Annual Variations of Volatile Chlorinated Hydrocarbons in Ambient Air in Industrial Areas in Niigata

Atmospheric concentrations of three volatile chlorinated hydrocarbons (VCHs), 1, 1, 1-trichloroethane (MCF), trichloroethene (TCE) and tetrachloroethene (PCE) were monitored in two industrial areas in Niigata Prefecture during fiscal years 1994 to 1996. Geometric mean concentrations of MCF, TCE and PCE in a metal ware manufacturing area (Tsubame) were 0.28 ppb, 2.7 ppb and 0.046 ppb, respectively; those in a textile and dying industrial area (Tokamachi) were 0.37 ppb, 0.059 ppb and 0.56 ppb, respectively. These concentrations were compared with those from fiscal years 1989/1990 to 1993. Mean concentrations of MCF in these two areas showed downward trend according to decrease of MCF amounts used. Those of TCE and PCE in Tsubame also showed downward trend slightly. On the other hand, mean concentration of TCE showed upward trend since 1992, whereas those of PCE was almost the same as those during 1989 to 1993 in Tokamachi.