As far as urban centres go, Australia’s have some of the best quality air in the world. It’s just as well, because poor urban air quality is a significant health hazard.
These are among the key findings from the State of the Environment 2016 report, released today.
“Air quality is generally quite good in Australia’s cities, they benefit from being quite spread out from one another,” says Dr Kathryn Emmerson, an atmospheric chemist at CSIRO and one of the authors of the Atmosphere chapter of the report.
“Unlike in places like Europe or Asia, air pollution from one Australian city doesn’t tend to impact on the other cities because of the distance between them.”
Although the overall air quality picture is quite good, Australia is performing better in some areas than others. The report found that levels of carbon monoxide, lead, nitrogen dioxide, coarse particulate matter and sulfur dioxide have all decreased in the past 10 years. However, ozone and fine particle levels have not declined, and ongoing efforts will be required to better understand the impacts of this.
In fact, the report concludes that identifying the sources of fine particles in the air (that is, particulate matter less than 2.5 microns in size [PM2.5]) and reducing their presence in the atmosphere is one of the next major challenges on the air quality front.
“We do not yet fully understand all the processes that lead to fine particle formation. In some cases they can condense out of the gas phase in the atmosphere, for example, which makes it difficult to trace the source,” says Dr Emmerson.
“There needs to be further research into this because these fine particles can be breathed deeper into the lungs than larger particulate matter, which can cause greater health impacts. They can also be transported further and persist for longer in the atmosphere.”
In a positive development since the last State of the Environment report in 2011, Australia has put in place air quality limits for these small particles that are supported by health experts.
The health impacts of air pollution can be serious. According to the report, particulate matter in the air has been linked to decreased lung function, increased respiratory symptoms, increased chronic obstructive pulmonary disease, increased cardiovascular and cardiopulmonary disease, and increased mortality. The Australian Institute of Health and Welfare estimated in 2016 that about 3000 deaths are attributable to urban air pollution in Australia each year.
“Unfortunately, these limits can be exceeded because of events such as bushfires, smog, dust storms and use of domestic wood heaters,” says Dr Emmerson.
The report notes that sources of air pollution can be both natural and as a result of human activity. The sources include things like industrial emissions, vehicle and road traffic emissions, smoke from domestic wood heaters, as well as dust and bushfires.
In fact, the humble domestic wood heater has been singled out as a particularly potent source of pollution in winter in many regions, with smoke from the heaters contributing 50 per cent or more to levels of small particulate matter, with no effective controls yet implemented because of the social and political complexities of doing so.
The relative good fortune Australians experience when it comes to air quality looks set to be further challenged in the future, with population and urban areas predicted to expand, and the consequent increase in power and transport requirements giving rise to greater emissions of pollutants.
“We have some challenges coming to us that we will need to manage in order to maintain that good air quality,” says Dr Emmerson.
“Along with the increased emissions that will arise from population growth, we will also need to manage the impacts of climate change. For example, extreme heatwaves can change the chemical reactivity of the atmosphere, promoting the formation of photochemical smog.”
On top of this, the report indicates that increasing numbers of fire days will increase smoke production; an increase in heatwaves will encourage people to use cooling systems, which will place pressure on power requirements and increase emissions to the atmosphere; and reduced rainfall and drought could promote dust events.
Asked what she will focus on between now and the next State of the Environment report in five years, Dr Emmerson says she will be working to improve air quality prediction models and how they can be used to provide better advice on safe levels of human exposure to pollutants when and where they occur.
Read the highlights from the Atmosphere chapter from the 2016 State of the Environment report.