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What Stack Test Data Can Tell You Beyond Compliance Key Takeaways Stack test data can support more than a comparison against an emission limit. It can help facility teams evaluate equipment performance, control efficiency and emissions assumptions. Operating conditions provide essential context. Load, fuel, process rate, control settings and other conditions influence how test resultsRead more

One Engine, Multiple Rules: How JJJJ, ZZZZ, Air Permits and Testing Fit Together Key Takeaways Engine compliance begins with classification. Fuel, ignition type, horsepower, construction date, operating purpose and the facility’s hazardous air pollutant source classification can all affect applicable requirements. Subpart JJJJ and Subpart ZZZZ address different regulatory programs, and some engine categories useRead more

Particulate Matter Stack Testing: How EPA Methods 1 Through 5 Work Together Particulate matter stack testing is a coordinated measurement process. Before a testing team can determine how much particulate matter is leaving a stationary source, it must identify a representative sampling location, measure the movement and composition of the exhaust gas, account for moistureRead more

Frequently Asked Questions About Stack Emissions Testing Stack emissions testing gives facility teams measured data they can use to demonstrate compliance, evaluate equipment performance and make informed operating decisions. Because every source, permit and test program is different, successful testing begins well before a crew arrives on site. The following answers cover common questions aboutRead more

EPA has finalized a rule that rescinds the agency’s 2009 greenhouse gas endangerment and contribution findings and repeals federal greenhouse gas emission standards for vehicles and engines that were developed under Clean Air Act Section 202(a)(1). EPA frames this as a change in how it interprets its authority to regulate greenhouse gas emissions from newRead more

Stationary combustion turbine permitting is getting renewed attention as more facilities add on-site generation to support growth, reliability, and operational continuity. EPA’s January 2026 updates to the New Source Performance Standards (NSPS) for stationary combustion turbines reinforce a key point for owners and operators: combustion turbines are generally regulated as stationary sources and permitting obligationsRead more