On 18 May 2021 the National Environment Protection (Ambient Air Quality) Measure (NEPM) was amended to update the ambient air quality pollutant concentration standards for nitrogen dioxide (NO2), sulfur dioxide (SO2) and ozone (O3).
The NEPM amendment accounts for the latest scientific advice about the health impacts of these pollutants and includes the following changes (Refer to Table: NEPM standards in 2021):
- 1-hour and annual NO2 standards as well as the 1-hour and daily SO2 standards strengthened.
- 1-hour and 4-hour average O3 standards and annual average SO2 standard removed.
- 8-hour average O3 standard established. The exceptional events rule that applies to the particle standards will also now apply to O3 given the linkages between elevated O3 levels and fire events. The rule will exclude O3 exceedance days determined as being directly associated with an exceptional event when assessing compliance with the 8-hour standard.
- single day exceedances allowed for all gases, including carbon monoxide, removed.
No changes were made to the standards for PM10 or PM2.5 in this update to the NEPM. For more information on the updates to the NEPM, refer to the National Environment Protection Council (NEPC) website.
NEPM standards in 2021
|Pollutant||Averaging period||Old NEPM||>New NEPM||Change<|
|Photochemical oxidants (as ozone) (O3)||1-hour||10||-||Removed|
|8-hour||-||6.5 a||Established e|
|Nitrogen Dioxide (NO2)||1-hour||12||8||Reduced e|
|Sulfur dioxide (SO2)||1-hour||20||10 b||Reduced e|
|Carbon monoxide (CO)||8-hour||9||9||No change e|
|Particulate matter ≤10μm in diameter (PM10)||1-day||50||50||No change e|
|Particulate matter ≤2.5μm in diameter (PM2.5)||1-day||25||25 c||No change e|
|Annual||8||8 d||No change|
– Not applicable
- The exceptional event rule now allows 8-hour ozone exceedances to be classified as an exceptional event, which are those events directly influenced by smoke from bushfires or hazard reduction burns. This data should still be reported, and the exceptional events described. However, when assessing compliance against the annual goals, these exceedances shall be excluded.
- The 1-hour average SO2 standard will further reduce to 7.5 pphm from 2025.
- The goal for daily average PM2.5 will be 20 µg/m3 from 2025. The goal will provide a framework for continuous improvement and facilitate a review of the PM2.5 standard.
- The goal for annual average PM2.5 will be 7 µg/m3 from 2025. The goal will provide a framework for continuous improvement and facilitate a review of the PM2.5 standard.
- No allowable exceedance day for this standard.
Effect of new standards
The new NEPM standards came into force part-way through the year during 2021. For the NSW annual air quality statement 2021, it has been assumed that the new and more stringent standards would apply for the whole year. But for the purpose of assessing the impacts of the changes, the relevant elevated pollutant levels for 2021 are compared against both new and old standards below.