Evaluation of a Personal Data Logging Monitor for Carbon Monoxide

Abstract

Personal data logging monitors provide real-time measurement of pollutants and have the ability to store data over an extended period of time. As such, they can be used to provide warning to workers that high concentrations are present, as well as allowing the assessment of long-term worker exposure. The performance characteristics of these monitors are fundamental to the determination of the accuracy of the warning and exposure measurement data. In this study, the performance characteristics of one type of personal carbon monoxide (CO) data logger (Draeger 190) were evaluated.

The monitor displayed linear response over the concentration range 0 to 950 ppm. The 12-hour zero drift for the monitor was less than 1 ppm, and the 12-hour span drift was less than 2 percent at 100 ppm. The monitor showed less than 3 percent variation in response for CO concentrations of 20 ppm to 100 ppm when exposed to CO concentrations in a repeated cycle. The long-term response stability showed a coefficient of variation of 9 percent at 57 ppm for response data taken over a 3-month period, where the monitor was calibrated at a 30-day interval. The monitor was found to reach 90 percent of final response within 20 seconds. Changes in humidity did not affect monitor response, while response did increase with temperature over the range of 0°C to 40°C. The temperature response varied between monitors and for different concentration ranges. Some interferences (nitric oxide, nitrogen dioxide, hydrogen sulfide, and sulfur dioxide) were completely removed by the CO-specific filters on the monitors, while other interferences (acetylene, ethylene, and hydrogen) were not. Also, the response to acetylene was affected by the condition of the CO-specific filter. The monitor also responded to hair spray when it was sprayed near the monitor. The hair spray produced a full scale response if it was sprayed directly on the monitor.