There is an extensive documentation in Europe and North America about the short term effects of air pollution (especially particulate pollution) on health and a general consensus about their order of magnitude.¹ In contrast, long term effects, which are potentially very important, have been addressed in only a few cohort studies. This is mainly due to the problems of designing and executing large and expensive studies of long duration. Three studies have reported results from the USA,^2–4 and only one from a Dutch cohort in Europe.⁵ In this issue, results from another European cohort study performed in France are reported.⁶

The long term effects of particulate air pollution reported so far, exceed those of short term exposures and have a larger impact in terms of years of life lost.^7,8 The effect estimates from cohort studies, especially the ACS study,³ have been applied in various health impact assessment (HIA) …