A survey of nitrous oxide levels in dental offices.

The nitrous oxide (N2O) levels in 23 dental offices located in Philadelphia and surrounding suburbs were measured during an 8-hr working day using an infrared spectrophotometer. Results indicate that high concentrations of N2O exist in the dental workplace and exceed NIOSH recommended values by over 40%. Mean ambient N2O levels for all 23 dental offices was 35.7 ppm. There was no significant difference in the concentration of N2O in small vs. larger dental offices. However, individuals in the large offices were exposed to high levels of the gas for shorter time periods. While only 4 of the 23 dental offices possessed scavenging equipment, scavenging systems appeared to make no significant difference in ambient N2O levels in the dental workplace.