Measuring nitrous oxide in dental clinics: evaluating agreement between three types of 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 dentists during procedures using N2O sedation. 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, badges had an upper Limit of Agreement (LOA) of 13 and lower LOA of 0.2. The TD tubes had upper LOA of 2.5 and lower LOA of 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 better alternative to the conventional passive dosimeter badge, as they displayed closer agreement to the Miran SapphIRe.