years of life lost

A measure of early death counting the years people would statistically have lived had they not died young, rather than counting the deaths themselves.

A death count treats every death alike. Years of life lost does not. The European Environment Agency defines it as an estimate of the average number of additional years that people in a population could have statistically lived if they had not died before reaching a certain statistical life expectancy. A death at 40 therefore contributes many more years of life lost than a death at 85, so the measure answers how much life a risk factor takes away rather than how many people it kills.

The practical value is comparison. Expressed per 100,000 inhabitants, years of life lost lets countries of very different sizes sit beside each other. That is how the agency can show that the heaviest relative burden of air pollution in Europe falls on eastern and south-eastern countries, a pattern the raw death counts hide because those are dominated by the largest populations. For fine particles in the EU in 2023 the agency put the total at 1,914,000 years of life lost, alongside 655,000 for ozone and 351,000 for nitrogen dioxide.

The figure depends on the life expectancy chosen as the reference point, so years of life lost from different studies are comparable only when they share that assumption.

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