Sorbent tube sampling, available from Active Environmental Solutions , is the NIOSH/OSHA approved method for collecting hazardous gases and vapours from the air. Federal law has established permissible exposure limits (PELs) for workers' exposures to a variety of airborne chemical hazards. These limits are specified in several ways such as, eight-hour time-weighted averages (TWAs), short-term exposure limits (STELs) and ceiling values. Eight-hour TWA limits are specified for full-shift exposures. STELs are issued as 15 minute exposure limits and ceiling values are issued as peak levels not to be exceeded at any time during the working day. Sorbent tubes have been established as a reliable tool for each of these sampling requirements. Active Environmental Solutions provide a range of sorbent tubes, tube holders, adjustable low flow holders, CPC’s, Protective Tubes Covers, and accessories.