Nitrous Oxide Exposure Among Dental Personnel and Comparison of Active and Passive Sampling Techniques

This study measured dental personnel's exposure to nitrous oxide during dental procedures to compare exposures to occupational exposure limits, exposures between similar exposure groups, and results between passive and active sampling methods. Forty-one paired samples were collected using the Thermo Scientific™ Miran SapphIRe portable analyzer and the Advanced Chemical Sensor™ N-10 Passive Badge. Results were compared to the American Conference of Governmental Industrial Hygienists nitrous oxide 250 parts per million by volume (p.p.m.v) excursion limit and 50 p.p.m.v 8-h threshold limit values. Similar exposure groups were determined by job title for dentists and dental assistants across six dental clinics. An independent t-test was used to determine if there was a mean difference between exposures for similar exposure groups. A Bland-Altman analysis was used to assess level of agreement between the two methods. Results over the 250 p.p.m.v excursion limit were identified in 21 of 41 (51%) paired procedures. Two passive 8-h threshold limit value-time weighted averages were over the 50 p.p.m.v occupational exposure limit, one for each similar exposure group. There was no significant difference between similar exposure group concentrations using either sampling method (Miran, P = 0.071; passive badge, P = 0.106). However, the sampling results revealed dentists had higher exposures than assistants 81-86% of the time. The Bland-Altman analysis revealed the direct reading instrument and passive sampling methods differed by >25%. However, unexpectedly, the passive sampling method generally produced higher nitrous oxide results compared to the direct reading instrument sampling method. This study suggests nitrous oxide remains a serious exposure concern for both short-term high-intensity exposures and longer term 8-h exposures. Greater nitrous oxide exposures among dentists compared to dental assistants allow for prioritizing control measures between similar exposure groups. Both sampling methods provide valuable worker exposure information, with the direct reading instrument monitoring providing a larger range for short-term exposures and passive sampling providing a less invasive monitoring option.