Sulfur dioxide originates mainly from industrial activities, such as smelting mineral ores, oil refining, and coal-fired power generation.
Motor vehicle fuels in Australia have low sulfur content and are of less concern than industry as sulfur dioxide source.
We monitor sulfur dioxide levels in five regions:
- Southeast Queensland (SEQ)
- South West Queensland (SWQ)
- Gladstone
- Townsville
- Mt Isa.
Sulfur dioxide concentrations in SEQ and Gladstone rarely exceed National Environmental Protection (Ambient Air Quality) measure (NEPM) standard. Since 2014, in these regions:
- the maximum hourly concentrations have exceeded the NEPM standard on only two days in each region
- the maximum 24-hour concentrations have only exceeded the NEPM standard on one day in SEQ.
The last coal-fired power station at Swanbank closed in 2012. Since then, oil refining at the mouth of the Brisbane River is the main contributor to elevated sulfur dioxide concentrations in SEQ. Refining crude oil with a higher sulfur content has contributed to a rise in maximum sulfur dioxide concentrations since 2013.
In Gladstone, several industry facilities converting from coal to natural gas as a fuel source has seen sulfur dioxide levels trend downwards over the past 20 years.
In Mt Isa, smelting operations next to the city have resulted in one-hour and 24-hour sulfur dioxide concentrations exceeding the NEPM standard on up to 85 and 56 days per year, respectively, over the past decade.
The number of exceedances in any given year depends on several factors, including weather conditions, smelter production levels and the extent of sulfur dioxide capture for sulfuric acid production. The annual average sulfur dioxide concentrations in Mt Isa have trended down over this period.
In SWQ and Townsville, with no major emission sources, maximum 24-hour and one-hour concentrations have been less than 25% of the respective NEPM standard over the last decade.
