Treatment of pulmonary disorders associated with hypoxemia and/or smooth muscle constriction and/or inflammation comprises administering into the lungs as a gas compound with an NO group which does not form NO₂/NO_x in the presence of oxygen or reactive oxygen species at body temperature. Treatment of cardiac and blood disorders, e.g., angina, myocardial infarction, heart failure, hypertension, sickle cell disease and clotting disorders, comprises administering into the lungs as a gas, a compound which reacts with cysteine in hemoglobin and/or dissolves in blood and has an NO group which is bound in said compound so that it does not form NO₂/NO_x in the presence of oxygen or reactive oxygen species at body temperature. Exemplary of the compound administered in each case is ethyl nitrite.