Pilot field study: Carbon monoxide exposure monitoring in the general population

A pilot field study was conducted with nine members of the general public to measure carbon monoxide exposure using personal monitors. The principal study objectives were to design and evaluate the research protocol and the instrumentation performance for application to the conduct of a large-scale personal monitoring program. Integrated carbon monoxide exposure was monitored and recorded according to type of activity such as “commuting” or “at work” for approximately 45 days by each subject. All subjects except one were able to handle both the equipment and data recording requirements with no significant problems. Actual data recording responsibilities consumed less than 10 min daily. The data consisted of 355 person-days each over 6-h duration, and weekdays only, from which 8-h average personal exposure levels could be computed. The 9 ppm (μL/L) ambient air quality standard was exceeded on 22 person-days. Elevated carbon monoxide concentrations during the commuting activity were frequently associated with the exceedences.     

Rapid Screening and Identification of Airborne Carcinogens of Greatest Concern in California

This paper describes a method for establishing a priority list of airborne carcinogens within a state Jurisdiction. In this case it was necessary to identify, from among hundreds of potential candidates, the five to ten materials of greatest potential concern in California as airborne carcinogens.

Because no previous inventory of carcinogens in California existed, published lists, rankings, and assessments of national scope were used to identify candidates. By systematic manipulation and comparison of these data sources, 47 materials of some notoriety were chosen for closer scrutiny. This selection was pared to 22 candidates largely by eliminating those which had very little production and use in California. (Substances primarily used as pesticides were excluded from the scope of this study.) The remaining candidates were then ranked by additive . and multiplicative algorithms and by a panel of experts. The results of these rankings were combined to produce a single selection of 11 priority candidates. In alphabetical order, they are arsenic, asbestos, benzene, cadmium, carbon tetrachloride, chloroform, ethylene dibromide, ethylene dichloride, N-nitrosoamines, perchloroethylene, and polycyclic aromatic hydrocarbons. In continuing studies, a baseline emissions inventory is being prepared, and a source testing program is being designed.     

Carbon monoxide intrusion into sustained-use vehicles

In its evaluation of federal ambient air quality criteria for carbon monoxide (CO), the U.S. Environmental Protection Agency is seeking to identify the mechanisms of CO exposure and the populations at risk. The suitability of existing fixed-site monitoring networks to characterize population exposure is also being studied. This paper describes field measurements in two major metropolitan areas of CO exposure in the passenger sections of 1164 buses, taxis, and police cars. The objectives of the program were to identify high-CO vehicles and to elucidate the mechanisms for high passenger exposures. Vehicle fleets were initially screened with passive dosimeters and pump-driven personal samplers. Selected vehicles were then instrumented with portable electrochemical-cell continuous analyzers coupled to recorders. Principal CO sources and intrusion pathways were pinpointed by use of an inert tracer gas (SF₆) detection system. Intrusion tests were made at idle and with the vehicles in motion. Fixed-station monitoring values were found to underpredict, in a nonuniform manner, out-of-vehicle CO exposures determined by the field measurements. In 58% of the 120 personal sampler readings for rides greater than eight hours, the EPA eight-hour ambient air quality standard for carbon monoxide (9 ppm) was exceeded.