Study of the submicronic particle pollution at a French urban site
Résumé
The French community involved in air quality monitoring early got interested in the measurement of submicronic particles. Since 2003, INERIS has carried out monitoring campaigns once or twice a year in an urban site located near Paris, enabling the constitution of a large hourly database. Besides particle number concentrations and size distribution measured by SMPS/APS, other variables have been introduced into the database: mass concentrations of several pollutants; traffic emissions computed by AIRPARIF from real-time traffic counts; measured or modelled meteorological variables. Since 2009, particle number concentration data have also been provided by 3031 measurements. An exploratory study of the data collected from 2003 to 2007, which focused on particles with diameter in the 10 nm to 500 nm range, was performed in 2008-2009 and presented at the EFCA 2009 symposium. The aim was to gain better insight into the number concentration and size of submicronic particles and better understanding of the sources and processes at stake in an urban environment. A synthetic scheme explaining the daily evolution of submicronic particle concentrations as a function of emissions and meteorology was established. More recently, following the EFCA symposium, investigations have been carried out thanks to additional monitoring campaigns and the enlargement of the summer database, previously limited to three weeks of measurements. Particle number concentrations over those three weeks appeared to be significantly higher than those measured in winter and revealed enhanced photochemical activity. Two recent campaigns of 7 to 11 weeks provided values inferior to winter concentrations, which is in better agreement with data from other European studies. The specificity of the summer season is still confirmed, with a photochemical signal in the early afternoon preceding the ozone peak. In addition to those results, a feedback about 3031 monitoring is presented.