Assessment of exposure to atmospheric particles: contribution of individual measurements

Background: There are few studies of individual exposure to atmospheric par ticles, because of the relatively bulky and noisy sampling devices. These p ersonalized measurements, generally associated with micro-environmental mea surements, are aimed at studying the distribution of individual exposure an d identifying its main determinants. Methods: A synopsis of the methods implemented in such studies (populations studied, measurements strategies, questionnaires on time-activity patterns , residences and work place) was detailed. The major results are presented and discussed from an epidemiological point of view. Results: The individual exposure measured with portable devices generally w ere generally found to be higher than the estimations made by combining mic ro-environmental (outdoor and indoor) measurements and data from time-activ ity diaries. The difference between results of these two approaches, known as "personal cloud", remains poorly understood. Correlations between indivi dual measurings and outdoor concentrations are weak; nevertheless, day to d ay variations of these two series of measurements are better related. The m ain determinants of individual exposure to particles are identified but a q uantification of their contribution remains difficult, except for passive s moking. Conclusion: personal measurements cannot be used to estimate particle expos ure in large scale epidemiological studies. This exposure needs to be model ized.