 Portable emissions measurement system

A portable emissions measurement system (PEMS) is a vehicle emissions testing device that is small and light enough to be carried inside or moved with a motor vehicle that is being driven during testing, rather than on the stationary rollers of a dynamometer that only simulates real-world driving.Early examples of mobile vehicle emissions equipment were developed and marketed in the early 1990s by Warren Spring Laboratory UK during the early 1990s, which was used to measure on-road emissions as part of the UK Environment Research Program.