Approved Methods (2022)
- Current

Approved Methods (2026)
- Proposed

Reason for change

Meteorological data

At least one year of site-specific or site-representative meteorological data must be used for an air quality assessment. Prognostic met data may be used where measured data is unavailable or of insufficient quality

An assessment must include at least one of the following:

One year of site-specific data (on-site measured)

Three years of site representative data (off-site measured)

Five years of prognostic data (synthetic data)

To encourage the use of site-specific data, which provides more accurate predicted impacts.
Also to ensure that data which is less representative (e.g. prognostic data) covers a larger range of meteorological conditions.

Dispersion Modelling

AUSPLUME is the approved dispersion model. Alternative models (e.g. CALPUFF and TAPM) can be used when appropriate

AERMOD is the approved model and CALPUFF when a Gaussian plume model is not appropriate. Alternative models may be used when appropriate.

AUSPLUME is no longer widely used in NSW and has largely been replaced by AERMOD. AERMOD is not suitable for all situations.

Impact Assessment Criteria

The criteria for individual toxic air pollutants are based on Victoria EPA's superseded criteria from 2001, which were originally adopted from safe work limits.

Averaging period is 1-hour and applied at 99.9^th percentile for refined assessments.

The impact assessment criteria for individual toxic air pollutants have been updated:

Short-term (1-hour) criteria is based on current health data

Addition of annual averaging periods

Individual toxic air pollutants are assessed at 100^th percentile.

The criteria for individual toxic air pollutants are aligned with current international health-based data. Annual criteria have been introduced for pollutants with chronic health impacts, while the 1-hour averaging period continues to apply to all individual toxic air pollutants.

Assessment at the 100^th percentile ensures regulatory consistency with common pollutants.

Reduction of harmful substances

Principal toxic air pollutants must be minimised to the maximum extent achievable through the application of best practice process design and/or emission controls.

Fine particulate matter (PM_2.5) AND principal toxic air pollutants must be minimised to the maximum extent achievable through the application of best practice process design and/or emission controls.

To reduce the risks to human health and prevent degradation of the environment.

The Significant Impact Level (SIL)

N/A

SILs have been introduced for SO₂, NO₂, PM_2.5 and PM₁₀. Generally, no further evaluation of cumulative impacts will be required if incremental impacts are below SILs.

To allow low-risk proposals to move through the assessment process with less regulatory burden and to encourage better environmental controls for proposals. i.e. “to rationalise, simplify and strengthen the regulatory framework for environment protection”
- POEO Act – Section 3

Degradation Prevention Threshold (DPT)

N/A

If a proposal exceeds the DPT, a Mitigation Options Analysis (MOA) must be conducted. The MOA must demonstrate that all mitigation measures are being implemented to minimise impacts of pollution as far as practicable.

To drive the reduction of impacts through greater consideration and uptake of mitigation measures.

Mitigation Options Analysis

N/A

Chapter 9 has been included under the proposed Approved Methods

Guidance on how to demonstrate implementation of all practicable mitigation measures.

Setting licence conditions

Limited information on fugitive dust

Chapter 11 includes guidance on how the NSW EPA regulates fugitive dust

To set minimum requirements regarding the assessment and regulation of fugitive dust – allowing increased regulatory visibility for the setting of licence conditions and to strengthen site specific air quality management plans.

Complex mixtures of odorous air pollutants

No guidance on determining the “population of affected community” to determine the odour impact assessment criteria

A methodology is included to allow the determination of affected population

To improve consistency between assessments.