A review of mine air pollutant standards and the important pollutants to control in underground mines using diesel powered equipment is presented. The underground Mine Air Quality Laboratory instrumentation is discussed. This includes the Mine Air Monitoring Laboratory (MAML) and the instrumented Load Haul Dump (LHD) vehicle. The MAML measures CO, NO2, NO, CO2, particulate and temperatures while the LHD instrumentation measures and records engine speed, rack position (fuel rate), vehicle speed, CO2 concentration, exhaust temperature and operating mode with transducers and a Sea Data Corporation data logging and reader system.The mine LHD cycle data are related to the EPA 13 mode cycle data. Engine and aftertreatment emission control methods are reviewed including recent laboratory NO, NO2, sulfate and particulate data for a monolith catalyst.Maintenance of the LHD vehicle by engine subsystems in relation to component effects on emissions is presented. The design of a tailpipe Emissions Measurement Appartus (EMA) for underground exhaust measurements of CO, CO2, NO, NO2 and particulate under loaded conditions is discussed including the method of loading the engine. Emissions data for several vehicles in two underground mines are given. The EMA is envisioned as a quality control measurement method to assist mine maintenance personnel in maintaining low emissions vehicles.CO and CO2 data from the MAQL are presented for several ventilation control methods: a fan, a fan with vent tubing, Fume Diluters and two exhaust system designs. The modified exhaust system involved a rearward directed exhaust system pointed at a 20-30° angle towards the roof. This system was shown to enhance the natural ventilation in that the cool mine air flowed into the drift at the bottom of the drift and the diluted exhaust gaeses flowed out of the drift at the top. The modified system was shown to reduce pollutant concentrations by 50% over the standard system which was directed out the side of the vehicle at the floor level.