Selective estimation of soot in home dust by EPR spectrometry.

The content of soot in home dust collected from eight different flats or homes situated in different areas of Sofia, Bulgaria, is studied for a period of 14 months by using EPR spectrometry. The results obtained show two different areas in respect to the in-door pollution with soot which in one area is three to five times lower in comparison to the another. The characteristic features of both places are the intensive automotive traffic and central heating in the first part and less intensive automotive traffic but local heating facilities in the second area. These results are fully coinciding with previous studies on the soot content in urban aerosols and strongly suggest that main source of soot in air (in form of aerosols or precipitated as home dust) are the local heating facilities.