We have Nitrous Oxide at several of our Dental sites for minimal sedation and we have a passive scavenging system. . We were surveyed by the Joint Commission and they said we need to provide testing of the room air where its being used. Looking at NFPA 99 I do not see anything in Ch 15 Dental Gas and Vacuum systems. We need to know the standard, frequency and levels required. Appreciate the assistance.