An evaluation of a passive nitrous oxide monitor.

Exposure limits to waste nitrous oxide (N2O) in dental operatories have been established by the National Institute for Occupational Safety and Health (NIOSH) at 25 ppm (average per period of administration) and by the American Conference of Governmental Industrial Hygienist (ACGIH average should prevent increased risk of spontaneous abortion and significant decrements in psychomotor and cognitive functions or other adverse health effects. Dentists and assistants can measure their personal exposure with clip-on devices called passive monitors. Using passive diffusion, the monitor collects N2O through its sampling face when exposed. After exposure, the monitors are analyzed by thermal desorption, and an average exposure value in ppm is calculated based on the length of time the badge was exposed. One such passive monitor, the Vapor-Trak N2O badge, was evaluated for its ability to accurately measure N2O exposures commonly found in dental office settings. Eighteen side-by-side area sampling runs were conducted in two dental offices which used N2O at least 15 hours/week and in a laboratory enclosure. Thirty-five Vapor-Trak badges and a Miran 1B2 portable infrared spectrophotometer (PIS) were used to measure N2O exposures ranging from 0 to 13000 ppm. Exposures of 100 ppm in waiting areas/hallways and 100 â€" 1300 ppm in operatories were not uncommon. Carbon dioxide (CO2), temperature, and humidity levels were also measured. For each sampling run, the PIS result was considered the true N2O exposure and regression analysis between badge and PIS results indicated the accuracy of the badge over various TWA intervals between 0 to 1372 ppm. In the laboratory and in the dental office, the Vapor-Trak badge exceeded the (+25%) OSHA accuracy requirements for measuring nitrous oxide exposure, at the NIOSH Recommended Exposure Limit (REL) of 25 ppm and the ACGIH Threshold Limit Value (TLV) of 50 ppm and for all badge results up to 108 ppm. Above 108 ppm, badge results were not as accurate, but accurate enough to indicate overexposure. The Vapoar-Trak nitrous oxide monitor was found to sample consistently at any concentration between 0 and 1372 ppm (5.9% coefficient of variation between badges measuring the same concentration). Thus, Vapor-Trak nitrous oxide monitor is a simple and effective clip-on device for measuring breathing air concentrations of nitrous oxide in dental offices. Any result over 50 ppm should trigger controls to reduce the nitrous oxide exposure below the