Carbon monoxide in the Los Angeles music center garage

Includes bibliographical references (pages 61-63)Sampling was conducted at the Los Angeles Music Center parking garage for carbon monoxide (CO) on five days during August 1973. The sampling device was the Ecolyzer, a portable electrochemical analyzer. Readings for CO within the garage were mostly below 50 parts per million (ppm), but at times of peak usage, especially before and after show times, greatly exceeded this value. Greatest concentrations (including the maximum for the survey of 158 ppm) occurred at the mid levels of the garage, those levels being furthest from sources of incoming ventilation. Concentration patterns from sampled periods were pieced together to model possible concentrations on days of highest usage. A computer program of the Coburn equation used these models to compute predictions of worker carboxyhemoglobin (COHb) blood saturations. Maximums were 6.4% COHb for matinee days, 4. 3% for nights following matinees, and 4. 4% for Monday day shifts. The Ecolyzer was found to drift greatly in association with high temperatures combined with very low humidities. Over a period of two days response drifted downward 33% as variations occurred in temperature and relative humidity. With proper warm-up under moderate temperatures, correlation of Ecolyzer reading with certified gas concentrations for five data points had a coefficient of .996. While portability is an asset of this instrument,continuous running without access to AC outlets is restricted to less than three hours. According to the programs run, reduction of concentrations through increased ventilation must be by at least 1/4 to reduce all worker blood saturations to below 5%, the occupational limit for eight hours set by the National Institute for Occupational Safety and Health (NIOSH). It is recommended that predictions of excessive COHb blood saturations be verified by subjective tests, i.e, either rebreathing or blood tests