The approaches used by the company’s businesses in reporting emissions data for greenhouse gases and other compounds are selected from combinations of the following principles that are listed in order
of accuracy. 

• Undertake continuous emission monitoring, and with measured exhaust gas flow, compute instantaneous mass emission rate and integrate over the reporting period.
• Undertake periodic monitoring of exhaust gas flow and composition and estimate mass emission over the reporting period using plant operating records.
• Estimate emissions using a mass balance and process flow knowledge.
• Estimate emissions using factors provided by the manufacturer’s specifications, local regulatory authority, AP-42, API Compendium or other industry standard.

Businesses are assisted in moving to more accurate methodologies, which may result in variances due to improved data quality from year to year.