Abstract: A metallic air admittance valve has a tubular body with a valve chamber integral to one end of the tubular body. The valve chamber has a valve and an air inlet configured to permit the flow of air when the pressure within the valve is less than the pressure outside of the valve, but to prevent the flow of air when the pressure within the valve equals or exceeds the pressure outside of the valve. The tubular body and valve chamber are fabricated from metal and, therefore, do not emit noxious or toxic fumes when subjected to fire. Plumbing systems in commercial buildings may have metallic air admittance valves located within the plenum area of the building without presenting the risk of the distribution of toxic fumes throughout the building when the air admittance valve is subjected to fire.