3-year wildfire smoke exposure raises all-cause, nonaccidental, neoplasm mortality risk
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Key takeaways:
- Increases in wildfire-related fine particulate matter corresponded to heightened mortality risks.
- More studies on the impact of long-term exposure to wildfire pollution are needed.
Risk for all-cause, nonaccidental and neoplasm mortality was heightened with exposure to elevated levels of wildfire-related fine particulate matter, according to study results published in the Journal of Hazardous Materials.
“Given the recent levels in North America caused by the Canadian wildfires, our study linking long-term exposure to wildfire-related PM2.5 and mortality suggest[s] that further research is urgently needed to provide more scientific evidence on this topic,” Shanshan Li, PhD, associate professor at the School of Public Health and Preventive Medicine at Monash University, said in a university press release.
In a longitudinal analysis, Li and colleagues evaluated 492,394 adults (mean age, 56.5 years; 45.5% men; 88.4% white) aged 38 to 73 years from the UK Biobank to understand how long-term exposure (3 years) to wildfire related PM2.5 impacts mortality.
Using participants’ home addresses, researchers captured their exposure to wildfire-related PM2.5 that was within 10 km of their house. In this cohort, 457.3 g/m3 (standard deviation, 42.8 g/m3) was the 3-year average concentration, and 459.7 g/m3 was the median concentration.
To calculate mortality risk, time-varying Cox regression models were used, which were adjusted for several potential covariates: age, sex, ethnicity, education, employment status, BMI, average total household income, non-wildfire PM2.5, smoking status, alcohol drinking status and Townsend Deprivation Index.
Researchers observed an average follow-up period of 11.2 years, during which 27,080 individuals died.
According to researchers, a 0.4% increased risk for both all-cause mortality (adjusted HR = 1.004; 95% CI, 1.001-1.006) and nonaccidental mortality (aHR = 1.004; 95% CI, 1.002-1.006) occurred with each 10 g/m3 rise in wildfire-related pollution.
Exposure to this type of pollution was also linked to a 0.5% heightened risk for neoplasm death (aHR = 1.005; 95% CI, 1.002-1.008) with each increase by 10 g/m3.
When assessing the impact of exposure to this type of PM2.5 on death due to a cardiovascular, respiratory or mental disease, researchers did not observe any significant relationships in the adjusted models.
Researchers also evaluated every covariate, except non-wildfire PM2.5, as modifiers, and found that none of them had modification effects on the relationship between wildfire-related PM2.5 exposure and all-cause mortality.
“Our findings provide scientific evidence on long-term impacts of wildfire-related PM2.5 exposure on mortality in the U.K., which will be of vital importance for developing better health response plan[s] and targeting health intervention strategies from wildfire-related PM2.5 exposure,” Li and colleagues wrote.
Reference:
- World’s biggest study of wildfire smoke impact reveals alarming long-term health impacts. https://www.eurekalert.org/news-releases/993346. Published June 21, 2023. Accessed June 22, 2023.
Perspective
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The findings of this study are significant in supporting known literature about the effects of PM2.5 on morbidity and premature deaths certainly in elevated short-term exposure. I did find it a bit surprising that cardiac- and lung disease-specific mortality was not shown to be elevated in this long-term exposure study. We know that those individuals at risk for morbidity and mortality related to poor air quality of elevated PM2.5 are the very young, the elderly, those that are pregnant and those with known cardiac and pulmonary disorders.
The exacerbation of chronic diseases by wildfire PM2.5 is a definite occurrence in my practice and well cited in the literature for short term exposure.
Physicians need to remind patients, especially those at risk with lung and heart disease, that air quality can play a role in upsetting the stability of their conditions. Checking the air quality at Airnow.gov or other air monitoring agencies on a regular basis can help patients plan their activities for the day and certainly call for limits on outdoor exposure when the air quality reaches moderate or worse levels. Physicians should educate their patients on the correct precautions to take if they are in an area with elevated PM2.5 due to wildfires. People can experience elevated PM2.5 from wildfires locally as well as thousands of miles away. Information about how people can protect themselves from wildfires smoke is available at Lung.org/wildfires.
I believe further research with similar large cohorts may be able to address the confounding issues pointed to in this article and may indeed show the disease-specific premature mortality that we suspect may be present in those with cardiac and pulmonary conditions. With the ever present and growing likelihood that wildfires are becoming more prevalent, learning more about the long-term consequences of PM2.5 exposure is very important.
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