X-Ray fluorescence (XRF) is an emission spectroscopic method for the qualitative identification and quantitative determination of elements. With few exceptions, XRF provides no information concerning the chemical species in which the sought element is found. XRF is a technique that offers many advantages for the quantitative determination of the average elemental composition of dust. The most obvious advantage of XRF is the fact that the dust may be analyzed directly on the filter. Cascade impactors have been found to be ill suited for sample collection when XRF is to be used for the analysis. The major sample collection technique used for XRF analysis of airborne dust has been some type of filtration or virtual impactor using filters. One important consideration in selection of a filter for aerosol sample collection is the choice of pore diameter of the filter. To convert the raw X-ray intensity to meaningful analytical results requires several procedures.