Field comparison of three nitrous oxide samplers

Objective: The primary objective of this study was to determine the agreement between a Miran SapphIRe infrared ambient analyzer, conventional passive dosimeter badges (badges), and thermal desorption tubes (TD tubes) during nitrous oxide (N2O) sampling in Indian Health Service (IHS) dental clinics.  Agreement of ± 15% between TD Tubes and the reference Miran SapphIRe could suggest the TD tubes as an alternative for future passive N2O sampling. Methods: Passive samples and direct-reading measurements were taken in the breathing zone of six dentists at five IHS dental clinics where N2O was used as the dental procedure anesthetic. Twenty-four sample sets were collected, each consisting of one TWA Miran SapphIRe measurement, two badges, and three TD tubes. A repeated measures Analysis of Variance (ANOVA) test was performed to identify statistically significant differences between the three sampling devices. The Bland-Altman method was used to investigate the specific level of agreement. Results: All devices had significantly different N2O concentrations (p<.05). When plotted, badge reported an upper Limit of Agreement (LOA) 13 and lower LOA 0.2 the TD tube reported upper LOA 2.5 and lower LOA 0.2. Conclusion: Neither of the passive samplers met the pre-defined Level of Agreement (± 15%) acceptable to IHS. However, TD tubes may be a good alternative to the conventional passive dosimeter badge, as they displayed closer agreement to the Miran SapphIRe.