Airborne radioactivity monitors put up in a network as a warning system in case of nuclear accidents were used to gain insight in the temporal variations of 222Rn and its decay products. Average equilibrium equivalent decay product concentrations (EEDCs) over a period of five years for stations across the country range from 1 to 3 Bq.m-3. Hourly averaged concentrations show a diurnal variation at all stations. The amplitude of this variation is maximal in summer and minimal or non-existent in winter. Superimposed is a seasonal variation with a maximum in late autumn and a minimum in spring. Wind velocity appears to be the major variable controlling the variation in EEDC in the outdoor environment of the Netherlands. Humidity seems to be correlated with the EEDC of 222Rn, probably because, due to plateout, a better equilibrium between 222Rn and its decay products is installed. Reduced EEDC during and shortly after rainfall seems to indicate a dilution of 222Rn in ground surface air due to enhanced vertical mixing below the rain cloud.