Industries, regions, or other groups are issued emission permits which state their yearly emission allowance. Those that need to increase their emission allowance must buy credits from those who pollute less.
Companies must offer documentation that demonstrates they have not reached their accepted allowance of emissions and can receive credits which can be traded for economic incentives to companies which may need to exceed their allowance.
To do so requires accurate measurement and stringent documentation. ISO accredited calibration gas mixtures are used to ensure documented accuracy and traceability for use in this verification.