Inhaled nitric oxide is currently administered in pediatrical and surgical intensive care units and could be an additional source of contamination of the indoor environment. Study found that inhaled nitric oxide therapy at doses up to 40ppm does not appear to pose a risk of excessive occupational exposure to nitric oxide (NO) or nitrogen dioxide (NO2) to healthcare workers during the routine delivery of critical care nursing in typical ICU setting. The NO levels of ICU environment were more dependent on traffic, air pressure and wind than on the treatment set-up. Personal exposure levels could be affected by changes in the NO treatment protocol, the concentrations of nitric oxide as well as oxygen, delivery method and the characteristics of treatment room. Providing adequate ventilation in the NO treatment room and avoid release the waste gas can control environment exposures.