Research Program Area: Health & Exposure
Epidemiological studies have reported associations between ambient concentrations of nitrogen dioxide (NO2) and morbidity, but human exposure studies with ambient concentrations of NO2 have not shown significant effects. Since a significant concentration of nitric oxide (NO) is often present in ambient air, the epidemiological findings attributed to NO2 could be due to NO. This literature survey addressed whether an ambient air quality standard for NO was warranted, and/or whether there was evidence that inhalation of ambient NO has health effects that should be investigated further. While it is clear that NO is biologically active throughout the body, and that ambient NO could induce health effects, the review concludes that currently there is insufficient evidence to warrant an ambient air quality standard for NO. The review concludes that NO can be both beneficial and injurious, and suggests that ambient concentrations of NO could affect cardiopulmonary regulation, pulmonary inflammation, asthma and other inflammatory lung diseases, host defense, immune responses and platelet function. Suggested areas for further research include: (1) biochemical and/or cellular changes in the lungs indicative of pulmonary inflammation; (2) effects on asthma and other inflammatory diseases; (3) whether environmental NO is beneficial; (4) effects on platelet function; (5) effects on endogenous NO production; (6) effect on ventilation/perfusion (VA/Q) mismatching; and (7) the role of NO in epidemiological findings attributed to NO2, carbon monoxide (CO) and particulate matter (PM).
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
Stay involved, sign up with CARB's Research Email Distribution List