Sulfur dioxide and oxides of nitrogen
Sulfur dioxide and oxides of nitrogen are common pollutants that are generally
present at low levels in the air we breathe. Emissions of sulfur dioxide and
oxides of nitrogen vary across Australia depending on the nature of local
industries and urban populations.
Sulfur dioxide
Oxides of nitrogen
Sulfur dioxide is an invisible gas with a sharp smell that
can affect human health when high levels are breathed
in. While sulfur dioxide in air is produced by sources
including motor vehicles, the main source is industrial
activity including electricity generation, metal refining,
or smelting.
Oxides of nitrogen are a mixture of gases composed of
nitrogen and oxygen. Two of the most toxicologically
significant compounds are nitric oxide and nitrogen
dioxide. At low levels, oxides of nitrogen can irritate the
eyes, nose, throat and lungs, possibly leading to
coughing, shortness of breath, tiredness and nausea.
Oxides of nitrogen may be inhaled or absorbed through
the skin.
At low concentrations across the environment, sulfur
dioxide can reduce crop productivity and at higher levels
can adversely affect both land and water ecosystems.
Sulfur dioxide levels in air are not generally a problem in
Australia. Fuel standards that allow only low sulfur
levels in fuels have significantly reduced sulfur dioxide
in vehicle exhaust and subsequently reduced the levels in
air even further.
However higher levels of sulfur dioxide in air are found
around petrol refineries, chemical manufacturing
industries, mineral ore processing plants and power
stations.
At high levels, sulfur dioxide can cause irritation to the
nose, throat and airways leading to coughing, wheezing
and shortness of breath. People with asthma or similar
conditions are most at risk of experiencing health
effects.
Image credit: John Baker
environment.gov.au
Sources of oxides of nitrogen emissions include:



Industrial – electricity supply, mining, oil and gas
extraction and petroleum manufacturing
Human impact – burn-off activities, wood heating,
cigarette smoke, motor vehicles, lawn mowers,
shipping/boating, aeroplanes and railways
Natural processes – lightning or bushfires/wildfires
Most people are exposed to oxides of nitrogen by
breathing in polluted air. People who live near
combustion sources such as coal burning power plants,
urban areas with high motor vehicle usage, or live in
households that burn a lot of wood may be exposed to
higher levels.
Governments and industry need to work together to
develop solutions to minimise air pollution to protect
the health of the environment and of local communities.
State and territory governments have primary
responsibility for managing air pollution. They regulate
pollutants, including sulfur dioxide and oxides of
nitrogen, from a range of sources including mines and
power stations.
The Australian Government also manages sulfur
dioxide emissions on a national scale through
implementing national fuel quality and vehicle emissions
standards.
National Pollutant Inventory
The National Pollutant Inventory (NPI) is an internet
database that provides publicly available information on
pollutants to the environment. Facilities that meet NPI
reporting thresholds are required to report their annual
emissions of 93 pollutants to their state or territory NPI
team, who assess the reports for accuracy and quality
and submits the facility data to the Australian
Government for publication on the NPI website
(www.npi.gov.au). This allows communities to view
annual data regarding the emission of pollutants that
may affect them locally.
The NPI reports on emissions of sulfur dioxide and
oxides of nitrogen. As reported to the NPI, the highest
emissions to air of sulfur dioxide include basic
non-ferrous metal manufacturing, for example
refineries, electricity generation and fuel combustion.
The highest emissions to air of oxides of nitrogen
include electricity generation, motor vehicles and
burning for fuel reduction or regeneration.
Figure 1 shows the total emissions of sulfur dioxide and
oxides of nitrogen as reported to the NPI over the last
ten reporting periods.
environment.gov.au
1600
1400
1200
Kilotonnes
What are governments doing
to combat sulfur dioxide and
oxides of nitrogen?
1000
800
Sulfur
dioxide
600
400
Oxides
of
nitrogen
200
0
Reporting year
National Clean Air Agreement
The Australian Environment Minister, the
Hon. Greg Hunt MP, has secured the agreement of all
Australian Environment Ministers to establish a
National Clean Air Agreement (Agreement) to ensure
that the community continues to enjoy clean air and
address the impacts on human health and the
environment.
Australian Environment Ministers are working to
develop an Agreement by July 2016. Feedback has been
sought from the community on the Working towards a
National Clean Air Agreement – Discussion Paper. This
included consideration of priorities such as
strengthening ambient air quality reporting standards
for sulfur dioxide and nitrogen dioxide under the
Ambient Air Quality National Environment Protection
Measure, recognising that high levels of sulfur dioxide
and nitrogen dioxide emissions are of environmental
and health concern to local communities.
The Agreement will focus on actions to reduce air
pollution and improve air quality through cooperative
action between industry and government at the national,
state and local level. The Agreement is being designed to
incorporate a range of existing, new and complementary
measures to improve Australia’s air quality.
Further information can be found via:
http://www.environment.gov.au/national-clean-a
ir-agreement.
National Environmental Science
Programme
Environment Ministers are considering options to
further mitigate PM pollution from wood heaters.
The Australian Government is supporting practical and
applied environmental research under the
National Environmental Science Programme, including
$8.8 million in funding for ‘Clean Air and Urban
Landscapes Hub’. This Hub will focus on increasing the
understanding of the environmental and social impacts
of air pollution in urban and peri-urban areas.
Review of Fuel Quality Standards Act
2000
National ambient air quality standards
The review of the Act will commence in June 2015 and
report in late 2015. The review will investigate and
report on best management practices for fuel quality. A
subsequent stage will be to consider current fuel quality
standards, including the petrol and diesel standards, to
ensure that they deliver the best possible air quality
outcomes.
The National Environment Protection (Ambient Air
Quality) Measure (NEPM) establishes national ambient
air quality standards and provides a national framework
for monitoring and reporting on six common air
pollutants, including sulfur dioxide and nitrogen
dioxide.
Environment Ministers are considering changes to
strengthen the Ambient Air Quality NEPM to allow
stronger actions to mitigate sulfur dioxide and nitrogen
dioxide pollution.
The Australian Government has commenced a review
of the Fuel Quality Standards Act 2000 to ensure that
Australian motorists have access to high quality fuel,
which will continue to deliver improved air quality
outcomes.
© Commonwealth of Australia, 2015.
Non-road spark ignition engines and
equipment
Emissions from non-road spark ignition engines and
equipment can be a significant source of sulfur dioxide
and oxides of nitrogen in some urban air-sheds. These
engines cover a wide range of petrol powered
equipment, including marine outboard engines and
gardening equipment such as leaf blowers and chain
saws.
This equipment is a significant source of pollution
because it doesn’t have the same advanced emission
controls found in on-road engines.
Environment Ministers are considering additional work
to further mitigate sulfur dioxide and oxides of nitrogen
pollution from non-road spark ignition engines and
equipment.
Wood heaters
Emissions from wood heaters contain sulfur dioxide
and oxides of nitrogen, as well as other pollutants, which
can be significant contributors to air pollution,
particularly in the cooler months.
The Australian Government has undertaken a number
of programmes with a focus on wood heaters and
environment.gov.au
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and do not necessarily reflect those of the Australian Government
or the Minister for the Environment.
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