The present invention provides a method for treating a disease in a human subject in need thereof, wherein the disease is selected from the group consisting of inflammation, bronchiolitis and cystic fibrosis, and wherein the method comprises repeatedly administering to the human subject a gas mixture comprising nitric oxide at a concentration from about 144 to about 176 ppm for a first period of time, followed by a gas mixture containing no nitric oxide for a second period of time, wherein the administration is repeated for a time sufficient to: a) reduce the level of at least one inflammatory biomarker in the human subject when compared to the level of the inflammatory biomarker prior to the administration； b) reduce the microbial density by 1 to 2 log units as measured by colony forming units in the human subject when compared to the microbial density prior to the administration； or c) a combination thereof.
