Clinicians prescribing exercise: is air pollution a hazard?

To the Editor: Health professionals in the Sydney Greater Metropolitan Region have been found to be less aware of air pollution and its health effects than are patients susceptible to such effects.1 Therefore Sharman’s brief review of the harmful effects of air pollution is welcome.2

In offering advice on how to minimise the exacerbation of pollution-induced harm by exercise, Sharman concentrates on the spatial distribution and temporal variation of traffic. The advice is sound for the metropolitan population, but incomplete for non-metropolitan residents exposed to smoke from burning biomass.

Australia’s National Environment Protection Measure defines limits for inhalable particulate matter suspended in ambient air (PM10). The NSW Department of Environment and Conservation operates a network of monitoring stations to measure PM10 and other pollutants, and posts the results daily on its Internet site <www.epa.nsw.gov.au/index.htm>. The National Environment Protection Measure requires environmental authorities to work towards reducing the number of days on which PM10 exceeds the daily limit to no more than 5 days per year. This goal is far from being realised in some places.

One such place is Wagga Wagga, NSW, where monitoring of PM10 started on 11 April 2001. From that date up to 6 July 2005, the city experienced 118 days on which PM10 exceeded the limit, as well as many days of pollution near but below the limit. In the same period, monitoring stations in the Sydney Greater Metropolitan Region registered between 11 and 33 days of excess PM10.

Of the 118 days of above-limit PM10 in Wagga Wagga, 30 occurred in the period from 30 October 2002 to 26 January 2003, when there were severe bushfires in south-eastern Australia. Most of the rest had a cause that is very evident in the surrounding countryside in autumn — the burning of paddocks to prepare them for sowing.

Rural residents’ health is worse than urban residents’ health for many reasons, but biomass burning is not widely recognised as one of them. The Australian Medical Association’s Rural Reference Group, which is being convened to improve rural health,3 may wish to add environmental health to its agenda.

There are two steps that the Group could take to lessen the effects of smoke from burning biomass. The first is to acquaint rural doctors with information such as that presented by Sharman. The second is to persuade the Department of Environment and Conservation and NSW Health to issue rural health warnings based on the continuous, real-time output of PM10 monitors in regional centres.