The fractional concentration of exhaled nitric oxide (Feno) is a useful indicator of airway inflammation in children and adults with asthma.
We determined the range of Feno concentrations and the factors affecting it in a large sample of healthy school children attending grades 4 through 6, in Windsor, ON, Canada.
Feno was measured in 657 children between 9.1 and 12.9 years of age. The range of Feno concentrations in healthy school children was 12.7 parts per billion (ppb) [95% confidence interval (CI), 11.8 to 13.7 ppb] in whites and 22.8 ppb [95% CI, 17.9 to 27.7 ppb] in Asian-Canadian children (p