Figure 1.
Exclusion process to select healthy asymptomatic nonsmoking subjects, with fractional exhaled nitric oxide (FENO) median and range shown for each subgroup.
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.