size distribution and chemical composition of indoor and outdoor particles in lab building

Introduction: exposure to toxic components in indoor pm is associated with a wide spectrum of adverse respiratory and cardiovascular health effects. the fine pm pollution in ambient air is currently a major health concern in iran and is driving increasing research interest. due to air pollution in tehran met-ropolitan, it is necessary to study the concentration and size distribution of particles inside and outside the building.materials and methods: hence, for this study, concentration and size distri-bution of particles matter was calculated with diameters of pm≤0.4, pm0.4-0.7, pm0.7-1.1, pm1.1-2.1, pm2.1-3.3, pm3.3-4.7, pm4.7-7, pm7-11, pm≥11 and tsp during two seasons in the lab building in the tehran. measurements on the aerodynamic size of atmospheric aerosols carried with anderson type 1-acfm cascade impactor with six-stage. the length of each collection period was about 24 h. results: the results show that the effect of outdoor air pollution on the con-centration of particles in the indoor environment is significant. according to these results, the lowest value is for particles with a diameter greater than 11 µm. the highest value of this ratio is dedicated to pm≤0.4 and with the increase of the aerodynamic diameter of the particles, the i/o decreases as well. a similar trend was recorded for concentration of tsp. the highest difference in the concentration of tsp in indoor and outdoor was 60.25 and 188.36 µg/m3, respectively.conclusion: this effect is due to factors such as the lack of standard ventila-tion, old doors and windows and the life of the building.