controlling exposures of workers to nitrous oxide (N2O) during the administration of anesthetic gas in medical, dental, and veterinary operatories. NIOSH concluded in 1977 that exposure to N2O causes decreases in mental performance, audiovisual ability, and manual dexterity [NIOSH 1977b]. A recent study of workers [Rowland et al. 1992] and several experimental animal studies [Corbett et al. 197...