The LBNL/QGI occupational carbon monoxide (CO) dosimeter (LOCD), a new, ine
xpensive CO passive sampler, was field-validated in an occupational exposur
e assessment study in the Moscone Convention Center (MCC) in San Francisco,
CA in January, 1997. The LOCD measures time-weighed-average (TWA) CO expos
ures from 10 to 800 parts per million hours (ppm h; accuracy +/-20%; precis
ion 10 ppm h). This device represents a major improvement over currently av
ailable low-cost personal CO monitors. At the MCC, over 1000 workers set up
and remove exhibitions. Forty propane-powered forklifts moved materials th
roughout the 42 000 m(2) of exhibit halls. Diesel truck emissions enter the
building via three internal underground loading docks. The LOCD was used t
o 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 h
ighest exposures (maximum = 34 ppm) with GM (GSD) of 9 ( 1.7) and 9 ( 1.6)
ppm, respectively. Attendants and Installer/Decorators had the lowest expos
ures with GMs of 6 (1.6) and 7 (1.4), respectively. The Cal/OSHA personal e
xposure limit for CO is 25 ppm time-weighted average (TWA).