Estimation and control of atmospheric emissions of chloroform and dichloromethane due to laboratory activity

In Japanese universities, the management of chemical reagents has become an important issue in preserving the environment and the health of students and researchers. It is thus necessary to estimate the levels of chemical emissions into the environment and to measure working-environment chemical levels in laboratories. However, there are many laboratories in universities using many chemical reagents for their own needs. Hence, it is difficult for universities to quantitate the amount of chemicals on campus, and there is a lack of information about laboratory environment chemical levels. In this study, the material balance of chloroform and dichloromethane (DCM) in Kyoto University was examined, and the emission rates of chloroform and DCM were estimated to be 37-50% and 50-70%, respectively. These chemicals were thought to be volatilized mainly through reduced-pressure distillation. However, it was found that there was a loss of chemicals due to volatility, which researchers were unaware of, such as that during solvent recovery under reduced pressure and volatilization from containers of organic waste liquid. On the other hand, working-environment chemical levels were measured in several laboratories which used chloroform and DCM frequently. Even in such laboratories, the average concentrations of these chemicals were approximately 1 ppm at most measurement points.