2425

Background: In order to fight against air pollution and attenuate adverse health effects, many big cities in different countries adopt public policies based on a system of air quality alerts, triggered when air pollution forecasts predict a day with one or more pollutants concentrations beyond the regulatory standars. These programs focus exclusively on reducing emissions on days when air pollution warnings exceed the threshold level and, despite the large investment on this kind of measures, their effectiveness and their benefits on the population health have never been verified. The potential health benefits associated with air quality alert policies implemented in the city of Paris is assessed herein. Methods: Data of daily mortality for non-accidental, cardiovascular and respiratory causes were obtained from the French National Institute of Health and Medical Research for the period going from 2000 to 2015. Data of mean daily PM10 concentrations were collected from the local air quality monitoring networks. A quasi-experimental design was used by combining a propensity-score-matching method with Difference-in-Differences models. The difference in mean daily PM10 concentrations and in daily mortality was compared between eligible and non-eligible days before and after the definition of regulatory standards for PM10 concentrations (2000-2007 versus 2008-2015) and before and after the implementation of lower thresholds values (2008-2011 versus 2012-2015). Results: A significant reduction associated to the implementation of the air quality alerts system in Paris was detected in PM10 concentrations but no evidence was found for an impact on mortality. Conclusions: By capitalizing on natural experiments, this study addresses the question of the pertinence of local public health policies with regard to air quality and health issues and its findings suggest that investing on long-term interventions could be preferable to emergency measures concentrate exclusively on acute-air polluted days.