Air pollution may increase dementia risk, Harvard researchers find: ‘A big step in providing actionable data’

Air pollution exposure may lead to an increased risk for dementia, according to Harvard researchers who call this new finding “a big step in providing actionable data” for the EPA.

The Harvard T.H. Chan School of Public Health scientists found consistent evidence of a link between the exposure to fine particulate air pollutants (PM2.5) and dementia.

The Environmental Protection Agency is looking at a proposal to strengthen PM2.5 regulations, and the researchers emphasized that their findings support the public health importance of limiting exposure to these fine particulate air pollutants.

“This is a big step in providing actionable data for regulatory agencies and clinicians in terms of making sense of the state of the literature on this hugely important health topic,” said lead author Marc Weisskopf, who’s a Cecil K. and Philip Drinker professor of Environmental Epidemiology and Physiology.

“The results can be used by organizations like the Environmental Protection Agency, which is currently considering strengthening limits on PM2.5 exposure,” Weisskopf added. “Our findings support the public health importance of such a measure.”

More than 57 million people worldwide are living with dementia, and estimates suggest that number will jump to 153 million people by 2050.

Up to 40% of these cases are thought to be linked to potentially modifiable risk factors, such as exposure to air pollutants.

The Harvard researchers scanned more than 2,000 studies and identified 51 that evaluated an association between ambient air pollution and clinical dementia, all published within the last 10 years.

The researchers found consistent evidence of an association between PM2.5 and dementia, even when annual exposure was less than the current EPA annual standard of 12 micrograms per cubic meter of air. They also found evidence suggesting links between dementia and nitrogen oxide and nitrogen dioxide, though that data was more limited.

The researchers noted that air pollution’s estimated association with dementia risk is smaller than that of other risk factors, such as education and smoking. However, because of the number of people exposed to air pollution, the population-level health implications could be significant.

“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,” Weisskopf said. “Exposure to PM2.5 and other air pollutants is modifiable to some extent by personal behaviors — but more importantly through regulation.”