[Inside and outside particulate pollution of a locality]. / Pollution particulaire a l'intérieur et à l'extéreur d'un local

The present study of the suspended matter concentration within and outside premises has shown: that inside premises, the filtrating effect of the walls during non-occupation periods (week-end) is apparent, thus the inside concentration remains below the outside concentration; that during the hours and the days when the premises are occupied, the inside concentration is significantly above the outside concentration; that the increase in concentration may be expressed by an "occupation index" depending on the number of people within the premises; that chemical composition and grain size spectrum undergo changes which seem to indicate the appearance of less acid particles which contain more ammonia and nitrates and less SO4, Ca, Fe and Pb than those to be found outside. These particles seem to originate from condensation and recent abrasion. This final point of the conclusions, based on preliminary experimental evidence, has not the pretention to be definite.