Air toxics and indoor air quality in Australia

State of knowledge report
Environment Australia, 2001
ISBN 0 6425 4739 4

Part A: Air toxics (continued)

Priority air toxics

5.1 Introduction

The following summary information has been extracted from the Report of the Technical Advisory Group on Prioritisation of Air Toxics for Living Cities Air Toxics Program, which is available on the internet.1

On 1 February 2000, the Technical Advisory Group (TAG)2 met in Melbourne to develop an agreed list of priority pollutants for consideration under the Air Toxics Program. The list of priority pollutants was further refined at subsequent meetings of the TAG on 23 March 2000 (community representatives from the Steering Groupo (SG) were invited to attend); the SG on 19 May 2000; and meetings of the TAG and SG on 15 September 2000.

The list of priority pollutants has been endorsed by the Commonwealth Minister for the Environment and Heritage, the Hon Senator Robert Hill. The list will be used to focus future activities under the Living Cities – Air Toxics Program and was also identified by the Commonwealth as a starting point for identifying priority pollutants for inclusion in a new NEPM to address air toxics.

5.2 Selection of priority pollutants

The process for identifying priority pollutants was originally considered at a joint meeting of the SG and TAG on 16 December 1999. At this meeting, Professor Ian Rae3, the TAG chair, noted that there was a substantial body of work on prioritising air pollutants, so a major new investment of time and effort to develop a new methodology was unwarranted. It was, therefore, recommended that the TAG should make use of existing national and international prioritisation schemes, recognising and compensating for their shortcomings, so as to derive within a reasonable time a shortlist of substances of greatest concern. Professor Rae's approach was subsequently accepted by the joint meeting.

In the lead up to the TAG's first meeting, Professor Rae circulated a background paper to members, outlining his approach for prioritising air pollutants. Professor Rae's paper offered critiques of the three existing prioritisation methodologies – those used by EPA Victoria, the US EPA and the NPI – and outlined how the outputs from these methodologies could be used in developing a priority list for the Air Toxics Program.

The TAG accepted Professor Rae's background paper and chose to begin its process with the 90 substances that had been ranked highest by the NPI (from an initial starting list of 400 substances), taking into consideration specific Australian conditions. Recognising that some air pollutants of potential concern might have been omitted from the NPI list, it was agreed that there would be an opportunity to consider additional substances separately.

The TAG's activities were intended not to rank individual substances, but rather to produce an initial list of priority substances for further consideration under the Air Toxics Program. The Air Toxics Program priority listing process resembled that used by the US EPA – that is, a 'meta-analysis' based on a number of existing priority lists.

In developing the priority list, a number of issues were explicitly recognised. First, the list was to be considered a 'living' list, allowing for the opportunity to add and remove substances from the priority listing as appropriate information came to hand. Second, the outright exclusion of a substance or its consideration in the indoor context only in no way was to detract from its significance in terms of other government programs. Third, it was also agreed that the US EPA list of priority pollutants could not be adopted, because of significant differences in the scale and type of industry between Australia and the United States.

In keeping with the definition for 'air toxics' (Section 1.2.3), agreed and adopted under the ATP, the criteria pollutants (ie the six pollutants covered by the existing Ambient Air Quality NEPM) were excluded by the TAG. In addition, substances which were excluded from NPI reporting because they were either subject to regulation under other protocols or the subject of national management plans (eg polychlorobiphenyls, hexachlorobenzene, organochlorine pesticides) were also excluded by the TAG.

Although there was some discussion of certain agricultural and veterinary chemicals, it was acknowledged that existing schemes, such as those under the NRA, were better placed to deal with these pollutants (see Section 1.3.2).

5.3 Priority air toxic pollutants: recommended list

As a result of the process described above, TAG identified 28 pollutants for consideration as priority pollutants under the ATP. They are listed in alphabetical order in Table 5.1.

Table 5.1: Table 5.1 List of priority pollutants identified under the Living Cities – Air Toxics Program
Acetaldehyde Methylenebis (phenylisocyanate)
Acroleinb Nickel and compounds
Acrylonitrile Oxides of nitrogen (indoor air)a
Arsenic and compounds Polycyclic aromatic hydrocarbons (PAHs)
Benzene Respirable particulate matter (indoor air)a
1,3-Butadiene Polychlorinated biphenyls (PCBs)b
Cadmium and compounds Phthalatesb
Carbon monoxide (indoor air)a Polychlorinated dioxins and furans
Chromium (VI) compounds Styrene
Dichloromethane Tetrachloroethylene
Fluoride compounds Toluene
Formaldehyde Toluene-2,4-diisocyanate
Lead and compounds (indoor air)a Total volatile organic compounds
Mercury and compounds Trichloroethylene
Methyl ethyl ketone Vinyl chloride (monomer)
Methyl isobutyl ketone Xylenes

a Criteria pollutants to be considered in the indoor context only. The definition for 'air toxics' agreed and adopted under the ATP excludes consideration of the criteria pollutants (ie the six pollutants covered by the existing Ambient Air Quality NEPM). It was agreed that the significant impact these criteria pollutants have on indoor air quality should be acknowledged. Whilst the ATP includes consideration of indoor air quality, the current NEPC Act would not allow consideration of indoor air quality in the making of an air toxics NEPM.

b Pollutants not in the NPI. The category 'phthalates' combines two individual entries from the NPI, namely, dibutyl phthalate and di-(2-ethylhexyl) phthalate. The NPI presumably excluded PCBs as they were being addressed separately by the PCB Management Plan which was being developed at the same time the NPI list was being finalised.

Whilst the NEPC Act 1994 does not allow consideration of indoor air quality in the making of NEPMs, it was agreed that the significant impact the air toxics and criteria pollutants have on indoor air quality should be acknowledged. To this end, four of the six criteria pollutants were identified as pollutants of concern to indoor air: carbon monoxide, lead, oxides of nitrogen, and particles (both PM10 and PM2.5). Sulfur dioxide and ozone were not included because the TAG decided that they were not relevant in the context of indoor air.

5.4 Comparison of priority rankings

Table 5.2 compares the EPA Victoria list of priority hazardous air pollutants and the 1999 US EPA Integrated Urban Air Toxics Strategy4 list of 33 priority air toxics with the full NPI reporting list of 90 pollutants.

Although these lists were derived independently (using some data in common), the overall correlation between them is high. For example, only two of the top 15 substances on the EPA Victoria priority list are not among the US EPA priority list (greater than 85% match). All but one of the substances on the EPA Victoria list are on the NPI list of 90 substances. Additionally, 70% of substances on the US EPA priority list are on the full list that will have to be reported under the NPI.

Table 5.2: Comparison of different priority lists with the full NPI reporting list a,b
CASR No. NPI 90 substancesa,b NPI 36 substancesc US EPA 33 urban air toxics EPA Victoria 24 priority HAPs ATP 32 priority pollutants
75-07-0 Acetaldehyde   Tick   Tick
64-19-7 Acetic acid {ethanoic acid}        
67-64-1 Acetone        
75-05-8 Acetonitrile        
107-02-8     Acrolein   Tick
79-06-1 Acrylamide        
79-10-7 Acrylic acid        
107-13-1 Acrylonitrile {2-propenenitrile}   Tick Tick Tick
NA Ammonia (total)        
62-53-3 Aniline {benzenamine}        
744036-0 Antimony and compounds        
7440-38-2 Arsenic and compounds Tick Tick Tick Tick
71-43-2 Benzene Tick Tick Tick Tick
608-73-1 Benzene hexachloro- {HCB}   Hexachloro-benzene    
7440-41-7 Beryllium and compounds   Tick    
92-52-4 Biphenyl {1,1-biphenyl}        
7440-42-8 Boron and compounds        
106-99-0 1,3-Butadiene {vinyl ethylene} Tick Tick Tick Tick
7440-43-9 Cadmium and compounds Tick Tick Tick Tick
75-15-0 Carbon disulfide        
630-08-0 Carbon monoxide Tick     Tick (indoor air)d
56-23-5     Carbon tetrachloride    
7782-50-5 Chlorine        
10049-04-4 Chlorine dioxide        
75-00-3 Chloroethane {ethyl chloride}        
67-66-3 Chloroform {trichloromethane}   Tick    
NA Chlorophenols (di, tri, tetra)        
7440-47-3 Chromium (III) compounds   Tick US EPA does not distinguish between chromium (III) and (VI) compounds Tick EPA Vic. does not distinguish between chromium (III) and (VI) compounds  
7440-47-3 Chromium (VI) compounds Tick Tick
7440-48-4 Cobalt and compounds Tick      
NA     Coke oven emissions    
7440-50-8 Copper and compounds        
98-82-8 Cumene {1-methylethylbenzene}        
NA Cyanide (inorganic) compounds Tick      
110-82-7 Cyclohexane        
117-81-7 Di-(2-ethylhexyl) phthalate {DEHP}       Tick (phthalates)e
106-93-4 1,2-Dibromoethane {ethylene dibromide} Tick Tick    
84-74-2 Dibutyl phthalate       Tick (phthalates)e
        1,4-Dichloro benzene (paradichloro benzene)  
107-06-2 1,2-Dichloroethane   Ethylene dichloride    
75-09-2 Dichloromethane Tick Methylene chloride Tick Tick
      1,3-Dichloro- propene    
64-17-5 Ethanol        
110-80-5 2-Ethoxyethanol Tick      
111-15-9 2-Ethoxyethanol acetate Tick      
141-78-6 Ethyl acetate        
106-35-4 Ethyl butyl ketone        
100-41-4 Ethylbenzene        
107-21-1 Ethylene glycol {1,2-ethanediol} Tick      
72-21-8 Ethylene oxide   Tick    
NA Fluoride compounds Tick   Tick Tick
50-00-0 Formaldehyde {methyl aldehyde}   Tick Tick Tick
111-30-8 Glutaraldehyde Tick      
110-54-3 n-Hexane        
302-01-2     Hydrazine    
7647-01-0 Hydrochloric acid        
7783-06-4 Hydrogen sulfide        
7439-92-1 Lead and compounds Tick Tick   Tick (indoor air) d
1309-48-4 Magnesium oxide fume        
7439-96-5 Manganese and compounds   Tick Tick  
7439-97-6 Mercury and compounds f Tick Tick Mercury Tick
67-56-1 Methanol Tick      
109-86-4 2-Methoxyethanol        
110-49-6 2-Methoxyethanol acetate        
78-93-3 Methyl ethyl ketone Tick   Tick Tick
108-10-1 Methyl isobutyl ketone Tick   Tick Tick
80-62-6 Methyl methacrylate Tick      
101-14-4 4,4'-Methylenebis[2-chloroaniline] {MOCA}        
101-68-8 Methylenebis(phenylisocyanate)       Tick
7440-02-0 Nickel and compounds   Tick Tick Tick
13463-39-3 Nickel carbonyl Tick      
12035-72-2 Nickel subsulfide Tick      
7697-37-2 Nitric acid        
NA Organotin compounds        
NA Oxides of nitrogen Tick     Tick (indoor air) d
NA Particulate matter ≤ 10µ m {PM10} Tick     Tick respirable particles - PM10 and PM2.5 (indoor air) d
108-95-2 Phenol        
7664-38-2 Phosphoric acid        
NA     Polychlorinated biphenyls (PCBs)   Tick
NA Polychlorinated dioxins and furans   Dioxin Dioxins and furans Tick
NA Polycyclic aromatic hydrocarbons {PAHs} Tick Polycyclic organic matter (POM) Tick PAHs Tick PAHs
      Propylene dichloride    
91-22-5     Quinoline    
7782-49-2 Selenium and compounds        
100-42-5 Styrene {ethenylbenzene}     Tick Tick
7446-09-5 Sulfur dioxide Tick      
7664-93-9 Sulfuric acid Tick      
630-20-6 1,1,1,2-Tetrachloroethaneg   1, 1, 2, 2-Tetrachloro ethane    
127-18-4 Tetrachloroethylene Tick Perchloroethylene Tick Tick
108-88-3 Toluene {methylbenzene} Tick   Tick Tick
584-84-9 Toluene-2,4-diisocyanate Tick   Tick Tick
NA Total nitrogen Tick      
NA Total phosphorus Tick      
NA Total volatile organic compounds       Tick
79-00-5 1,1,2-trichloroethane        
79-01-6 Trichoroethylene Tick Tick Tick Tick
75-01-4 Vinyl chloride monomer   Tick Tick Tick
1330-20-7 Xylenes (individual or mixed isomers) Tick   Tick Tick
7440-66-6 Zinc and compounds        

a{} denotes synonyms.
b Indicates the full list of 90 substances under Table 1 of the NPI
.Indicates the 36 substances listed in NPI Table 2.
This is a criteria pollutant. It was agreed that, while criteria pollutants were not 'air toxics' under the definition used by the ATP, they did need to be considered under the ATP's coverage of indoor air quality due to their significance.
e Phthalates combine dibutyl phthalate and di-(2-ethylhexyl) phthalate from the NPI list.
NPI refers to '[heavy metal] and compounds'; US EPA refers to ' [heavy metal] compounds'; EPA Victoria refers to either ' [heavy metal] and compounds' or 'mercury'.
The NPI list of 90 substances currently includes 1,1,1,2-tetrachloroethane CASR No. 630-20-6. The review of the NPI will consider changing this to 1,1,2,2-tetrachloroethane CASR No. 79-34-5.
NA = not applicable
Tick = noted on the relevant list;
empty cells indicate not on the relevant list



2 See Appendix C for terms of reference and membership details for the TAG and SG.

3 Professor Ian Rae was selected to chair the TAG on the basis of his technical competence in the field and previous experience as Chair of the NPI Technical Advisory Panel.

4 US EPA Integrated Urban Air Toxics Strategy, available at 


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