Dr. Cristina Paunescu (from the Faculty of Pharmacy of Paris) and al. published a few days ago, in Indoor Air papers, the results of a large field study for particles pollution measurements. A study very rare in its ambition for statistically relevant data acquisition! A cohort of 96 children, aged 9 and living in Paris and suburbs, was gathered to monitor the ultrafine particles and black carbon they breathed over 24 hours of their everyday life, with portable sensors of scientific quality. The results are revealing : school and home are the places where children are the most exposed.