Both direct emission from fires and ash resuspension from burnt soils could be an important source of airborne PM10. This pyrogenic material, which is composed of organic matter, black carbon and inorganic material, is to a large extent present in the size range below 10 µm and so can be resuspended by wind [17]. Although the contribution to ambient aerosol from fire smoke will generally be episodic, in areas where there is a constant forest burning, the particulate emission from this source could be significant. Each year in Mediterranean countries about 50 000 fires are set (mostly by man) producing between 700 000 to 1 000.
