Database
The National Pollutant Inventory (NPI) reports on pollutant emissions from industry and diffuse sources. The location of pollutant sources is also provided.
Industrial facilities annually estimate their NPI pollutant emissions and diffuse emissions are determined by state and territory environment agencies. The 90 NPI substances span a wide range of toxicities. A small amount of a highly toxic substance may be of more concern than a larger emission of a less toxic substance.
The ultimate fate of NPI substances emitted to the environment impacts the effect they have on human health and the environment. The pollution exposure to humans and the environment cannot be determined solely from the NPI. Many additional factors determine whether a pollutant emission is felt as ground level pollution. Examples of additional factors are the:
Since NPI does not attempt to collect information about these additional factors, NPI data can only reflect pollutant emissions at the emission source.
The NPI holds pollutant emissions data reported by industrial facilities, and diffuse data determined by state and territory environment agencies. Industrial facilities are required to annually report emissions to the NPI if they exceed NPI reporting thresholds for ONE or more NPI substances. Diffuse emissions to air include sources such as: smaller facilities that are not required to report, transport (e.g. motor vehicles) and non-industrial (e.g. barbeques). Diffuse emissions to water include nutrients (total nitrogen and total phosphorus) emissions from water catchments due to different land use types.
Commonwealth, state and territory environment agencies have approved the techniques used to estimate emissions for the NPI. It is important to note that the accuracy of these techniques varies. For the diffuse data in particular, comparative analysis of the data may be misleading, because jurisdictions may have used different approved estimation techniques. Industrial facilities estimate pollutant emissions using techniques described in an industry NPI manual, or else otherwise approved.
NPI substances have a wide range of toxicities. A small emission may not necessarily be insignificant; for example, a small emission of a highly toxic substance may be of more concern than a larger emission of a substance of relatively lower toxicity. All emission amounts reported here have been rounded to two significant figures - totals may differ from the sum of the individual amounts on these reports because of this rounding. Some minor discrepancies may also occur with catchment and airshed data, particularly when queried at a fine spatial resolution such as a postcode. This is because these data are collected at varying spatial resolutions.
The large indicative Top Sources pie chart at the top of the location report is derived by converting each emission into proportional units - this provides an equal weighting for each substance, and does not consider any variation in hazard or possibility of exposure to substances.
The following worked example illustrates the calculation of equivalent percentage units in a queried region: If the total emission of Chromium (VI) compounds is 4.4kg, and motor vehicles emit 3.7kg, the proportional units for motor vehicles for Chromium (VI) compounds are calculated as (3.7/4.4) x 100 = 80.8. Similarly, if the total reported emission for Benzene is 30,000kg, and motor vehicles emit 28,000kg, the proportional units for motor vehicles for Benzene (28,000/30,000) x 100 = 94.1. This calculation is repeated for each substance/source combination, and the proportional units for a source are then summed to provide a total contribution of that source to the emission profile for this region.
| Substance | Total Emissions | Motor Vehicles | Repeat for all sources | |
|---|---|---|---|---|
| Emission | Proportional Emission Units [(Emission/Total)*100] |
. . . | ||
| Benzene | 30,000kg | 28,000kg | (28,000/30,000)x100=94.1 | . . . |
| Chromium (VI) compounds | 4.4kg | 3.7kg | (3.7/4.4)x100=80.8 | . . . |
| Repeat for all substances | . . . | . . . | . . . | . . . |
| Total proportional units | Sum for each source |
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