Air Pollution May Increase Risk Of Dementia, Analysis Finds

Breathing polluted air has been linked to a greater risk of dementia, according to a new analysis from Harvard University researchers.

The scientists looked at 10 years' worth of studies that evaluated an association between ambient air pollution and clinical dementia. Most of the research focused on fine particulate air pollutants, known as PM2.5.

The researchers at the Harvard T.H. Chan School of Public Health found consistent evidence of an association between PM2.5 and dementia, even when annual exposure was less than current Environmental Protection Agency standards of 12 micrograms per cubic meter of air.

An increase of 2 micrograms per cubic meter of air in average annual exposure to PM2.5 results in a 17% increase in risk for developing dementia, according to the study published in The BMJ medical journal. The researchers also found smaller increases in risk from breathing nitrogen oxide and nitrogen dioxide, pollutants that come from auto exhaust.

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“Given the massive numbers of dementia cases, identifying actionable modifiable risk factors to reduce the burden of disease would have tremendous personal and societal impact,” lead author Marc Weisskopf, a professor of Environmental Epidemiology and Physiology, said in a news release. “Exposure to PM2.5 and other air pollutants is modifiable to some extent by personal behaviors — but more importantly through regulation.”

Worldwide, more than 57 million people are living with dementia, according to the researchers. That number is expected to rise to 153 million by 2050. As many as 40% of these cases are thought to be linked to potentially modifiable risk factors, such as exposure to air pollutants.

The PM2.5 particles can penetrate deep into the lungs and trigger asthma attacks, too.

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The particles can come from construction sites, unpaved roads, fields, smokestacks or fires, according to the EPA. They also form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides.

In January, the EPA proposed lowering the ambient air quality standard for fine particle pollution from 12 micrograms per cubic meter to to between 9 and 10 micrograms per cubic meter.

The agency estimated an annual PM2.5 standard at a level of 9 micrograms per cubic meter would prevent up to 4,200 premature deaths per year and result in as much as $43 billion in net health benefits in 2032. Final standards are expected later this year after hearings are held.

“Our findings support the public health importance of such a measure,” Weisskopf said.

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