PM₁₀ concentrations (in relation to main gaseous pollutant levels and prevailing meteorological conditions) and carbon isotopic composition of atmospheric CO₂ have been analysed in two health resorts in SW Poland (Cieplice and Czerniawa) to determine the main air pollution sources. In Cieplice, PM₁₀ concentrations followed the variations in NO₂ and CO, as well as SO₂, suggesting traffic and domestic heating to be the main sources of aerosol particles. Conversely, in Czerniawa periodically pollutant rich air masses originating from regional sources contribute to increases in SO₂ and NO₂ levels, whereas the PM₁₀ concentrations are at the background level. The analyzed δ¹³C(CO₂) values reinforced the conclusions drawn on the basis of traditional methods and indicated the different impact of pollution sources between the investigated regions. Czerniawa was controlled by regional sources of CO₂, whereas Cieplice was dominated by multiple local sources of pollutants (mainly traffic pollutants).