The aim of this paper was to determine the concentration variability of gaseous effluents (NO2 and SO2) and of particulate matter pollution (PM10) depending on precipitation, and also an attempt at finding an empirical relationship of particulate matter (PM10) washing out effectiveness with precipitation intensity, duration and rate. Washing out effectiveness ΔS was calculated as particulate matter concentration decrease caused by precipitation, expressed as percentage of PM10 concentration before precipitation occurrence. In this paper mean daily and mean hourly values of gaseous effluents (NO2 and SO2) concentration and of particulate matter (PM10) concentration were used, previously recorded at the air quality monitoring station Ursynow from 2004 to 2007, as well as daily and hourly precipitation rates from the station MzWarszSGGW which belongs to the Chair of Meteorology and Climatology of Warsaw University of Life Sciences. The results shown in the paper generally confirm a favourable role of precipitation in decreasing the atmosphere pollution – especially particulate matter (PM10). The resulting determination coefficients should be regarded mainly as statistical indicators of precipitation role which certainly do not determine its quantitative effectiveness. The analysis concerning the empirical relationship of particulate matter (PM10) wash-ing out with precipitation intensity, duration and rate indicated that there existed a weak, statistically significant correlation of the effectiveness of particulate matter removal from the air with both the duration of precipitation as well as precipitation rate, and the resulting formula, in the form of linear function, explains about 10% of ΔS variability.