A study of mine air quality was conducted using the latest advanced continuous monitoring instruments. An overview of the various interacting variables in the mine that affect air quality is presented. One effort involves the evaluation of portable instruments, the development of measurement techniques, sample analysis procedures and computer programs for statistical analysis of measurement data, and the application of the instruments and techniques to the measurement of the concentrations of CO, co2, no, NO2, and particulate matter in a lead and a copper underground mine. A second effort involves the first application of the mine air monitoring laboratory (maml), a mobile trailer containing laboratory- type instruments, sampling, and data systems for the measurement of CO, co2, no, NO2, and particulate matter. The data from the maml for blasting and for operating diesel equipment are analyzed and presented in various plots.