place when the OSHA PEL for chlorine was a Ceiling value (15-min samples were taken). Although long-term samples were only taken during breakthrough studies, the data appears to indicate the method is capable of taking samples for chlorine TWA assessments. Two 4-h samples are recommended for TWA determinations of chlorine. When considering the amount of chlorine collected (as mass), any samples taken near the TWA PEL of 0.5 ppm will have slightly larger mass concentrations of chlorine than those tested for this evaluation. In addition, during the evaluation no breakthrough was noted after 240 minutes of sampling and collection efficiency was excellent after 15 minutes of sampling. Both of these experiments were conducted at approximately 4 times the TWA PEL of 0.5 ppm....
