Carbon Monoxide Exposures of Washington Commuters

Abstract

The potential for directly monitoring public exposure to air pollutants has been realized with the development of personal exposure monitors. The microenvironmental approach to exposure assessment involves monitoring the concentrations within microenvironments thought to contribute significantly to a population's total exposure. This paper focuses on the commuting microenvironment, because of the suspected large contribution that commuting makes to the total population exposure to carbon monoxide (CO). In particular, this paper presents typical CO concentrations, to which automobile, bus, and rail commuters of the Washington, D.C. metropolitan area were exposed, on 15 hypothetical routes during winter 1983. In addition, the paper assesses the relative importance of several factors that explain variability in CO levels inside automobiles during rush-hour periods.The study found that automobile commuters were exposed to average CO concentrations that typically ranged from 9 to 14 ppm over trips that typically took between 40 and 60 minutes. Average CO levels for bus commuters typically ranged from 4 to 8 ppm for trips lasting between 90 and 110 minutes, and those for rail commuters typically ranged from 2 to 5 ppm for trips of 30-45 minutes. The most important factors influencing CO concentrations inside automobiles were identified as link-to-iink variability, day-to-day variability, and the interaction between link and commuting period. Variability in CO levels by route, driver, and factors specific to a particular commute were moderately important. Between and within monitor variation were the least important sources of variation in CO levels. Increasing automobile speed from 10 to 60 mph reduced average CO exposure by 35 percent regardless of commuting period. The study suggests that automobile commuters, who begin their homeward trips from highly polluted downtown parking garages, may carry residual garage concentrations with them as they travel along downtown streets.

Urban commuter exposure to particle matter and carbon monoxide inside an automobile

“…The highest CO concentrations are typically observed in dense traffic, when a group of vehicles is accelerating in traffic lights (Colwill and Hickman, 1980). Contrary to Flachsbart et al (1987), Clifford et al (1997) did not find a significant association of the CO levels with vehicle speed. They report considerable day-to-day variation of CO concentration.…”

“…The concentrations of CO and VOCs were higher in the personal samples of car drivers than in personal samples of cyclists (Van Wijnen et al, 1995). Flachsbart et al (1987) observed a relationship between CO level and automobile speed. The average CO level is shown to decrease with increasing speed.…”

“…Personal CO exposures of commuters are usually higher than CO exposure levels in outdoor or indoor microenvironments (Akland et al, 1985). Previous studies in Washington, DC, USA, and in Paris, France, have shown average CO levels for bus commuters 4±8 ppm, for rail and subway commuters 2±5 ppm (Flachsbart et al, 1987), and inside cars 5±14 ppm (Dor et al, 1995). In this study, the invehicle CO exposures were at a lower end (morning runs) or below (afternoon runs) that range, which can be understood by the fact that Kuopio is a small town surrounded by large forested, lake or agricultural rural areas.…”

“…Automobile commuters are exposed to higher concentrations than bus and rail commuters (Flachsbart et al, 1987). The concentrations of CO and VOCs were higher in the personal samples of car drivers than in personal samples of cyclists (Van Wijnen et al, 1995).…”

An Analysis of Household Solid Waste in Kuwait: Magnitude, Type, and Forecasting Models

“…Similar to an approach developed by Flachsbart et al, 13 the variance of solid waste estimated to be due to each socioeconomic factor was expressed as a percentage of the mean household level of solid waste generated per day. The equation had the following form:…”