Nitrogen oxides (NOX), sulfur oxides (SOX), and other significant air emissions (G4-EN21) Methodology

In 2018, the GRI G4 Sustainability Reporting Guidelines were superseded by the GRI Sustainability Reporting Standards (GRI standards). This is the methodology for G4-EN21, which has been superseded by GRI 305-7. The new GRI 305-7 metrics can be found here:

About

This metric is based on the Global Reporting Initiative (GRI) G4 Guidelines. It covers one of the reporting requirements of Indicator G4-EN21 – ‘NOx, SOx and other significant air emissions’. Other pollutants included in this indicator are Hazardous air pollutant (HAP), Persistent organic pollutants (POP), Volatile organic compounds (VOC), Particulate matter (PM), and other standard categories of air emissions identified in relevant regulations.

Air pollutants have adverse effects on climate, ecosystems, air quality, habitats, agriculture, and human and animal health. Deterioration of air quality, acidification, forest degradation, and public health concerns have led to local and international regulations to control air emissions. Reductions in regulated pollutants lead to improved health conditions for workers and neighbouring communities. Reductions, or performance beyond compliance, can enhance relations with affected communities and workers, and the ability to maintain or expand operations. In regions with emission caps, the volume of emissions also has direct cost implications.

This Indicator can also measure the scale of the organization’s air emissions and demonstrate the relative size and importance of these emissions compared with those of other organizations.

Methodology

These metrics look for the number of metric tonnes of significant air emissions produced by the company, including: Nitrogen oxide (NOx) emissions, Sulfur Oxide (SOx) emissions, Hazardous Air Pollutant (HAP) emissions, Particulate Matter (PM) emissions, Volatile Organic Compounds (VOC) emissions, Persistent Organic Pollutant (POP) emissions.

For WikiRate researchers:

Companies who align reports to GRI’s Sustainability Reporting Standards often include a GRI Content Index or Annex where GRI disclosures, with GRI codes, are listed.

Use the GRI Index, CTRL F, Command F or search button on source preview to search for this index and metrics within the report
Use G4 codes, G3 codes or keywords to quickly find values, keeping in mind that some companies report on the metric using different terms, e.g. G4-EN21 or EN21, mono-nitrogen oxides or NOx
Always check the metric question and methodology for the unit of measure or currency - researchers may need to carry out calculations or conversions before entering the final metric value
Add comments documenting exactly where within the source you found the information (page number) and include details of simple or complex calculations or conversions made to determine the metric value
If you are unable to locate a metric value in a source you can search for additional sources where the data is available and add a new source

Further guidance on how to research values for GRI-based metrics is available here, including detailed guidance on adding, editing and Checking metric values.

Global Reporting Initiative compliance guidance for companies:

To calculate emissions - G4-EN21-a:

Identify significant pollutants emitted by the organization and sources of significant air emissions release to the environment.
Calculate the amount of emissions released to the environment.

Organizations reporting on this Indicator should include the following information requirements as a comment to the metric value:

G4-EN21-b: Standards, methodologies, and assumptions used.
G4-EN21-c: Source of the emission factors used.