Periodic (i.e. semi-annual) sampling is done of dental personnel, especially chair-side personnel exposed to nitrous oxide (e.g. with a diffusive sampler, such as a dosimeter or infrared spectrophotometer) Office personnel who are at higher risk of NO toxicity, to prevent this most sensitive test for nitrous oxide detection is Infrared spectrophotometer. Reference: Pediatric Dentistry by Nikhil Marwah 3rd ed, page no 250