The relationship of atmospheric pollutants and meteorological variables for the Sofia region, Bulgaria

The research on the relationship between meteorological conditions and atmospheric air pollution in Sofia city was conducted based on 1-hour data on meteorological variables (air temperature, global solar radiation, wind speed) and atmospheric pollutants (NO2, CO, O3, SO2, PM10) for 2012-2016. As a result of the correlation and regression analysis of the influence of meteorological variables on the daily concentrations of atmospheric pollutants, the strongest effect is expressed in ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2) and particulate matter (PM10). In urban areas, air temperature (AT), the intensity of global solar radiation (GSR) and, wind speed (WS) have a stronger impact on the concentration of pollutants. There is a strong correlation between air temperature (r = 0.53 ÷ 0.76) and solar radiation (r = 0.65 ÷ 0.77) with ozone concentrations. An exception is the area of Orlov most, where there is an average correlation with temperature and a minor correlation with solar radiation. In regions (except Kopitoto) there are average correlations between air temperature and PM10, SO2, and CO (r = 0.55 ÷ 0.62). There is a weak correlation between NO2 and air temperature and solar radiation in the areas of Druzhba and Nadezhda.