The Environmental Chemistry Department mainly deals with analyzing the samples from air filters at station A located at the WIPP site. The samples are collected on 47 mm diameter membrane filters with the use of a shrouded probe, commonly referred to as a fixed air sampler or FAS . The FAS filters are normally changed daily however, occasionally more than one sample per day is collected when flow rate on any of the sampler legs drops below 1.8 cfm which requires the filters to be changed. All the analyses of the FAS filters are performed according to methods detailed in CEMRC document-controlled, standard operating procedures.Once the samples are returned to the laboratory, the individual filters are first weighed to determine mass loadings and then, after allowing for the decay of short-lived radon daughters, they are counted for gross alpha or beta