Measuring nitrous oxide in dental clinics: evaluating agreement between three types of nitrous oxide samplers

Objective: The objective of this study was to determine the agreement between a Miran SapphIRe infrared ambient analyzer, traditional passive dosimeter badges (badges), and thermal desorption tubes (TD tubes) during nitrous oxide (N 2 O) sampling in Indian Health Service (IHS) dental clinics.  Also, to determine if there is a statistically significant difference in the placement of the sampling device on the dominant and non-dominant side. Good agreement would be ± 15% of the Miran SapphIRe and could offer evidence for the TD tubes as being a potential alternative for future passive sampling of N 2 O. Methods: Passive sampling and direct-reading measurements were taken at three separate IHS dental clinic regions in the breathing zone of six dentists during dental procedures where N 2 O was used as the anesthetic throughout the IHS. Twenty-four sample sets were collected, each consisting of one TWA  Miran SapphIRe, two badge, and three TD tube concentration measurements. A paired t-test was used to compare dominant vs. non-dominant sides. A repeated measures Analysis of Variance test was performed to identify statistically significant differences between the three sampling devices.  The Bland-Altman method was used to investigate the level of agreement between the methods. Results: The t-test for the dominant vs. non-dominant resulted on p<. 05 for the badges and p>. 05 for the TD tubes. All devices proved to be significantly different when compared on the dominant side of the dentist p<.05 . However, when the Miran SapphIRe was compared to the non-dominant side the badge was found to not be statistically different p >.05. When plotted, both the badge and the tube failed to meet terms set forth for good agreement ±15%. Conclusion: The Miran SapphIRe may have played a role in altering the concentration of the badge and TD tube on the dominant side. However, neither of the passive samplers met the pre-defined Level of Agreement (+ 15%) acceptable to IHS for either the dominant or non-dominant sides. Thermal Desorption Tubes may be a good alternative to the conventional passive dosimeter badge as they were closer in agreement to the Miran SapphIRe than the conventional badge regardless of which side they were placed.