Sulphur dioxide concentrations
Sulphur dioxide levels in all regions, except for Mount Isa, have met the National Environmental Protection (Ambient Air Quality) Measure (NEPM) annual, 24-hour and 1-hour average standards of 0.020ppm, 0.080ppm and 0.200ppm respectively. Occasional 1-hour and 24-hour NEPM standard exceedances in Mount Isa are due to smelting operations.
Sulphur dioxide originates mainly from industries such as smelting of mineral ores, oil refining and coal-fired power generation.
Higher concentrations of sulphur dioxide are observed in the Gladstone and Mount Isa regions due to industrial emissions.
Motor vehicle fuels in Australia have low sulphur content and are of less concern than industry as a source of sulphur dioxide. The last South East Queensland (SEQ) coal-fired power at Swanbank closed in 2012.
Since 2008, maximum 24-hour concentrations in SEQ, Gladstone and Townsville have been less than 35% of the National Environmental Protection (Ambient Air Quality) Measure (NEPM) 24-hour average standard of 0.080ppm.
- Maximum hourly concentrations in SEQ and Gladstone have exceeded 0.100ppm (half the 1-hour standard) on only 3 days and 1 day respectively since 2009.
- Townsville hourly levels have consistently been less than 0.010ppm, or 10% of the 1-hour average standard.
Although smelting operations adjacent to the city in Mount Isa have resulted in 1-hour and 24-hour sulphur dioxide concentrations exceeding the NEPM standard on up to 45 and 2 days respectively per year over the past decade, annual concentrations have been consistently below 30% of the annual average standard of 0.020ppm. The number of exceedances in any given year depends on a number of factors including weather conditions, smelter production levels and the extent of sulphur dioxide capture for sulphuric acid production.
Relevant Sustainable Development Goals’ targets
Trends in number of exceedances of National Environmental Protection Measures (NEPM) Air Quality Standards for sulphur dioxide concentrations, and annual average concentrations, by airshed for 2000–2019.