Pulmonary inflammation is a common pathological feature of a variety of diseases, of which successful therapy with currently available anti-inflammatory drugs is limited by resistance and adverse side effects. Using the ovalbumin-induced mouse allergic asthma model, the present study shows that treatments with pH modifiers, particularly simple acids such as acetate or hydrochloric acid, effectively depleted inflammatory cells in the lungs and blood as well as hyperplastic lung tissue cells while preserving the structure of the blood vessels and lung parenchyma. The acid treatments also suppressed mucus hypersecretion. These results demonstrated pH modifiers as a new class of broad-spectrum anti-inflammatory agents with anti-proliferation and mucus suppression activities.