The Bureau of Mines, U.S. Department of the Interior, conducts research to reduce exposure of miners to exhaust emissions of diesel-powered mining equipment. Conventional sampling and instrumentation techniques used to measure emissions over a research duty cycle distort the signal generated by time variation of the concentration of gases in the exhaust. Delays up to 30 sec, effective integration times up to 2.9 sec, and dispersions up to 1.4 sec are observed. This paper reports numerical techniques that make it possible to infer the actual variation of concentration in the exhaust on a time scale of about 1 sec. These techniques are used to evaluate the product of concentration and flow to yield accurate total gaseous emission during a test.