Global Reporting Initiative+NOx emissions (G4-EN21-a)

NOx emissions (G4-EN21-a)

How many metric tonnes of mono-nitrogen oxides (NOx) does the company emit?

Metric value
Companies Values
NRG Energy
2014 = 81.9M Tonnes
Hyundai Steel
2013 = 5.31M Tonnes
2016 = 3.65M Tonnes
Formosa Plastics
2014 = 2.84M Tonnes
Johnson Controls
2014 = 439,497 Tonnes
2015 = 317,314 Tonnes
2014 = 299,285 Tonnes
2016 = 262,000 Tonnes
2017 = 234,644 Tonnes
China Ocean Shipping Group - COSCO
2015 = 216,921.9 Tonnes
2014 = 207,621 Tonnes
2014 = 153,620 Tonnes
Royal Dutch Shell plc
2016 = 122,000 Tonnes
2014 = 89,916 Tonnes
2014 = 87,419 Tonnes
Cathay Pacific Airways
2014 = 80,946 Tonnes
CN Railway
2014 = 78,320 Tonnes
Duke Energy
2015 = 78,000 Tonnes
BHP Billiton
2017 = 73,700 Tonnes
Vina Concha y Toro
2015 = 71,285 Tonnes

Export: csv / json

Designed By
Metric Type
Research Policy
Community Assessed
Report Type
Corporate Social Responsibility Report
Value Type


This metric is based on the Global Reporting Initiative (GRI) G4 Guidelines. It covers one of the reporting requirements of Indicator G4-EN21-a – ‘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.


This metric is asking for the number of metric tonnes of mono-nitrogen oxides (NOx) produced by the company:

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 NOx emissions - G4-EN21-a:

  • ​Identify significant NOx pollutants emitted by the organization and sources of significant air emissions release to the environment.

  • Calculate the amount of NOx 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.

Bulk Import