The EuroLifeNet Study: How Different Microenvironments Influence Personal Exposure to PM 2.5 among High-School Students in Milan

Background: Epidemiological studies show that long-term exposure to PM is associated with an increased risk of cancer. The EuroLifeNet study measured the personal exposure to PM2.5 in 90 pupils attending three schools in Milan, using a portable nephelometer, over a three-week period spanning November and December 2006. Background levels explained 40% of the variability of the exposure. Methods: As a second part of that study we analyzed the role of different microenvi- ronments as determinants of personal exposure to PM2.5. Results: Exposure was influenced by the time of day, zone of the city and different microenvironments. Exposure was higher indoors than out, and indoors it was higher in the kitchen, particularly during cooking. In outdoor environ- ments exposure was higher at bus stops where road traffic was heavy. Conclusions: Even though background concentration can be a good predictor of personal exposure to PM, students' personal exposure is strongly influenced by different microenvironments and should be considered in pop- ulation studies. The EuroLifeNet experience gives a contribution to personal exposure measure methodology.