Population aging eclipses the benefits of improving air quality

China's successful efforts to reduce fine particulate air pollution (PM2.5) since 2013 have delivered measurable environmental gains, yet dementia deaths attributed to this exposure climbed dramatically—from 106,571 in 2013 to 171,420 by 2024. The mechanism is established: inhaled particles trigger systemic chronic inflammation that compromises cognitive function, particularly in advanced age. This health impact assessment, integrating exposure, population, and mortality data from multiple sources, exposes a central paradox in modern medicine: while clean air policies prevented approximately 11,000 deaths over the period, demographic aging generated roughly 67,000 additional dementia deaths, becoming the dominant driver of rising incidence. For longevity-focused readers, the implication cuts deeper—aging itself, not merely its risk factors, demands pharmaceutical and therapeutic intervention at the root level, making such research economically urgent and morally unavoidable.