In an effort to determine the availability of portable, direct reading carbon-monoxide (630080) meters with a range of approximately 10 to 500 parts per million (ppm), a market survey was conducted. Six companies were asked to submit meters for evaluation; the performance characteristics of the submitted meters were studied. Of the meters evaluated (Bullard, Dackel, Ecolyzer, EnMet, MSA, Wilks), the Ecolyzer most closely satisfied all the evaluation criteria and guidelines. It is portable, operates from an internal battery pack for many hours, is a direct reading meter and has a dual range readout that covers a range from 0 to 600ppm. The MSA meter was ranked second with a 0 to 500ppm readout and portability. The MSA, however, lacks a recorder output and has a meter resolution less than the Ecolyzer's. The Bullard meter provided excellent portability and a long lived sensor. The meter readout is logarithmic and does not provide for good resolution on the high end of its 0 to 300ppm range. The EnMet is very small, portable, and has a direct readout. It is a prototype and has a limited range of 0 to 100ppm and is relatively insensitive to carbon- monoxide levels below 20ppm. The Dackel is also a prototype, very small and portable with a readout from 50 to 300ppm on a logarithmic scale. The Wilks meter is an excellent instrument but it cannot be easily compared to the other meters examined. It is not portable in the sense that the others are and it is not a carbon-monoxide meter. It is an infrared gas analyzer and it can be calibrated to read carbon-monoxide concentrations in the 0 to 500ppm range.