Research is being directed toward developing optimum methodology to control air quality in underground mines where diesel equipment is employed at the working face. Emphasis is primarily on instruments, measurement techniques, and field ambient concentration data. Mine evaluation of vehicle-mounted co2 monitoring prototypes and the development of a recording system that stores the co2 data in the form of a cumulative frequency distribution are described. Co, co2, no, NO2, and particulate matter measurements near diesel equipment in Colorado Westmoreland's Orchard Valley Mine are reported. Evaluations of the NO2 sampler, the particulate matter monitors, the oxides of nitrogen monitor, bag sampling for co2, the NO2 prototypes, and the hi-flow samplers are discussed. The state-of- development of the mine air monitoring laboratory (maml) and examples of its use are included. A punch tape data system, a thermocouple system, a fire extinguisher system, capability for 10 gaseous sample lines, and 2 particulate samples with a 10:1 dilution system have been added to the maml.