The Air Toxics National Environment Protection Measure

Last updated: 01 July 2004

Introduction

The National Environment Protection Measure (NEPM) was developed by a working group of representatives from environment and health agencies around Australia. Federal and State Environment Ministers adopted it in 2004. This means that the NEPM is applicable in all states and territories, including NSW.

Air toxics can mean any air pollutant, but commonly and in this NEPM, the six criteria air pollutants covered by the Ambient Air Quality NEPM (fine particles, lead, sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide) are excluded. Air toxics are typically present in low concentrations (parts per billion) but are of concern, as some may have health effects even at these low levels.

At present the Air Toxics NEPM includes five compounds: benzene, toluene, xylenes, formaldehyde and benzo(a)pyrene (as a marker for polycyclic aromatic hydrocarbons - BaP). A scoping process will soon commence to select more compounds to include in the NEPM.

Purpose

There are no existing (other than occupational) Australian standards for air toxics. All NHMRC air pollution guidelines have been rescinded.

The purpose of the Air Toxics NEPM is to gather information across Australia to improve the understanding of population exposures to ambient air toxics, with a goal of developing standards for these compounds in eight years (2012). Until now, and apart from in NSW (see the Ambient Air Quality Research Project in Related links), there has been very little environmental monitoring of air toxics in Australia. The Air Toxics NEPM requires monitoring at locations where there is a risk of people being exposed to significantly elevated levels of ambient air toxics.

The identification of monitoring sites consists of two steps:

• Stage 1 - environment agencies conduct desktop audits to identify sites that may have high levels of each of the five air toxics
• Stage 2 - environment agencies undertake monitoring according to NEPM requirements at sites identified in Stage 1 where there is a potential for significant population exposure to one or more air toxics

Monitoring for air toxics is to be undertaken at prioritised stage 2 sites.

The NEPM requires the comparison of stage 2 monitoring results with Monitoring Investigation Levels. If Monitoring Investigation Levels are exceeded then further investigation of the cause of the exceedence is appropriate. Further steps to allow comparison with health-based guideline values are also undertaken.

The Air Toxics NEPM requires annual reporting on the implementation of the Measure, covering the identification of monitoring sites, monitoring results, and assessment of actions taken to manage air toxics, including circumstances that led to Monitoring Investigation Levels being exceeded.

Monitoring Investigation Levels

The NEPM refers to both Monitoring Investigation Levels (MIL) and health-based guideline values to assist jurisdictions in the interpretation of monitoring data.

Due to the constraints of the monitoring protocol with regard to averaging period, MIL were derived for some of the compounds from health-based guideline values. For the compounds where the critical effect is not cancer (formaldehyde, toluene and xylenes), the health-based guideline value is based on toxicological and epidemiological evidence as a level below which no health effects are expected. Both types of values are conservative, and exposure to levels below these over the relevant averaging period can be considered unlikely to result in adverse health effects as shown in the table below. Levels above the MIL may need further investigation. Exposures above the health-based guideline values may require risk assessment in order to understand potential population health risks.

The results of this study are available in Technical Report No. 6: BTEX Personal Exposure Monitoring in Four Australian Cities, Department of Environment and Heritage website. For further information, telephone 02 6274 1221.

Related links

• The health reviews on which the NEPM was based can be found at  http://www.ephc.gov.au/nepms/air/air_toxics.html
• Technical Report No. 6, Department of Environment and Heritage  http://www.deh.gov.au/atmosphere/airtoxics/report6/index.html
• Ambient Air Quality Research Project (1996-2001) NSW Environment Protection Authority  http://www.epa.nsw.gov.au/air/dopahhm/index.htm