摘要：Concentrations of four volatile chlorinated hydrocarbons (VCHs), i.e. 1, 1, 1-trichloroethane (MCF), trichloroethylene (TCE), tetrachloroethylene (PCE) and tetrachloromethane (PCM), in the ambient air at a rural site and four industrial sites were monitored. One week measurements of the VCHs were carried out in recent 3 years (April, 1989 to March, 1992). Mean concentrations at all sites of MCF, TCE, PCE and PCM were 1.3 ppb (0.25 to 3.2 ppb), 0.97 ppb (0.053 to 4.6 ppb), 0.29 ppb (0.039 to 0.84 ppb) and 0.12 ppb (0.097 to 0.24 ppb), respectively. The concentration of VCH used at the industrial site was most elevated compared with the other sites. PCM concentrations at all sites except that located near chemical plants were close to the background concentrations. MCF, TCE and PCE concentrations at the rural site were higher in winter season than in summer season ; this seems to be caused by meteorological factors. Some of those at the industrial sites showed individual variations, caused by both meteorological factors and operation condition of the industry.
