Health Impact of the 2003 Heat-Wave in France

Abstract

An unprecedented heat-wave struck France in early August 2003, associated to high levels of air pollution. The meteorological event was accompanied by an excess of mortality that started early and rose quickly. Between August 1st and 20th, the excess of deaths reached 14,802 cases in comparison to the average daily mortality in the 2000 – 2002 period. It represents +60 % of mortality for all causes. The observed excess of mortality first affected the elderly (+70 % for 75 years-old and more), but was also severe for the 45 – 74 year olds (+30 %). In all age groups, females mortality was 15 to 20 % higher than male. Almost the whole country was affected by the excess-mortality, however its intensity varied significantly from one region to another and was at a maximum in Paris and suburbs (+142 %). The excess mortality clearly increased with the duration of extreme temperatures. With regard to the location, the highest mortality rate affected nursing homes where the number of deaths observed was twice the expected number. Following the descriptive studies carried out immediately after the heat-wave, two case-control surveys were carried out. The first study was conducted to identify individual risk factors (way of life, medical history, self sufficiency) and environmental factors (housing) in elderly people living at home. The second one was conducted to identify individual risk factors (autonomy/handicap, medical condition, drug consumption) and environmental risk factors (number and quality of personnel available; facility size and characteristics; prevention plans and therapeutic protocols) for elderly residing in a nursing home. This survey was made in two parts: a “facility case-control study” and an “individual case-control study”. High levels of photochemical air pollution were associated to the heat-wave. A study was conducted to estimate the fraction attributable to ozone in the excess risks of mortality jointly related to temperature and ozone, and also to identify a decrease of expected mortality in the weeks following the heat-wave. In cities having experienced the highest excess risk of mortality (Paris, Lyon) the contribution of ozone was minor relative to temperature; the relative part of this air pollutant was higher but variable in cities where the excess risk of mortality was low. The study did not show a harvesting effect within the three weeks following the heat-wave. The French Heat-Wave National Plan, developed immediately after the 2003 event, includes a Heat Health Watch Warning System operating from 2004 and covering the whole country.