Are we safe inside? Indoor air quality in relation to outdoor concentration of PM10 and PM2.5 and to characteristics of homes

Abstract This study investigates the relationship between concentrations of particulate matter (PM 10 and PM 2.5 ) outdoors and indoors, and evaluates the significance of various factors which may influence levels of particle pollution inside homes. Twenty-four hour measurements of the concentrations of PM 10 and PM 2.5 were carried out in 179 locations in Krakow, simultaneously indoors and outdoors, using personal aerosol monitors. Data about the characteristics of homes where measurements were conducted were collected by a questionnaire. Even though daily average outdoor levels of PM 10 and PM 2.5 were higher than indoor levels (p  10 (r = 0.78, p  2.5 (r = 0.82, p  10 and PM 2.5 outside is accompanied by an increase of indoor concentrations, therefore actions to improve urban air quality will result in improved indoor air quality. In addition, modernization of apartments, especially replacing old windows and changing the heating system would also contribute to the improvement of indoor air quality, and thus quality of life.