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Study Warns That Wildfire Smoke Contains Dangerous Pollutants
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Wildfire smoke contains pollutants hazardous to health, including fine particulate matter (PM2.5), which has been linked to increased mortality and morbidity.
A new study by the Barcelona Institute for Global Health (ISGlobal), a center supported by the "la Caixa" Foundation, provides strong evidence that PM2.5 from wildfires poses a higher mortality risk than particles unrelated to fires.
The findings, published in *The Lancet Planetary Health*, also suggest that wildfire smoke-related mortality may be underestimated by 93%.
A sample of 541 million people
The study relied on data from the EARLY-ADAPT project, which includes daily mortality records from 654 contiguous regions across 32 European countries, representing a population of 541 million people. The team combined this data with daily estimates of wildfire-related and non-wildfire-related PM2.5 from 2004 to 2022.
To analyze the short-term effects of wildfire smoke on mortality, statistical models were used to detect effects with a time lag, as health issues may not manifest immediately. The analysis covered all-cause mortality, respiratory mortality, and cardiovascular mortality.
The results showed that exposure to higher levels of wildfire-related fine particles increased the risk of death within seven days after exposure.
Specifically, for every increase of one microgram per cubic meter (1 µg/m³) in PM2.5 concentration, all-cause mortality rose by 0.7%, respiratory mortality by 1%, and cardiovascular mortality by 0.9%.
Underestimated Mortality
The study estimated that, during the analysis period, short-term exposure to wildfire-derived PM2.5 was responsible for an average of 535 annual all-cause deaths, including 31 from respiratory diseases and 184 from cardiovascular causes.
In contrast, only an average of 38 annual deaths would be expected from wildfire smoke if wildfire-derived PM2.5 had the same mortality effect as fine particles from all other sources.
This assumption, used in previous studies, would result in a 93% underestimation of mortality. This difference highlights the importance of considering the specific source of particles.
"Human-induced climate change is contributing to the increasing frequency and intensity of wildfires, as it creates favorable conditions for their spread and raises the number of days with very high or extremely high fire risk," notes Anna Alari, a researcher at ISGlobal and the study's lead author.
"Improving estimates of mortality attributable to wildfire-related PM2.5 will help better track the public health burden of this climate change-linked threat," she adds.
Regional Differences
The analysis reveals some regional heterogeneity in the associations between wildfire-related PM2.5 exposure and mortality. Bulgaria, Romania, Hungary, and Serbia were the most affected countries. In contrast, some highly exposed regions in Portugal and Spain showed negative and imprecise associations.
"Possible explanations could relate to regional and national wildfire adaptation and management strategies. However, further studies are needed to identify the factors behind this regional variability," says Cathryn Tonne, a researcher at ISGlobal and the study's senior author.
Source:La Sexta
