Ambient air VOC samplers were collected at surface air quality monitoring sites, near sources of interest. HC samplers were collected in electro-polished stainless steel canisters which were returned to laboratories of the selected species by cryogenic pre-concentration GC-FID, following the EPA T014 protocol (Winberry et al., 1988, McClenny et al., 1991 and Doskey et al., 1992). The microenvironment as well as personal monitors were eluted with adequate eluents and then analysed by GC-MS (Ortiz, 2000).