How does air pollution affect the brain?

A: Air pollution is increasingly being recognised as an important threat to brain health. Research has demonstrated that exposure to airborne pollutants like fine particulate matter (PM2.5), nitrogen dioxide (NO₂), and ozone can affect brain structure, functioning, and even increase the risk of neurological and mental health disorders.

On July 24, for example, scientists reported in The Lancet Planetary Health that after analysing data in 51 studies representing more than 26 million adults across four continents and follow‑ups of up to 23 years, every additional 5 micrograms per cubic m (µg/m³) of PM2.5 particles in the air increased the risk of dementia by about 8%. They also found a 10 µg/m³ increase in NO₂ increased the same risk by around 3% and a 1 µg/m³ increase of soot did so by 13%.

The researchers rated the overall certainty of the evidence to be ‘moderate’. Because the harmful pollutants mainly come from traffic, industry, and burning fuels, they argued that improving air quality could meaningfully cut future dementia risk in the population, lower healthcare expenses and easing familial burdens.