Atmosphere Theme Report
Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Dr Peter Manins, Environmental Consulting and Research Unit, CSIRO Atmospheric Research, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06746 9
Urban Air Quality (continued)
Exposure to air pollutants [A Indicator 3.10]
The health effects of air pollutants depend on the hazardous nature (if any) of the specific pollutant, and the amount inhaled. The amount of the particular pollutant that a person inhales is known as the dose. This will vary from person to person so that a surrogate measure, the exposure, is used. Exposure is the product of the concentration of an air pollutant and the length of time (duration) associated with the particular concentration.
Emissions of a pollutant and exposure to a pollutant can vary markedly. The sources that produce the greatest quantity of benzene emissions are automobile exhaust and industrial emissions (Figures 84 and 113). The dominant sources contribute only modestly to the exposure of the general population, which faces a considerably greater threat from the benzene released by cigarettes, petrol fumes and consumer products (Figure 113).
Figure 113: Sources of emissions and exposure to benzene in the USA.
Source: Data from Ott and Roberts (1998)
Beer and Walsh (1997) assessed the exposure of Australian urban populations to air pollutants from 1993 to 1995. There is a concentration to which 37% of the population is exposed at least once a year that is characteristic of the city (Figure 114).
Figure 114: Characteristic concentrations of population exposed in Australian urban areas to various pollutants and average times.
Units of characteristic exposure concentration are those stated on the z axis. Bsp = back scattering light coefficient (used to calculate particle concentrations).
Source: Beer and Walsh (1997)
The high values of CO and SO2 for Adelaide, compared with other cities, may reflect unrepresentative siting of air pollution monitoring stations, or may represent particular anomalous years.
Implications
When compared with the results presented in earlier figures, most urban Australians (Figure 114) are not exposed to the maximum values that individual monitoring stations may record. Thus, PM10 concentrations in Sydney can reach maximum values of 60 to 90 g/m3 but the characteristic concentration which typifies the population exposure is only 15 g/m3. Compliance with the Air NEPM is unlikely to alter such exposure because the standards set in the Air NEPM deal with extreme values. Such values, which occur rarely, also tend to be spatially isolated so that they do not affect most of the urban population. Exposures are more likely to be reduced as a result of ADR37/01 taking effect through the vehicle fleet.