concentration-response function

Agencies do not count the people killed by air pollution one by one. They estimate the share of deaths attributable to it, and the concentration-response function is the tool that makes the estimate possible. The European Environment Agency calls these functions an essential component in attributing disease burden to air pollution exposure: they are based on epidemiological studies and estimate the increase in risk for a particular health outcome per unit increase of concentration of a certain air pollutant.

A function on its own says nothing about a country. It has to be combined with two other things: a map of the concentrations people were actually exposed to, and population data saying how many people live where. Multiplying the extra risk by the number of people carrying it gives a figure for attributable deaths, or for years of life lost.

Which function is used therefore shapes the answer. The European Environment Agency applies the concentration-response functions for all-cause mortality set out in the World Health Organization's 2021 global air quality guidelines, with cause specific functions detailed in a separate technical report. The uncertainty in the underlying epidemiology travels with the function into every published figure, which is why these numbers are presented as modelled estimates rather than counts.