We feel this is a great resource when studying or measuring industrial or atmospheric pollution!
US EPA Air Pollution Training Institute provides information to operators and inspectors of air pollution sources, compliance equipment, and methodologies. It is fundamental in understanding US Code of Federal Regulations (CFR) Methods.
The US EPA Emissions Measurement Center covers all of the US EPA Test Method and Performance Specifications.
It should be understood that EPA methods follow prerequisite methodology, for instance Methods 1-4 are part of Method 5. You must read and follow the method correctly in order for the calculations and data to tally.