Exhaled nitric oxide as a marker of adverse respiratory health effect in environmental disease.

The presence of, and the possibility to assay, nitric oxide (NO) in exhaled breath of humans caused a great deal of interest in relation to understanding the physiological and pathophysiological role of this molecule. Most studies have measured exhaled NO by chemiluminescence and detection depends on the photochemical reaction between NO and ozone generated in the analyzer. Here we discuss the role of exhaled NO as a physiological method to evaluate the effect of environmental changes on lower and upper airways in healthy subjects; particularly, its potential application as non invasive marker of the effect of outdoor and indoor air pollution on the respiratory tract.