A method of treating a human subject which is effected by intermittent breathing cycle-coordinated pulse delivery inhalation of gaseous nitric oxide at a concentration of at least 160 ppm, or at a load per cycle of 80 ppm-hour, is disclosed. The method can be utilized for treating a human subject suffering from, or prone to suffer from, a disease or disorder that is manifested in the respiratory tract, or from a disease or disorder that can be treated via the respiratory tract. The disclosed method can be effected while monitoring one or more of on-site and off-site parameters such as vital signs, methemoglobin levels, pulmonary function parameters, blood chemistry and hematological parameters, blood coagulation parameters, inflammatory marker levels, liver and kidney function parameters and vascular endothelial activation parameters, such that no substantial deviation from a baseline in seen in one or more of the monitored parameters.