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Urban Air Quality (continued)

Findings and implications

The measurements that are summarised above indicate that urban air quality for most Australians has improved and continues to improve.

Over 100 years ago the poet Banjo Patterson wrote:

I am sitting in my dingy little office where a stingy
Ray of sunshine struggles feebly down
between the houses tall,
And the foetid air and gritty
of the dusty, dirty city,
Through the open window floating
spreads its foulness over all.

The inner suburbs of Australian cities are no longer filled with houses, brickworks and power stations, all of which burnt coal for energy and led to the grime and the grit that Banjo Patterson wrote about. This change was partly as a result of air quality action plans that aimed to reduce the emissions of air pollutants and thus ensure that concentrations of the pollutants decline.

The success of such action plans hinged on knowing the source of the air pollutants and tackling their emissions. Improved combustion efficiencies, the use of reduced sulfur fuels, the use of gas as an industrial fuel, increased stack heights and flue gas scrubbing all were important in reducing industrial pollution. The introduction of unleaded petrol and the use of catalytic converters to meet emission standards on cars also reduced automobile pollution (Manins 2000).

Several initiatives will be important in the development of future action plans. These include an improved ability to provide emissions inventories, and to use these inventories in combination with computer models to predict the expected air quality (see Air pollution forecasting) and to verify the predictions with accurate measurements. Existing air quality action plans are based on detailed studies of air quality from the 1980s onwards. These studies used the emissions inventories and observations to verify the accuracy of computer models, and then used the models to estimate the pollutant concentrations in locations where there were no observations, and to test the consequences of alternative emissions.

Our knowledge of ambient air quality is good for certain pollutants in certain locations. Other important components of air quality, such as pollens, are not being regularly and comprehensively measured. Of the criteria pollutants, there is little evidence of urban air pollution problems arising from sulfur dioxide, nitrogen dioxide or lead, and present trends indicate that carbon monoxide is unlikely to be of concern. However, the recent finding of the Melbourne Mortality Study (EPAV 2000b) that both ozone and nitrogen dioxide are correlated with increased mortality, underlines the lack of knowledge of the combined effects of the pollutants. In this context, combined effects are called synergistic effects. Thus, monitoring of all of these pollutants needs to continue, as it will because of the reporting requirements of the Air NEPM.

Episodes of high ozone concentration continue to occur in Sydney and Melbourne. As older motor vehicles are phased out and replaced by newer vehicles subject to more stringent emission controls as well as 'inspection and maintenance' programs that ensure compliance with emission limits, high ozone episodes should become more infrequent. The concern is that as vehicle numbers continue to rise, the sheer quantity of emissions may again lead to ozone episodes. The planned introduction of Euro3 and Euro4 controls will diminish such episodes, although eventually the growth in vehicle numbers and vehicle kilometres travelled could again raise the total emission levels. Maintaining and improving urban air quality will require adherence to strict emission standards. New standards to address issues such as particulate emissions are available for diesel vehicles. Measures to reduce particulate emissions from cars will also be needed. The National In-Service Vehicle Emissions Study (FORS 1996) showed that regular inspection and maintenance of vehicles can produce substantial reductions in pollution.

Particles are of concern as a result of woodsmoke in Canberra, Launceston and some other regional centres such as Armidale, NSW. They are probably also of concern in other urban locations in the country and at the urban-rural interface in the cities (see the Human Settlements Theme Report). There are insufficient data from other urban areas but the nephelometer data that are available show that particles are of episodic concern.

Knowledge of the air quality indoors, at home, in the workplace, in cars and in other transport vehicles, is not as good. Australians spend from 90 to 96% of their time indoors (ABS 1994, 1996a, 1998), so further information is needed about the pollutants to which people are exposed (see also the Human Settlements Report). More data could be collected through the use of lightweight, relatively cheap monitors that could be worn to measure personal exposure to certain atmospheric pollutants (see http://www.csiro.au/promos/ozadvances/series1air.html ).

There are two major categories regarding health effects of air pollutants:

1. Pollutants for which it is possible to find a 'safe threshold' or the 'No Observed (Adverse) Effect Level': an air quality standard set below this level should be completely protective of human health.
2. Pollutants for which scientific results indicate that there is no safe exposure (e.g. nitrogen dioxide, particles PM10 and PM2.5, and carcinogens. Emphasis has to be given to reducing exposure to these pollutants. Most air toxics, such as benzene, are in this category.

For pollutants in the second category EPA Victoria (EPAV 1999c) has ranked such air pollutants on the basis of four criteria: carcinogenicity, other effects of long-term exposure, effects of short-term exposure, and environmental effects. In the EPAV (1999c) list of priority hazardous air pollutants (Table 29), the score is determined on the basis of these four criteria. More information on the air toxics, and on indoor air quality, may be found in Environment Australia (2000b) at http://www.environment.gov.au/airtoxics.

Once the results of the present generation of air quality action plans are acted on, then there will be few, if any, exceedences of the criteria pollutants that are regulated in NEPM standards. Therefore, future attention (e.g. for development of an air toxics NEPM) will be devoted to the hazardous air pollutants (Table 29).

Table 29: List of priority hazardous air pollutants

Air pollutant	Score	Health effects
Benzene	9	Carcinogenic, causes anaemia
1,3-Butadiene	8	Carcinogen
Polycyclic aromatic hydrocarbons (PAH)	8	Carcinogen, environmentally persistent
Arsenic and compounds	8	Carcinogen, environmentally persistent
Chromium and compounds	8	Carcinogen, affects respiratory system, inhalation can damage nose, throat, lungs, stomach and intestines, environmentally persistent. May lead to asthma, other allergic reactions, stomach upsets, ulcers, convulsions and kidney damage
Nickel and compounds	8	Carcinogen, can affect the respiratory system, environmentally persistent
Cadmium and compoundsA	7	Carcinogen linked to prostate and kidney cancer in humans and also to lung and testicular cancer in animals. Smoke from burning cadmium or cadmium oxide can, in severe cases, affect respiratory system, environmentally persistent
Dioxins and furans	7	Carcinogen, skin disease, environmentally persistent and bioaccumulates
Mercury	7	Can cause reproductive problems, environmentally persistent, bioaccumulates
Dichloromethane	5	Probable carcinogen, moderately persistent in the environment. High concentrations may cause unconsciousness and death. Exposure may irritate lungs, cause pulmonary oedema and irregular heartbeat. Long-term exposures at high level may damage the liver and brain
Formaldehyde	5	Carcinogen, irritates the skin, eye and respiratory system, and can exacerbate asthma
Styrene	5	Possible carcinogen
1,4-Dichlorobenzene	3	Probable carcinogen, moderately persistent in the environment
Tetrachloroethylene	3	Probable carcinogen
Manganese compounds	3	Can affect brain function, moderately persistent in the environment

^A The score for cadmium may be an overestimate (EPAV 1999c). A higher score indicates a more serious concern.

Source: after EPAV (1999c).

Motor vehicles are the most persistent threat to Australian urban air quality. In 1971, an Australian population of 13.07 million people drove 3 997 000 passenger cars (1 car for every 3.3 persons). By 1998, the number of passenger cars had risen to 8 629 000, or one car for every two persons. Estimates (BTCE 1996) are that by 2015 there will be over 11 million passenger cars on the road, although per person car ownership will have reached a plateau.

Beer (1995) showed that the emissions from a growing vehicle fleet will eventually counteract the beneficial effects of the present generation of three way catalytic converters that provide emission controls on passenger cars. There are four ways to tackle the problem.

Supply-side changes

Supply-side strategies might be based, for example, on improved engine efficiencies, provision of better road or public transport networks, and Intelligent Transport Systems (ITS) to make road systems more efficient. Australia was a pioneer in developing ITS with the Sydney Coordinated Adaptive Traffic Control System (SCATS), which is now widely used in other countries (Austroads 1999).

Demand-side changes

Demand-side strategies involve changes in the behaviour of those involved in the transport sector, either as users or suppliers of services. Such changes may involve measures to encourage modal shifts (commuter use of public transport, rail haulage of freight instead of road haulage), telecommunications and e-commerce to reduce the need for journeys. Examples include the work of SmogBuster, LGA actions, EPA Victoria Neighbourhood Environment Improvement Plans, and the actions specified in state transport plans.

Fuel switching

Fuel switching is the most straightforward means of air pollutant reduction in the transport sector. It has been used internationally (e.g. the decision of the Hong Kong government for the mandatory conversion of the taxi fleet to LPG). Beer et al. (2000) examined the emissions from standard and alternative fuels. There are significant new developments in this area, such as the new Fuel Quality Standards and Euro fuel standards, and low volatility summer petrol in different States. Low emission hybrid electric vehicles are being introduced in other countries and Honda intends to introduce such a vehicle to Australia. The Toyota Prius has been available in Japan and the USA since 1998. Daimler-Chrysler intends to introduce zero emission vehicles with the first fuel cell buses in 2002 and the first fuel cell cars in 2004. Despite these initiatives, and the existence of demonstration versions and concept versions of hybrid vehicles, in the year 2000 they were not yet on sale in Australia.

Pollutant capture

The use of various forms of pollution control equipment (e.g. catalytic converters and particulate traps) need to be combined with an inspection and maintenance program to ensure that the pollution control equipment continues to work as intended. In most cases, advanced pollution standards also need low sulfur fuel so that the engine technology, the fuel standards, the pollution control equipment and the inspection and maintenance program need to form an integrated package of measures.

Because of the continued epidemiological evidence that links particles and mortality, there is continued pressure to reduce the emissions of pollutants. The passage of the National Fuel Quality Standards Act 2000 means that diesel fuel will be low sulfur, and thus it will become realistic to expect heavy vehicles to install particulate traps and meet Euro3 limits (PM10 emission 0.0583 g/MJ on a transient cycle) on particulate emissions. Similar controls will also need to be introduced on cars.

Assessment of information gaps

During the preparation of this part of the Report, several gaps in the data became apparent. In some cases there were gaps because the data existed, but it had not been processed by the appropriate state environmental authorities and made available as either a Report, or on the Web. Even when this was not the case, most authorities often stressed the uncertainties associated with the data and were reluctant to agree to their processing and dissemination (e.g. data associated with road dust emissions of particulate matter in Figure 84).

The data associated with road dust emissions highlights our lack of knowledge in relation to the sources of exposure to particulate matter. NEPC (1998) ascribes 2400 Australian deaths per year to particulate matter. It is suspected that many of these are as a result of transport emissions but the uncertainties related to the emissions, and the even greater uncertainties associated with the population's exposure to these emissions, mean that we cannot be sure.

Some of the particulate matter emitted from motor vehicles consists of air toxics. Benzene is the most measured, yet even for benzene there is little systematic long-term monitoring. Regular, systematic monitoring of air toxics appears overdue and we expect this issue to be addressed in a forthcoming air toxics NEPM. The health effects from air toxics are long-term, and because many of the air toxics exist as small particles, the existing Air NEPM standards for PM10 will need to be supplemented with PM2.5 standards, both for short-term and for long-term exposure.

The National Pollutant Inventory carries caveats and to date has been less useful than hoped. It will, presumably, be improved.

We have already noted that pollens are not being regularly and comprehensively measured. Nor is indoor air quality.

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