For NPI reporting, PAHs are an aggregate substance group made up of the 16 US EPA Priority Pollutant PAHs (or the subset of those for which data is available) and reported as total PAHs. This list of PAHs and their Chemical Abstract Services Registry (CASR) numbers is provided below.

• Acenaphthene (83-32-9)
• Anthracene (120-12-7)
• Acenaphthylene (83-32-9)
• Benz(a)anthracene (56-55-3)
• Benzo(a)pyrene (50-32-8)
• Benzo(b)fluoranthene (205-99-2)
• Benzo(ghi)perylene (191-24-2)
• Benzo(k)fluoranthene (207-08-9)
• Chrysene (218-01-9)
• Dibenz(ah)anthracene (53-70-3)
• Fluoranthene (206-44-0)
• Fluorene (86-73-7)
• Indeno(123-cd)pyrene (193-39-5)
• Naphthalene (91-20-3)
• Phenanthrene ((85-01-8)
• Pyrene (129-00-0)

Emissions of total PAHs as equvalents of Benzo(a)pyrene should be reported to the NPI.

For the purpose of NPI reporting, Total VOC are defined as any chemical compound based on carbon chains or rings with a vapour pressure greater than 0.01 kPa at 293.15 K (i.e. 20ºC), that participate in atmospheric photochemical reactions.
Specifically excluded are:

• carbon monoxide
• methane
• acrylamide
• benzene hexachloro
• biphenyl
• chlorophenols
• n-dibutyl phthalate
• ethylene glycol
• di-(2-ethylhexyl) phthalate (DEHP)
• 4,4-methylene bis 2,4 aniline (MOCA)
• methylenebis
• phenol, and
• toluene-2,4-diisocyanate.

The intent of the inclusion of Total VOCs is in recognition of the combined effect of compounds that contribute to smog formation that may not otherwise have been captured due to individual substances not meeting a usage threshold in their own right. The most common sources of Total VOCs emissions are from the storage and use of liquid and gaseous fuels, the storage and use of solvents and the combustion of fuels.

Download the definition

• NPI definition for Volatile Organic Compounds

If you cannot access the definition, please contact the department — npi@environment.gov.au — to organise a suitable alternative format.

The NEPM for the NPI  states that total nitrogen refers only to those amounts of nitrogen that give rise to nitrate/nitrite ions. Since this may be possible for a range of nitrogen compounds in a range of environmental conditions, the following pragmatic definition can be applied:

Total Nitrogen is the sum of nitrate (NO₃), nitrite (NO₂), organic nitrogen and ammonia (all expressed as N).

Note: for laboratory analysis purposes Total Kjeldahl Nitrogen (TKN) is a test performed that determines both organic nitrogen and ammonia.

For the NPI, polychorinated dioxins and furans should be reported based on the toxic equivalence (TEQ), which is a means of scaling the emissions of each species of dioxin and furans according to their relative toxicity.