Portable Emissions Measurement Systems (PEMS)

Portable Emissions Measurement Systems (PEMS) are mobile emissions-testing devices used to measure pollutants from vehicles and engines during real-world operation rather than under laboratory conditions. Installed directly on vehicles, PEMS combine gas analyzers, exhaust flow meters, GPS, and environmental sensors to monitor GHG emissions such as nitrogen oxides (NOx), carbon dioxide (CO₂), carbon monoxide (CO), and particulate matter in real time. PEMS are widely used in Real Driving Emissions (RDE) testing and vehicle regulatory compliance to help verify that emissions standards are met during actual road use.