The risk of dementia increases with worsening air quality, according to a new study by Harvard researchers. According to them, measures to reduce air pollution could have a beneficial impact not only on lung health, but also on the brain.
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In a meta-analysis of 14 studies conducted over the past 10 years, scientists found that exposure to particulate matter smaller than 2.5 microns in diameter (PM2.5) is associated with an increased risk of dementia.
More specifically, “every 2 μg/m3 increase in the average annual concentration of PM2.5 is associated with a 4% risk of developing dementia,” says Professor Marc Weisskopf, from the Harvard TH Chan School of Public Health in Boston, IN A PRESS.
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O research however, precedent published in the British Medical Journal indicates that the risk of dementia is at least 40% higher when we are constantly exposed to these particulates.
“The results obtained can be used by organizations such as the Environmental Protection Agency [EPA], which is currently considering strengthening PM2.5 exposure limits. Our findings support the public health importance of such a measure,” Weisskopf added.
Earlier this year, the EPA sought to tighten the national annual limit on particulate matter pollution by proposing updates to the National Ambient Air Quality Standards for Fine Particulate Matter with the goal of lowering the primary annual standard for PM2.5 to 9.0 -10.0 µg/m3, from the current 12.0 µg/m3.
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While air pollution is considered a modifiable risk factor for dementia globally, PM2.5 concentrations in major cities vary widely, from 10µg/m3 in Toronto, Canada to over 100µg/m3 in Delhi, India, it is also shown in the scientists’ report.
“Evidence that a reduction in air pollution is associated with a lower incidence of dementia is only now emerging,” Andrew Sommerlad and Kathy Liu, both of University College London, note in an editorial.
This new analysis highlights many uncertainties about the link between air pollution and dementia risk.
“Given the massive number of dementia cases, identifying modifiable risk factors to reduce the burden of the disease would have tremendous personal and societal impact. Exposure to PM2.5 and other air pollutants is modifiable to some extent through personal behaviors, but more importantly through regulations,” the researchers concluded.
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Sources:
Wilker E.H. et al., „Ambient air pollution and clinical dementia: Systematic review and meta-analysis”, BMJ 2023; DOI: 10.1136/bmj-2022-071620
Sommerlad A., Liu K.Y., „Air pollution and dementia: Evidence of a link supports need for pollution control efforts”, BMJ 2023; DOI: 10.1136/bmj.p655
