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)
The standards in the NEPM for Ambient Air Quality (Table 18) refer only to a group of six non-carcinogenic pollutants, known as criteria pollutants. The standards were set in line with the NEPM goal for the adequate protection of human health and wellbeing and mark the first time that Australia generated uniform air quality standards nationwide.
|Pollutant||Averaging period||Maximum concentration (based on arithmetic means)||Maximum allowable exceedences A (days per year)|
|Carbon monoxide||8 h||9.0 ppm||1|
|Nitrogen dioxide||1 h
|Sulfur dioxide||1 h
|Lead (as TSPs)||1 y||0.5 g/m3||0|
|Particles (as PM10)||1 d||50 g/m3||5|
A Goal to be achieved by 2008.
Source: NEPC (1998).
The World Health Organization (WHO 1999) produced European air quality guidelines for criteria pollutants, and for non-criteria pollutants for which there are no NEPM standards. Air quality standards for cancer-causing pollutants are more problematic, as expressed in this quotation from the (UK) Expert Panel on Air Quality Standards (1994):
The Panel accept that benzene is a genotoxic carcinogen and that therefore no absolutely safe exposure level can be defined. Nevertheless, for practical purposes we believe that a concentration may be proposed at which the risks are exceedingly small and unlikely to be detectable by any practical method. We thus have taken the view that an air quality standard can be set.
It took six years of deliberation before the recommendation of the Expert Panel, for a 5 ppb annual average standard, was officially introduced with a requirement to be met by the year 2003. On 2 December 1998, the European Commission (1998) proposed a much stricter annual air quality goal of 5 g/m3 (1.5 ppb) for benzene. This goal is to be met by 1 January 2010. Other authorities have been more reluctant to set standards for air pollutants that are suspected to cause cancer, and such pollutants are absent from the WHO list.
Air pollution control authorities have found it useful, when presenting air quality information to the public, to use an air quality index (or an air pollution index) as a means of combining information about a range of the pollutants. Expressing air quality as an index makes it easier to compare pollutant levels and air quality at different monitoring stations at a glance.
The New South Wales EPA calculates a regional pollution index (RPI) (see http://www.epa.nsw.gov.au/air/rpi.htm and http://www.epa.nsw.gov.au/soe/direct/desc/rpi.html ). At these sites, graphs of past values of the RPI, such as those shown in Figure 89, are available. The Pollution Indexes are based on measured concentrations of visibility, fine particles, ozone and nitrogen dioxide in the lower atmosphere. Each variable is compared to the Air NEPM Standard, and a value equal to the NEPM standard is taken as 50. The pollution index is the highest of the values.
Figure 89: Values of the Sydney morning air pollution index for January and February 2000.
Values above 50 are deemed highly polluted. Values above 25 indicate medium-level pollution.