Well that was a fun detour. The clincher is here, a Global Burden of Disease Study in 2010: https://sci-hub.mksa.top/10.1016/S0140-6736(12)61766-8 https://sci

Well that was a fun detour. The clincher is here, a Global Burden of Disease Study in 2010: https://sci-hub.mksa.top/10.1016/S0140-6736(12)61766-8 https://sci-hub.mksa.top/10.1016/S0140-6736(12)61766-8 That is where they draw a line from air pollution to risk, with lots of statistics to cancel out other factors. Its beyond my depth. ---- This page was useful: ttps://www.who.int/data/gho/data/indicators/indicator-details/GHO/ambient-air-pollution-attributable-dalys-(per-100-000-population) -> Metadata > Burden of disease is calculated by first combining information on the increased (or relative) risk of a disease resulting from exposure, with information on how widespread the exposure is in the population (in this case, the annual mean concentration of particulate matter to which the population is exposed). This allows calculation of the 'population attributable fraction' (PAF), which is the fraction of disease seen in a given population that can be attributed to the exposure, in this case the annual mean concentration of particulate matter. Applying this fraction to the total burden of disease (e.g. cardiopulmonary disease expressed as deaths or DALYs), gives the total number of deaths or DALYs that results from ambient air pollution. ---- And the overall methodology is something called DALYs - Disability Adjusted Life Years https://www.who.int/data/gho/indicator-metadata-registry/imr-details/158 https://www.who.int/data/gho/indicator-metadata-registry/imr... https://www.who.int/healthinfo/statistics/GlobalDALYmethods_2000_2011.pdf?ua=1 https://www.who.int/healthinfo/statistics/GlobalDALYmethods_... That second link was a good basic read on what DALY means - its deaths due to a cause, weighted by "lost years" (so if life expectancy is 92 and someone died at 30, that would be weighted higher than someone dying at 80 for the same cause) PLUS years of healthy life lost even if it does not result in death - which is sort of a weighting based on severity of disease, where like say a person living with a disease severity of 0.2 would mean each year counts as 4/5th a year of a healthy life.