A recent study published in The BMJ has found that exposure to air pollution, including fine particulate matter (PM2.5) and nitrogen dioxide and nitrogen oxide, is linked to an increased risk of dementia, even at levels below current US, UK, and European air quality standards. The study analyzed 16 studies from North America and Europe and found that higher exposure to fine particulate pollution was associated with an increased risk of dementia. Studies that actively assessed participants reported a stronger association between dementia risk and air pollution than studies using passive surveillance methods. The study did not find an association between ozone and dementia.
The researchers suggest that public health should limit exposure to PM2.5 and other air pollutants to reduce the risk of dementia. However, the study also acknowledges the limitations of their findings, including concerns related to risk of bias, which may have influenced the results.
In a linked editorial, researchers note that PM2.5 concentrations in major cities vary considerably, from below 10µg/m3 in some cities to more than 100µg/m3 in others, meaning air pollution has the potential to substantially affect dementia risk globally.
Effective measures to reduce air pollution will likely require global legislation and policy programs. These may focus on a transition to clean and renewable energy sources, reduced energy consumption, and changes in agriculture. Any positive effect on dementia and general health would be accompanied by an important impact on climate change and biodiversity, making reducing air pollution a global health and humanitarian priority