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)
Indicators of the condition of air quality (continued)
Urban pollen levels [A Indicator 3.9]
European settlement has significantly changed Australian vegetation. Much of the native bush has been cleared (see the Land Report). Today, plants originating from Europe and America are still popular replacements because of their economic and aesthetic appeal. This has heralded important changes in both the amount and the types of pollen distributed in the air. Unfortunately, these changes have had an unforeseen effect on humans.
Australia has now become the 'hay fever capital' of the world (Figure 111) with over 40% of young adults suffering the symptoms of a runny nose and itchy eyes. In Melbourne, this mainly occurs on warm days in spring and early summer when strong winds from the north or west increase the amount of grass pollen to more than 50 grains/m3 of air that is breathed. Levels of 600 grass pollen grains/m3 of air occur in very wet years. Pollen from ryegrass is the main culprit identified in causing hay fever. Ryegrass produces over 0.5 t/ha of pollen particularly laden with the types of proteins that cause allergic responses in susceptible people. Ryegrass is found in lawns and turf used in home gardens, roadside verges, parks, sporting fields and tracks. Pollen from a range of other grasses, weeds and trees also contributes to allergic reactions. In addition, non-pollen causes, such as fungal spores and house dust mites may also cause such reactions.
Figure 111: Percentage of people aged 20 to 44 years who suffer hay fever and nasal allergies.
Despite the importance of pollen counts as an indicator of the health of susceptible Australians, there is little regular, ongoing, monitoring of pollen counts outside Melbourne. There have been a few short-term studies (e.g. Rutherford et al. 1997). The School of Botany of the University of Melbourne (Ong et al. 1995) in association with Asthma Victoria undertakes regular monitoring during Melbourne's peak allergy period from 31 October to 31 January. This is in marked contrast to the USA where local pollen counts for the whole country are readily available via the Internet, at numerous sites including that of the Weather channel (http://www.weather.com/outlook/health/allergies ).
Many complaints received by environmental agencies are because of offensive odour. Figure 112 plots the number of odour complaints received by the Victorian EPA and by the Queensland EPA, as well as the percentage of total complaints that relate to odour in Queensland. Over that whole State, 16 to 26% of total complaints related to odour, although in Brisbane in 1998, a single odour source led to 69% of complaints being related to odour.
Figure 112: Number of odour complaints in Victoria and Queensland and percentage of total complaints in Queensland related to odour, 1998 to 2000.
Source: data from Qld EPA and EPA Victoria whose statistics are based on a financial year
Odours can come from a variety of sources. The most common are rendering plants, waste disposal facilitates, food processing plants and chemical and petrochemical industries. Although emissions from chimney stacks may cause odour, diffuse sources within plants (e.g. leakages from plant and equipment and open vats) normally account for a much larger proportion of industrial odours.
Although odours from industrial stacks can be controlled by means such as afterburners and scrubbers, which either burn or remove the offensive gases from the stack emissions, odours from diffuse sources are often difficult to pinpoint and control.
Many odour problems are the result of poor past planning, which allowed industrial and residential areas to develop in close proximity. Environmental agencies have developed buffer distance guidelines to minimise such problems. These guidelines set out the recommended distances needed between industrial and residential areas to reduce the likelihood of odours from industry or other odour sources affecting nearby residences.