Relationship between ozone and temperature during the 2003 heat wave in France: consequences for health data analysis

Multivariate analyses were used to identify associated climate and ozone pollution profiles. This descriptive method is of great value to highlight the complexity of interactions between these parameters.Ozone concentration and temperature were strongly correlated, but the health impact of ozone pollution alone will be evaluated by focusing on situations characterized by ozone concentrations above 110 μg/m3/8h (air quality guidelines to protect human health defined by the French legislation) and temperatures lower than 26°C, below the discomfort threshold.The precise relationship between ambient ozone concentration and temperature identified during the PAPRICA 2003 study period will be used in analysing the PAPRICA health data.In Europe, the public must be informed when ozone concentrations reach a threshold of 180 μg/m3/h (the concept of threshold means in this context the value above which an information is given). This strategy of information is justified by many epidemiological studies which have reported that high levels of ozone in the air are associated with an increase in acute mortality [1-3] and morbidity [4-6].Other studies suggest that ozone concentrations can have harmful effects on health at even lower levels when they last for several days [7-9]. In France, the objectives of air quality control are to maintain ozone concentrations less than 110 μg/m3 averaged over 8 hours. In the Centre Region of France, these ozone levels are reached or exceeded on average 60 days per year between April and September, but the public does not receive specific information.Within this framework, the network of public health research, PAPRICA, was created in 2002. This network brings together various partners of the Centre Region concerned with air pollution and its impact on health and engaged in research into the effect of ozone on health. Modelling software was used in the Centre Region to predict 24 hours in advance when ozone would exceed 110 μg/m3 for 8 hours. A gr