Occupational & environmental · Air pollution and mortality
Ambient Particulate Air Pollution and Daily Mortality in 652 Cities
| Design | Time-series analysis across 652 cities in 24 countries and regions |
|---|---|
| Treatment | Higher ambient particulate concentration |
| Control | Lower ambient particulate concentration |
| Population | Daily mortality records from 652 cities worldwide |
| Follow-up | Varies by city, multiple decades of daily records |
| Primary endpoint | Association between short-term particulate exposure and daily all-cause mortality |
| Result | An increase of 10 µg/m3 in the 2-day moving average of PM10 was associated with a 0.44% increase in daily all-cause mortality (95% CI 0.39 to 0.50), with corresponding increases in cardiovascular and respiratory mortality. Independent associations were seen for both PM10 and PM2.5. |
| Secondary endpoints | Cardiovascular mortality, respiratory mortality, concentration-response shape |
Our data show independent associations between short-term exposure to PM10 and PM2.5 and daily all-cause, cardiovascular, and respiratory mortality in more than 600 cities across the globe.
The trial authors, in the published abstract
The scale is what makes it hard to argue with: 652 cities, consistent associations, no evidence of a safe threshold. A 0.44% increase sounds trivial until it is applied to every death in every city every day. It is the evidential basis for air quality standards being tightened rather than met.
Liu C, Chen R, Sera F, et al. Ambient Particulate Air Pollution and Daily Mortality in 652 Cities. N Engl J Med 2019 Aug 22;381(8):705-715.