Real-Time Health Impact Assessment Of A Major Air Pollution Episode May Underestimate The Problem, March 2014, France

Abstract

Introduction On 6-18 March 2014, a major episode of air pollution (PM10 concentrations exceeding 100 µg/m3 locally for several days) affected almost all France as well as other European countries, with impact in French media and policy-makers. We monitored health impact in France and consulted on actions taken in other countries. Methods From 6 to 25 March 2014, we monitored selected morbidity indicators a priori linked to air pollution using the French syndromic surveillance system SurSaUD® that covers 70% of emergency department visits and almost all doctors' house calls. On May 6, we sent a short questionnaire to 15 international experts asking how their countries/cities assessed the health impacts of such episodes. Results At the national level, no health impact could be detected during and after the episode. However, in the Paris area that faced the highest levels of air pollution, reported emergency department visits for asthma increased with a peak on 20 March (n=152), three times higher than during the reference period. Fourteen of 15 international experts indicated that they assess health impacts of such episodes a posteriori through time series analyses, while one reported real-time syndromic surveillance during the episode. Discussion Even if syndromic surveillance gives timely information on potential local health problems, international experts reported difficulties detecting real-time impact. Dialogue is needed with authorities requesting real-time health impact assessments as waiting for reported health outcome may delay prevention measures. But can the science of epidemiology better meet the authorities' needs?