black carbon exposure, and population density. “This is the first time black carbon concentrations have been examined everywhere, and at such a high resolution,” Wang noted.

Future study and implications

Jing Wei, the study’s lead author, played a pivotal role in collecting and analyzing satellite data on fine particulates and their health impacts. Now at the University of Maryland’s Earth System Science Interdisciplinary Center, Wei highlights the counteractive effect of increasing wildfires against the reduction in anthropogenic emissions, exacerbating air pollution and heightening health risks.

“The increasing number and intensity of wildfires in the U.S. counteract or even overshadow the reduction in anthropogenic emissions, exacerbating air pollution and heightening the risks of both morbidity and mortality,” says Wei.

In summary, the study serves as a crucial reminder of the ongoing battle against air pollution, where natural disasters like wildfires pose significant challenges. It calls for a renewed focus on mitigating these environmental threats to safeguard public health and maintain air quality improvements.

The full study is published in the journal The Lancet Planetary Health.

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