Atmosphere: Air toxics
- Author
- Reviewer
- Key findings
- Indicators and summary of status
- Importance
- Pressure and condition
- Response
- References
Author
Phil Kingston, Environmental Protection Agency
Reviewer
Scott McDowall, Environmental Protection Agency
Key findings
- Current measurements of concentrations of air toxics indicate that levels are well below draft national standards, but monitoring continues in order to provide further information needed to understand the impact of these levels on health and the environment.
Indicators and summary of status
Indicator |
Status of indicator |
Measured concentrations of toxic air pollutants |
Well below air toxics NEPM goal values |
Importance
Air toxics, also referred to as 'hazardous air pollutants' (HAPs), are contaminants present in ambient air in trace amounts that have characteristics such as toxicity and persistence that may make them a hazard to human health, plant growth and animal life ( NEPC 2003).
Prolonged exposure to air toxics, even at low concentrations, can have serious health and environmental effects, but information on safe ambient levels is limited; as a result, these contaminants have become an emerging air quality issue and the subject of increased concern.
The National Environment Protection (Air Toxics) Measure (Air Toxics NEPM) provides a framework for monitoring, assessing and reporting on ambient levels of five air toxics-benzene, formaldehyde, toluene, xylene and polycyclic aromatic hydrocarbons (PAHs)-to assist in the future development of national air quality standards for these pollutants and has established ambient monitoring methodologies and monitoring investigation levels for these toxic chemicals.
The Air Toxics NEPM uses the term 'monitoring investigation levels' for air toxics: these are not compliance standards but are levels that have been established for assessing the significance of those levels with respect to protection of human health. If these levels are exceeded then further investigation may be appropriate, but exceedence does not indicate that adverse health effects will occur.
Table 3.8 shows the Air Toxics NEPM monitoring investigation levels.
Table 3.8 National Environment Protection (Air Toxics) Measure standards
Pollutant
|
Averaging period
|
Monitoring investigation level
|
Goal
|
Benzene |
Annual average |
0.003 ppm |
Goal is to gather sufficient data nationally by 2008 to facilitate development of a standard. |
Toluene |
24 hours |
1 ppm |
Goal is to gather sufficient data nationally by 2008 to facilitate development of a standard. |
Annual average |
0.1 ppm |
||
Formaldehyde |
24 hours |
0.04 ppm |
Goal is to gather sufficient data nationally by 2008 to facilitate development of a standard. |
Xylenes |
24 hours |
0.25 ppm |
Goal is to gather sufficient data nationally by 2008 to facilitate development of a standard. |
Annual average |
0.2 ppm |
||
Benzo(a)pyrene as a marker for polycyclic aromatic hydrocarbons |
Annual average |
0.3 µg/m³ |
Goal is to gather sufficient data nationally by 2008 to facilitate development of a standard. |
Source: NEPC 2004
Pressure and condition
Sources of air toxics include paints, solvents, lawn mowers, motor vehicles, coal-fired power stations, pesticides, wood heaters, incinerators, bushfires, cigarette smoking, furnishings and building products. Community concern about air toxics has led to the need for more information about the location, sources and quantities of air toxics released and the potential impacts on health, supported by long-term data. Much of the information on emissions has been obtained from the National Pollutant Inventory. The main source of benzene and toluene in urban areas is motor vehicles; other significant contributions come from commercial industrial and domestic sources.
Determination of ambient levels of air toxics is hampered by the relatively few and expensive methods for monitoring air toxics, the detection levels of instrumentation, and the uneven distribution of emission sources in the airshed. The EPA measures the ambient concentrations of four of the air toxics (benzene, toluene, xylene and formaldehyde) in south-east Queensland and Gladstone using a technique known as Differential Optical Absorption Spectroscopy (DOAS). The Springwood station in south-east Queensland is located near a major highway (the South East Freeway) and the Gladstone station (Targinie) is used to assess the impacts of nearby industry.
Benzene
The annual trend graph for benzene (Figure 3.20) shows levels well below the monitoring investigation level of 3 ppb.
Figure 3.20 Trends in annual mean atmospheric benzene concentrations, 2000-06
Source: EPA 2001, 2004a, 2004b, 2004c, 2005, 2006, unpublished
Toluene
Toluene levels for both the 24-hour maximum and the annual mean are far below the monitoring investigation levels of 1000 ppb and 100 ppb respectively (Figure 3.21 and Figure 3.22).
The highest 24-hour maximum toluene concentration of 48 ppb in 2001 has been attributed to burning of predominantly eucalypt bushland adjacent to the Targinie monitoring site.
Figure 3.21 Trends in 24-hour maximum atmospheric toluene concentrations, 2000-06
Source: EPA 2001, 2004a, 2004b, 2004c, 2005, 2006, unpublished
Figure 3.22 Trends in annual mean atmospheric toluene concentrations, 2000-06
Source: EPA 2001, 2004a, 2004b, 2004c, 2005, 2006, unpublished
Xylene
Monitoring for xylene began in 2000 at two sites in south-east Queensland (the Brisbane CBD site was closed in 2004). Monitoring at both sites measures only the p-xylene isomeric component, which normally makes up some 20% of total xylenes. Even factoring in this fraction, xylene levels are well below both monitoring investigation levels of 250 ppb (24-hour maximum) and 200 ppb (annual average) (Figure 3.23 and Figure 3.24) .
Figure 3.23 Trends in 24-hour maximum atmospheric p -xylene concentrations, 2000-06
Source: EPA 2001, 2004a, 2004b, 2004c, 2005, 2006, unpublished
Figure 3.24 Trends in annual mean atmospheric p -xylene concentrations, 2000-06
Source: EPA 2001, 2004a, 2004b, 2004c, 2005, 2006, unpublished
Formaldehyde
Formaldehyde monitoring was carried out at the Brisbane CBD site between 2000 and 2004 (Figure 3.25); measured levels showed a decreasing trend well below the 24-hour monitoring investigation level of 40 ppb.
Figure 3.25 Trend in 24-hour maximum atmospheric formaldehyde concentrations, 2000-04
Source: EPA 2001, 2004a, 2004b, 2004c, 2005
Polycyclic aromatic hydrocarbons
Analysis undertaken as part of the study Fine Particle Composition in Four Major Australian Cities found that average levels of benzo(a)pyrene (used as a marker for polycyclic aromatic hydrocarbons) at Springwood and Rocklea were 0.13 µg/m³ and 0.12 µg/m³, well below the Air Toxics NEPM monitoring investigation level of 0.3 µg/m³ (annual average) ( Hawas et al. 2003).
Response
The focus on air toxics is fairly recent, coming after the development of standards, guidelines, strategies and monitoring programs for the six criteria pollutants (see 'Other pollutants', page 87).
As motor vehicles are one of the main sources of emissions of air toxics, measures that reduce emissions of hydrocarbons from this source will also reduce emissions of air toxics. See 'Reducing motor vehicle emissions', page 77.
Industrial emissions may also be controlled by the setting of licence conditions for environmentally relevant activities under the Environmental Protection Act 1994 (QG 1994).
The Queensland Government is working closely with the Commonwealth and other states to improve fuel quality and introduce stricter Australian Design Rules (ADRs) for emissions from new vehicles. The new ADRs are being progressively introduced to significantly reduce emission limits for hydrocarbons, carbon monoxide, NOx and particulate matter (PM). Information from trials of remote sensing vehicle emissions technology undertaken by the Queensland Government in 2006 will assist in evaluating the extent to which the ADRs and other policies help reduce vehicle emissions.
To further support the reduction of motor vehicle emissions and encourage people to use environmentally friendly methods of travel such as public transport, walking, cycling and car pooling, the Queensland Government established the Smart Travel Centre-Queensland in 2006 to deliver a voluntary behaviour change program, TravelSmart. TravelSmart in Queensland includes community, school and workplace programs designed to reduce private vehicle kilometres travelled (VKT). Local governments are contributing to a reduction in VKT by encouraging transit oriented development, self contained communities, pedestrian and bicycle networks and urban design.
References
EPA 2001, Ambient Air Quality Monitoring in Queensland: 2000 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
EPA 2004a, Ambient Air Quality Monitoring in Queensland: 2001 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
EPA 2004b, Ambient Air Quality Monitoring in Queensland: 2002 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
EPA 2004c, Ambient Air Quality Monitoring in Queensland: 2003 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
EPA 2005, Ambient Air Quality Monitoring in Queensland: 2004 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
EPA 2006, Ambient Air Quality Monitoring in Queensland: 2005 Annual Summary and Trend Report, Environmental Protection Agency, Brisbane.
Hawas, O., Stelcer, E. and Cohen, D. 2003, 'Fine particle composition in four major Australian cities', 3rd Progress Report to Environment Australia, Reference 50282, June 2004.
NEPC 2003, Impact Statement for Air Toxics, National Environment Protection Council, Adelaide.
NEPC 2004, National Environment Protection (Air Toxics) Measure, National Environment Protection Council, Adelaide.
QG 1994, Environmental Protection Act 1994, Queensland Government, Brisbane.
Last reviewed 12 May 2011
Last updated 9 February 2009