The Nitrous Oxide Vapor Monitor from NevinLabs is either clipped to the clinician or placed in a specific room to be monitored. Once the data is recoded, it is mailed back to Nevin in the provided mailer. The amount of nitrous oxide vapor absorbed measured as a time-weighted average and the parts per million. In about a week, the user receives a report that indicates actual exposure in PPM along with practical methods to reduce exposure if it is too high. NIOSH limit 50 ppm in dental operatory. Single Badge.