NEW research from the United States has provided more evidence of the link between air pollution and poor health.
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The study followed more than 5000 healthy adults over two years and tracked their cardiovascular health using ultrasounds to measure the build-up of fatty deposits in their arteries.
In general, everyone's arteries became more clogged with time, which is what we expect with ageing, but the decline was worse in those people who lived in more polluted parts of the city.
The research examined the tiny particulate matter air pollution called PM2.5, which is often invisible and odourless.
Its small size means it's easily carried on the wind away from the source, and when it's breathed in it gets deep inside your lung.
The toxic elements within the particles can then enter the blood stream and damage the arterial walls.
Particulate matter pollution is monitored around Newcastle and the Hunter, and the latest annual averages for 2012 show that the worst place was Muswellbrook, with an annual average of 10.0 micrograms per cubic metre, and the best place was Wallsend, with 5.1 micrograms per cubic metre.
The US study found that a reduction of 2.5 micrograms per cubic metre reduced the risk of stroke by 2 per cent.
So if you moved from Muswellbrook to Wallsend, then it's very likely that you would reduce your risk of stroke.
A 2 per cent reduction may not sound like a lot, but because air pollution is difficult to avoid this small reduction applies to very many people.
Is it fair to apply the results of a US study to Australia?
The six US cities were generally dirtier than most Australian cities - the cleanest city in the study was St Paul in Minneapolis, which had an average exposure of 11.9 micrograms per cubic metre, which is dirtier than Muswellbrook.
But the levels of air pollution are far less important than the change in levels, and because there's no safe level of air pollution we know that any improvement in air quality will create health benefits.
The more difficult comparison is the content of the particles, as just looking at particle levels is only half the story.
Particles can be made up of a whole range of things, from relatively harmless contents such as sea spray and earth, to more toxic elements such as dioxins and heavy metals.
The US cities in the study were non-industrial, meaning the major source of particles would be from traffic, whose major contents are carbonaceous materials, which are a byproduct of burning petrol. The concern for the Upper Hunter is the burning of not just petrol but also wood for heating and coal for power. The latest reports on the particulate matter content in Muswellbrook and Singleton show that around half the particle contents in the air were carbonaceous.
Given these results I think we can state that the current particulate levels in the Hunter are damaging to health.
What's the advice for people living in these dirtier areas, should they just move?
We can't simply move everybody and it's very costly to move the polluting industries from their current locations.
But we need to understand that there are currently disparities in health simply based on where you live.
The best way for these disparities to be removed is for governments to take strong action to provide cleaner air for everyone. This might include unpopular measures such as congestion charges or taxing heavily polluting vehicles, or it could include reward measures such as reducing registration fees for electric or hybrid cars.
Adrian Barnett is an associate professor at the Institute of Health and Biomedical Innovation, Queensland University of Technology
