The present invention is a method and system for producing a set of ratings for out-of-home media based on the measurement of behavior patterns and demographics of the people in a digital media network. A valve controls the release of the gas. The present invention contemplates, in a most preferred embodiment, a method for the prophylaxis andor treatment of psoriasis. A rack system may also include a monitoring system that includes at least one sensor in communication with a exhaust manifold of a cage that provides information to a controller that communicates cage conditions to a user via a graphic user interface. A nitric oxide delivery system may be used to generate therapeutic gas including nitric oxide for use in delivering the therapeutic gas to a mammal.