Archived: Air Pollutant Emission Inventory report: annex 2 - inventory development: part 1

A2.1 Overview of the compilation process

The process of compiling emission estimates for the Air Pollutant Emission Inventory (APEI) consists of developing in-house estimates, categorizing facility-reported data, and where necessary, reconciling the in-house estimates and the facility-reported data in a central database (Figure A2-1).

First, facility-reported data are compiled with the extraction of National Pollutant Release Inventory (NPRI) facility and emissions data from the verified NPRI database. New facilities are identified in the extracted data and classified among the APEI sector and subsector categories according to the nature of their activities. A quality control process is performed on the point source data prior to its inclusion in the APEI. A summary of this quality control process is presented in Chapter 4. A list of the facility-reported data is then produced and transferred to a central APEI database.

Figure A2-1: overview of the annual APEI compilation process

In-house estimates are based on documented estimation methodologies, periodically reviewed and updated through literature searches, the collection and analysis of recent emission factors and activity data, and comparisons with alternative sources of information. Improvements to methods or data are implemented as appropriate, and estimates may be recalculated for part of or across the entire time series. Updated estimates are calculated using new and/or updated activity data. Calculations are typically performed in spreadsheets or database-driven emission models.

The next step in the compilation process is the elimination of any double-counting of emissions between the in-house estimates and facility-reported data  by a process of reconciliation. Reconciliation of the in-house estimates with the facility-reported data is required for sectors or subsectors when both in-house and facility-reported estimates exist (Table A2-1). For 2016, reconciliation was performed for the asphalt paving industry and about 20 other source categories. More information on reconciliation is available in section A2.5.1.

The final steps in the compilation process involve aggregating all reconciled data in the central database to produce draft emissions summaries for quality assurance/control and consultation purposes. The final emissions database is also used to generate emissions tables and figures which in turn fulfill Canada’s international and domestic reporting obligations.

A2.2 In-house estimates

The compilation of in-house estimates relies on information such as production data or activity levels for each sector. Calculations of in-house estimates are based on the latest data available at the time of compilation. When possible, the data are updated the each year.

Table A2-1 lists the sectors and subsectors of the APEI for which emissions are based on in-house estimates and provides the activity data year on which the 2016 in-house estimate is based.  

The in-house emissions estimation methodologies and emission models used in Canada are generally based on those developed by the United States Environmental Protection Agency (U.S. EPA) adapted to utilize Canadian data, thereby accounting for differences in climate, fuels, technologies and practices. Methods used in Canada’s APEI are therefore generally consistent with those used in the United States or those recommended in the European emission inventory guidebook (EMEP/EEA 2013).

Tables A2-2 through A2-12 summarize, for each source category, the estimation methodologies for the entire time series. For each source category, these tables provide a short description of:

• the emission sources and pollutants covered
• the general inventory approach; and
• references for the activity data, emission factors and/or emission models

Table A2-1: 2016 Air Pollutant Emissions Inventory (APEI)

Notes

X: denotes yes

^a All facility-reported data were obtained from the NPRI Reporting Year 2016.

^b Facility-reported data consists of facilities located in Atlantic Canada. For other provinces, it consists of in-house estimates.

^c Facility-reported data consists of facilities located in Atlantic Canada and SO₂ emissions from Alberta's natural gas processing facilities.

^d In-house estimates for Wood Products were estimated by the Forestry Products group of the Environmental Stewardship Branch at ECCC. All other in-house estimates were estimated by PIRD.

^e Ammonia emissions from infant diapered waste, which were previously reported under Other Miscellaneous Sources, are now reported under the Human sector.

^f Emissions reported under Other Miscellaneous Sources are from breakage, transport and recycling of mercury-containing products. Products include: automotive mercury switches, batteries, dental amalgams, fluorescent lamps, fungicides, measurement and control devices, non-fluorescent lamps, switches and relays, thermometers, thermostats and tire balancers.

^g Emissions from Hg-containing products were calculated as a separate inventory. Emissions are reported under many sectors such as Iron and Steel Industries, Municipal Incineration, Human, Other Miscellaneous Sources and Landfills. All in-house estimates for Hg in product emissions continues to be estimated and reported under these sectors.