Which air pollutants cause brain damage leading to dementia?

After sifting through studies conducted over a decade, scientists at Harvard University have a reason to believe that breathing in polluted air can lead to clinical dementia in humans, primarily because of fine particulate air pollutants, known as PM2.5, Weather.com reported.

The researchers at the Harvard TH Chan School of Public Health have discovered evidence that ties PM2.5 and dementia, even with a yearly exposure that is far lower than current Environmental Protection Agency standards of 12 micrograms per cubic meter of air.

According to the research report published in The BMJ medical journal, 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. The researchers also detected that inhaling nitrogen oxide and nitrogen dioxide that come with pollutants from auto exhausts the risks increase.

“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 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.