For the purpose of this Strategy, air is described as the surrounding outside air that is found within the Swan Region. Air quality refers to the condition of the air we breathe compared to measured acceptable guidelines such as the National Environmental Protection Measure (NEPM) Guidelines. Pollution of air occurs when a contaminant or polluting substance does not disperse. Such pollution can have negative consequences for human health and the environment.
Air pollution can arise from human activity and natural processes. Man-made sources include the combustion of fossil fuels and wood, emissions from motor vehicles, oil and gas refineries and industrial processes, and particulate matter associated with mining, land clearing and fire. Natural sources of pollutants include bushfires and wind erosion. Some pollutants can chemically react in the atmosphere to form secondary pollutants. For example, photochemical smog occurs when ozone, nitrogen oxides and volatile organic compounds react with sunlight at high temperatures (Environmental Protection Authority 2007).
Perth’s air quality is measured according to the NEPM (Ambient Air Quality) Standards. Overall, Perth’s air quality meets the minimum standards, with the levels of some pollutants being exceeded at certain times of the year (Environmental Protection Authority 2007). The most recent air quality monitoring report revealed that the levels of carbon monoxide, nitrogen dioxide and sulfur dioxide did not exceed the NEPM standards at any of the monitoring sites (Department of Environment Regulation 2014). The two key pollutants where standards were exceeded were ozone (photochemical smog) and particulates associated with smoke haze (Department of Environment Regulation 2014).