A New Carbon Monoxide Occupational Dosimeter: Results from a Worker Exposure Assessment Survey

The LBNL/QGI occupational carbon monoxide (CO) dosimeter (LOCD), a new, inexpensive CO passive sampler, was field-validated in an occupational exposure assessment study in the Moscone Convention Center (MCC) in San Francisco, CA in January, 1997. The LOCD measures time-weighed-average (TWA) CO exposures from 10 to 800 parts per million hours (ppm h; accuracy +/- 20%; precision 10 ppm h). This device represents a major improvement over currently available low-cost personal CO monitors. At the MCC, over 1000 workers set up and remove exhibitions. Forty propane-powered forklifts moved materials throughout the 42,000 m² of exhibit halls. Diesel truck emissions enter the building via three internal underground loading docks. The LOCD was used to measure 154 worker exposures on 3 days. Sampler performance was compared to a standard method at 15 fixed sites. The geometric mean (GM) of all 154 exposures was 7 ppm (geometric standard deviation (GSD) = 1.6); 10% of the exposures was 10 ppm or more. Dock Walkers and Forklift Operators had the highest exposures (maximum = 34 ppm) with GM (GSD) of 9 (1.7) and 9 (1.6) ppm, respectively. Attendants and Installer/Decorators had the lowest exposures with GMs of 6 (1.6) and 7 (1.4), respectively. The Cal/OSHA personal exposure limit for CO is 25 ppm time-weighted average (TWA).