Data quality: National Pollutant Release Inventory

The Quality Control Process and Ensuring Data Quality

Overview 

This guide gives a brief overview of the NPRI quality control process and provides information about the steps taken to ensure the quality of its data.

The NPRI ensures high quality information is made publicly available for its users by performing the quality control process annually.

Useful resources

To learn more about NPRI data, see Canada’s National Pollutant Release Inventory: data highlights.

Quality Control Process 

Every year, businesses, institutions and other facilities across Canada must report their releases and disposals of pollutants to the NPRI by the annual deadline.

Before the data is published online, the NPRI team performs quality control checks on the reports submitted by facilities for inaccuracies and reporting errors. If we find errors, we may contact or visit facilities to verify or correct information.

Quality Control Process

Timeline:

  • Starts shortly after the June 1 reporting deadline
  • Analysis is done by:
    • NPRI staff
    • other experts in Environment and Climate Change Canada
    • industry associations
  • Facilities are also encouraged to check their own data:
    • Raw data is posted online soon after the reporting deadline to allow for public data review.

We confirm this information about facilities:

  • Latitude and longitude
  • NPRI ID
  • If the organization reported for all of its facilities
  • Sector classification codes: designed to provide common definitions of the industrial structure and a common statistical framework to facilitate analysis

We ask these questions about the data:

  • Is the data reported in the right units?
  • Is the data reported in the right place?
  • Do the values fall within expected ranges?
  • Is the data consistent with previous years’ reports?
  • Is the data consistent with data from other sources?
  • Are all releases, disposals and transfers of reportable substances included?
  • Did the facility provide information that helps explain the reported data?
  • Are the top facilities (by substance and source) consistent from year to year?
Results of quality control for the 2018 reviewed NPRI data: 
  • Some data was reported in incorrect units or with decimal errors (such as reporting in kilograms instead of tonnes).
  • Sometimes a substance or quantity was omitted.
  • Some facilities used incorrect reference data or assumptions. For example, some reports include the total amount of a substance used at the facility, rather than the quantity released.

To learn more about the 2018 NPRI data, see Canada’s National Pollutant Release Inventory: data highlights 2018.

Data Quality Management Framework 

The NPRI Data Quality Management Framework outlined below ensures high quality information that meets the needs of data users. It defines data quality in terms of seven elements. Below are the definitions and activities associated with those elements.

Relevance: data meets the needs of users

  • Consult users about data needs, changes to reporting requirements, and tools to access, use and interpret data
  • Keep NPRI substance list relevant to program and departmental activities
  • Website usage statistics inform the development of NPRI web content
  • Data users may propose changes to reporting requirements

Accuracy: data describes what it measures

  • NPRI reviews data for inconsistencies and errors
  • NPRI contacts facilities to verify and correct reports
  • Toolbox helps facilities submit the correct information

Reliability: data can be combined confidently with other information

  • Verify that facilities report releases and transfers correctly
  • Review and validate latitude and longitude coordinates so that mapping software can locate facilities
  • Analyze ways to combine data with other datasets

Completeness: expected data is described

  • Analyze data to verify that reports are complete
  • Plan compliance activities based on changes to reporting requirements
  • Refer non-compliant facilities to Environment and Climate Change Canada’s (ECCC) Enforcement Branch

Understandability: supplementary information and metadata are available

Accessibility: data is made available in a number of formats

Timeliness: data is published on schedule

Section 50 of the Canadian Environmental Protection Act, 1999 (CEPA 1999) requires ECCC to publish NPRI data. The department has adopted these service standards for NPRI:

  • preliminary data from facilities is published within one month of the reporting deadline
  • a reviewed dataset is published in various formats within six months of the reporting deadline

Note that the Data Quality Management Framework presented above is not static. Over time, the NPRI data quality activities undertaken by ECCC may vary to reflect the evolution of the NPRI and the needs of data users. Activities may be adjusted, discontinued or added to maintain a balance between the various dimensions of quality, and to address new challenges and opportunities that may be encountered.

Contact us 

Contact the NPRI if you think:

  • there are errors in your data
  • you need to update or edit past reports
  • you need help for your data projects
  • you have any other questions

You can contact us at:

National Pollutant Release Inventory
Environment and Climate Change Canada
5th Floor, Place Vincent Massey
351 St-Joseph Boulevard
Gatineau, Québec K1A 0H3
Telephone: 1-877-877-8375
E-mail: inrp-npri@ec.gc.ca

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