Human exposure to urban air pollution.

Abstract

This study deals with some methods of making human exposure estimates, aimed at describing the human exposure for selected air pollutants in Sweden that are suspected carcinogens. Nitrogen oxides (NOx) have been chosen as an indicator substance for estimating the concentration of the urban plume. Earlier investigations have shown that the traffic in Swedish cities contributes around 85% to the measured NOx concentrations, and that most of the mutagenicity in urban air originates from traffic. The first section of this paper describes measurements in Stockholm of some unregulated light hydrocarbons, such as ethene, ethyne, propane, propene, butane, and isobutane. In addition, measurements of some volatile aromatic hydrocarbons are presented. Simultaneous measurements of carbon monoxide (CO) were made. The ratios between CO and the individual specific compounds were determined by linear regression analysis. By analysis of relationships between CO and NOx, NOx concentrations can be used as a tracer to describe the exposure for these specific compounds. NOx are considered to be a better tracer than CO, because NOx or NO2 values exist for many places over a long time, while CO is measured mostly in streets with high concentrations. At low concentrations, instruments that measure normal CO levels give no detectable signals. Through use of atmospheric dispersion models and models that describe how people live and work in urban areas it has been possible to describe the average exposure to NOx in cities of different sizes. The exposure to NOx for people living in the countryside has also been estimated. In this way, it has been possible to calculate the average exposure dose for NOx for the Swedish population. This figure is 23 micrograms/m3. By use of the relationships between NOx and specific compounds the average dose has been calculated for the following compounds: polyaromatic compounds (PAH); ethene, propene, and butadiene; benzene, toluene, and xylene; formaldehyde and actaldehyde; nickel, chromium (VI), arsenic, and cadmium; asbestos; and silicon.

Cancer Risk Assessment, Indicators, and Guidelines for Polycyclic Aromatic Hydrocarbons in the Ambient Air

“…In the project "Air Pollution in Urban Areas," investigations concerning particle-bound PAHs were performed from 1984 to 1987 in the Gothenburg area of Sweden (Boström et al 1994; P h e n a n th r e n e A n th r a c e n e F lu o r a n th e n e P y r e n e B e n z (a )a n th r a c e n e C h r y s e n e B (a )P B e n z o (g h i) p e r y le n e B e n z o (b )f lu o r a n th e n e In d e n o (c d )p y r e n e B e n z o (k )f lu o r a n th e n e 1985; Löfroth et al 1990;Steen 1985). However, these invesigations occurred before the introduction of MK1 and catalytic converters in gasoline-driven cars.…”

Future Research Needs Associated with the Assessment of Potential Human Health Risks from Exposure to Toxic Ambient Air Pollutants

“…Some examples of indicator substances are given in Table 2. Carbon monoxide and nitrogen oxides have served as good indicator substances for vehicle emissions (58 (31). Efforts should be undertaken to determine whether a better indicator substance can be identified.…”

On cancer risk estimation of urban air pollution

“…This paper serves as a parallel of the estimations based on epidemiological data presented by Hemminki and Pershagen (1). Both papers use the population-weighted exposure data for Sweden (Table 1), presented by Bostrom et al (2).…”