Smoke from forest fires increases risk of preterm birth (study)

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Exposure to smoke from wildfires during pregnancy increases the risk of preterm labor – a risk that is only getting worse, according to a new study from Stanford University.

The study, published in Environmental Research, found that up to 7,000 additional preterm births in California could be attributed to exposure to smoke from wildfires between 2007 and 2012. According to the authors, preterm births are those that occur before 37 weeks of pregnancy, when they are incomplete. developing fetuses may increase the risk of neurodevelopmental, gastrointestinal and respiratory complications, as well as death.

During the smokiest season covered by the study, 2008, the authors found that forest fires may have contributed to more than 6% of preterm births. That year, a severe thunderstorm, coupled with strong winds and high temperatures, paved the way for particularly intense conditions, according to a press release accompanying the study.

But the devastation that struck in 2008 has already been overtaken by that of 2020, a season in which smoke exposure was 2.5 times worse than in 2008, according to study co-author Marshall. Burke. And the authors fear this phenomenon will repeat itself in 2021.

“2020 doesn’t look all that unusual compared to what we might expect in the future,” Stanford environmental economist, The Hill Burke, told The Hill Burke. “Unfortunately, we should see it as a new normal.”

California is struggling with one of the worst wildfire seasons in its history. The Dixie Fire, northeast of San Francisco, was still expanding after five weeks and only 37% was contained as of Sunday, according to the Associated Press. The Caldor fire, which erupted on August 14, burned down the Sierra Nevada and had no containment on Sunday, while the French fire in Southern California was only 10% contained, reported the AP.

The fires are ravaging a state still reeling from what Cal Fire has described as the “2020 Fire Siege,” which burned some 4 million acres and generated one of the worst daily air pollution ever documented in California.

Smoke from forest fires is particularly dangerous because of its high levels of PM 2.5 – particles with a diameter of 2.5 microns, or 30 times smaller than the diameter of a single human hair, according to the ‘Environmental Protection Agency. These particles can penetrate deep into the lungs and sometimes even into the bloodstream, the EPA said.

The Stanford study builds on an established link between particle pollution and adverse birth outcomes, but it is the first to identify the effects of smoke from wildfires on early births, according to the Press release.

To establish this correlation, the authors analyzed satellite data on the National Oceanic and Atmospheric Administration smoke plume in 2,610 postal codes for the 2007-2012 window. They then combined this data with estimates of ground-level PM 2.5 pollution, developed using a machine learning algorithm that merged data from air quality sensors, satellite observations and computer models that track how pollutants move through the atmosphere.

Data on preterm births comes from California birth registries and excludes twins and higher multiples, which usually arrive early due to other factors, according to the press release. After taking into account other factors related to the risk of preterm birth, the authors investigated how the patterns of such births in each postal code varied with increases in the number and intensity of smoke days.

“We’re seeing remarkable consistency between households,” Burke told The Hill.

Ultimately, the authors found that each day of exposure to smoke during pregnancy increased the risk of preterm birth, regardless of race, ethnicity or income, according to the release. A full week of exposure meant a 3.4% higher risk compared to a mother who had no exposure to smoke from a forest fire, while the greatest impact occurred in during the second trimester.

Scientists have yet to determine the precise health impacts of smoke from forest fires, which has a different chemical composition from other sources of PM 2.5, such as agriculture, tailpipe emissions and l industry, according to the press release.

But one potential explanation for the increase in early births, according to the authors, is that smoke can trigger an inflammatory response that triggers the birthing process. They recognized that this risk is low compared to other factors that contribute to a healthy and full term delivery.

“However, in a context where we know so little about why some women give birth too early, prematurely, and why others don’t, finding clues like this helps us begin to piece together the bigger case. -head, “co-author Gary Shaw, a professor of pediatrics and co-principal investigator of the March of Dimes Prematurity Research Center at Stanford, said in the press release.

Sam Heft-Neal, senior author and researcher at the Stanford Center on Food Safety and the Environment, warned that in the future, intense exposure to such smoke will continue to increase, “due to a confluence of factors “like climate change and fire. deletion.

“As a result, the health burden of exposure to smoke – including premature births – is likely to increase,” Heft-Neal said in the press release.

A short-term solution for pregnant women is to stay indoors or wear an appropriate mask outside, according to Shaw. Over the long term, the authors said their research demonstrates the value of investing in forest fire mitigation, such as prescribed burns and forest thinning.

“There is a lot of evidence that prescribed burns are an inexpensive way to reduce the likelihood of these really serious fires,” Burke told The Hill.

Since preterm births cost the national health care system an estimated $ 25 billion each year, Burke argued that even a small reduction in the risk of preterm birth could generate “huge benefits for society.”

The average societal cost of each preterm birth is around $ 65,000, which means that in 2008, the societal cost of exposure to smoke in California was around $ 130 million, Burke estimated. He calculated that in 2020, with roughly 2.5 times the exposure, the associated costs would be closer to $ 325 million.

The cost estimate for prescribed burns is a bit more “everywhere,” Burke explained, noting that $ 1,000 per acre is an often-used metric. If California needs around 1 million acres to process, that would require an investment of around $ 1 billion, he said.

With those numbers in mind, Burke explained that premature births alone could justify about a third of what California would have to spend on mitigating the risk of wildfires.

“But the necessary expenses cannot be justified solely by the effects of preterm births,” he added.


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