A new landmark study by Cambridge University has found a strong link between long-term exposure to air pollution and an increased risk of dementia, raising urgent health concerns for countries like India where pollution levels remain consistently high.
Published in The Lancet Planetary Health, the research analysed data from over 29 million people across 51 studies, making it the most comprehensive global review to date on air pollution and dementia. The findings confirm that fine particulate matter (PM2.5), nitrogen dioxide (NO₂), and black carbon (soot) significantly increase the risk of developing the neurodegenerative condition.
What the study found
The study reveals that for every 10 μg/m³ rise in PM2.5 microscopic particles released from vehicles and power plants the risk of dementia increases by 17%. In Delhi, PM2.5 levels frequently exceed 70 μg/m³, almost three times the global safe limit.
Nitrogen dioxide, mostly from vehicular emissions and fossil fuel combustion, was found to increase dementia risk by 3% for every 10 μg/m³. The ITO station in Delhi recently recorded NO₂ levels at 83 μg/m³. Exposure to just 1 μg/m³ of soot increased dementia risk by 13%.
Though Indian pollution watchdogs do not report black carbon separately, it is commonly found in high amounts in urban areas.
How pollution harms the brain
Scientists believe air pollution affects the brain through two main routes: direct entry of fine particles through the nasal cavity into the brain, and through the bloodstream, triggering inflammation and oxidative stress. Both are known factors in dementia progression.
“These pollutants don’t just damage lungs and hearts they reach our brains too, altering cognition and memory over time,” said Dr Christiaan Bredell, lead author of the study.
A growing health emergency
According to WHO, 57 million people were living with dementia globally in 2021, a figure expected to rise to 150 million by 2050. Experts warn that uncontrolled air pollution in developing nations may accelerate this growth, making dementia not just a health concern for the elderly, but a future crisis for entire populations.
The WHO also notes that 99% of the world’s population breathes air that exceeds global safety limits, with low- and middle-income countries facing the worst exposures.
Call for urgent action
Experts say dementia prevention now demands more than just medical care it calls for cleaner air, better urban planning, stricter emissions regulations, and smarter transport policy.
“This study shows dementia prevention is a cross-sector issue. It’s time governments treat air quality as a core part of public health strategy,” Dr Bredell added.
As India battles its annual cycles of smog and urban pollution, the new findings underscore a stark warning: what you breathe could quietly erode your mind over time.