State of the Environment Report 2007
'Atmosphere' refers to all air above the ground up to and including the stratosphere. It includes indoor air within houses and vehicles but not workplaces. The atmosphere surrounding the Earth consists of 79% nitrogen, 20% oxygen and a range of other gases and particles make up the balance (1%). It consists of several layers including the troposphere (in which we live), the stratosphere (in which the ozone layer is contained), and outer layers including the mesosphere, thermosphere and exosphere. The atmosphere plays a critical role in regulating global, regional and local climate and is essential to supporting life on Earth. Oxygen is required for life, ozone protects us from harmful solar radiation and historically greenhouse gases have helped maintain a temperature range suitable for life. However, the composition of the atmosphere is changing with increasing human pressures.
Atmospheric pollutants can have an adverse effect on human heath and the environment, and are derived from both human activity and natural processes. Significant sources from human activity include combustion of fossil fuels and wood, motor vehicles, release of hydrocarbons from oil and gas refining, emissions from industrial processes or intensive agriculture, and particulate matter associated with mining, land clearing and bushfires. Natural sources of pollutants include volcanic eruptions, wind erosion and bushfires. Some pollutants can chemically react in the atmosphere to form secondary pollutants, for example photochemical smog.
Air pollutants continue to be of community concern (Australian Bureau of Statistics, 2004) and there are several mechanisms in place to protect human and environmental health. These include a series of national environment protection measures (NEPMs) related to ambient air quality, air toxics, data collection for the National Pollutant Inventory and diesel vehicle emissions. It is a requirement that all measures be implemented by Australian states and territories, who must report on compliance. Standards for ambient air quality may be set over various timeframes to determine persistence and associated health impacts. They may also specify a number of allowable exceedences of a standard per year. As requirements to monitor for compliance with NEPM standards only apply in areas of more than 25 000 people, many areas in Western Australia are not monitored, but the standards are still considered relevant for all human settlements in WA.
The impacts of changes in the atmosphere can be observed on different scales. The 'greenhouse effect' (now generally known by the more accurate term climate change) and depletion of the stratospheric ozone layer are significant global atmospheric issues. On the regional and local scale, photochemical smog, particulates (including particulate haze and dust) and sulfur dioxide are well-recognised air quality problems.
There have been 39 exceedences of the ambient air quality NEPM standards for all pollutants between 1998 and 2005 (Table A0.1). This figure does not include the smallest type of particulate matter (PM2.5) because at present it is an advisory standard only. Although serious, the number of exceedences does not appear to have increased over time. The increase in background concentration of ozone is potentially serious, with a greater number of days expected to approach or exceed the standard in the future.
![Table A0.1: Exceedences of National Environment Protection (Ambient Air Quality) Measure standards, 1998–2005. [Data source: Department of Environment and Conservation [ver. 2007]. Notes: (a) Department of Environment monitoring sites only. (b) Advisory standard, not yet a defined standard.]](/site/files/images/Table-A0.1_Large.jpg)
In 2007, air pollutants were being measured at 5 settlements in WA (Perth, Bunbury, Albany, Geraldton and Busselton) for public health reasons. Within Perth, air pollutants are measured at 10 sites throughout the metropolitan area (Figure A0.1). The extent of air pollutant monitoring varies over time; usually in response to community health concerns, research studies and investigations, or regulatory requirements such as NEPM requirements or environmental conditions. In addition, shorter term studies are sometimes conducted as necessary but the monitoring is not on-going. Sites are usually selected based on risk of pollutants being present, low exposure or background sites and population requirements under the NEPM.
Monitoring stations are also located in Busselton and Bunbury for particulates, including PM10 (10 microns (mm) or less in size) and PM2.5 (2.5 microns or less). Particle monitoring equipment has recently been installed at Albany and Geraldton but no monitoring data is available yet. A monitoring station operated in Dampier between 1998 and 2000, measuring carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), and PM10, but has now been decommissioned. In the past Bunbury's station measured carbon monoxide.
![Figure A0.1: Metropolitan air quality monitoring sites and the pollutants measured. [Data source: Department of Environment and Conservation – Air quality monitoring sites [ver. 2007], Department of Planning and Infrastructure – Urban extent [ver. 2004]; Presentation: EPA.]](/site/files/images/Figure-A0.1_Large.jpg)
An inventory of emissions to Perth's airshed was first completed in 1992-93 and followed up in 1998-99, allowing for an analysis of change over the two periods (Department of Environmental Protection, 2002b) (Table A0.2). The emissions were divided into four source categories - motor vehicles on the road, industrial and commercial, biogenic and natural and other area-based (diffuse) sources that are not included elsewhere (eg. wood heaters, gas used in homes, solvents, cigarettes, railways, marine craft, service stations, off-road vehicles, lawnmowing, aircraft, leakage of gas from supply network, swimming pools, dry cleaning and cutback bitumen).
![Table A0.2: Change in annual estimated emissions in the Perth airshed between 1992–93 and 1998–99. [Data source: Department of Environmental Protection (2002b). Analysis: EPA. Note: (a) This does not include particulate estimates for brickworks in 1992-93.]](/site/files/images/Table-A0.2_Large.jpg)
Emissions estimates for oxides of nitrogen, particulates and sulfur dioxide all increased between 1992-93 and 1998-99 - overall 28%, 58% and 3.6% respectively (Department of Environmental Protection, 2002b). Emissions for carbon monoxide, total reactive organic compounds and lead were estimated to have decreased by 1%, 14% and 88% respectively. Some of these changes can be attributed to sampling - more industrial facilities were included and additional area-based source categories were added to the 1998-99 inventory. Increases in some motor vehicle emissions appear to be related to an increase in vehicle numbers and activity levels. Decreases in emissions often appear to be related to regulations, for example emissions estimates for reactive organic compounds and carbon monoxide from motor vehicles appear to have decreased as more cars on the road comply with design regulations for emissions from new vehicles (Department of Environmental Protection, 2002b).
Changes in emissions from some sources may also be attributed to the use of updated emission factors (numbers used for technical calculations) for the 1998/99 inventory (Department of Environmental Protection, 2002b). Therefore it is difficult to directly compare the 1992-93 and 1998-99 emissions for these sources. Also, variation in emissions may be attributed to improvements in methodology and data quality, rather than an actual change in emissions. For example, particulate emissions from brickworks were not included in 1992-93 data but were included in the calculations for 1998-99 (Department of Environmental Protection, 2002b).
Work on a third inventory of emissions into Perth's airshed is underway; however details are not yet available.
Some industries are required to measure atmospheric pollutants as part of development or operational requirements to protect the environment and the health of local communities (Table A0.3).
Twenty actions were identified for the 'Atmosphere' theme in response to the 1998 State of the Environment Report (Government of Western Australia, 1998). Of these, 40% remain incomplete, 25% have been completed but not evaluated and 35% have been completed and evaluated. Compared to many other environmental issues affecting the State, air quality is monitored and reported in select locations. The nature of emissions and ambient air pollutants means that changes in condition and pressure are easy to detect, and that rigorous reporting procedures and management practices are in place.
2.1 Implement the Perth Air Quality Management Plan. Although the plan was released in 2000 and much progress made, many parts have yet to be implemented.
2.2 Develop and implement air quality management plans for regional areas. Management plans should be developed for problem regional areas using the Perth Air Quality Management Plan as a model.
