Accordingly, for the purpose of impact assessment, it was decided not to use response functions from daily mortality time-series studies to estimate the excess annual mortality but the change in the long-term mortality rates associated with ambient air pollution. 5 Contrary to the exposure function which is assumed to be the same for all countries, the health outcome frequency (frequency with which a health outcome appears in the population for a defined time span) may differ across countries. These differences may result from a different age structure or from other factors (. drinking and eating habits, different health care systems in the three countries, etc.). Therefore.
