Abstract: The invention provides a detector for detecting air components, e.g. contaminations, and in particular noxious or poisonous contaminations, which device comprises a housing in which an air pervious carrier containing a first reagent is arranged, this detector being adapted to draw air to be tested through said carrier so as to expose this reagent to the air, this reagent being influenced by the components to be detected, which carrier is to be contacted with a second reagent which, together with the first one, can bring about a color reaction depending on the fact whether the first reagent has been influenced or not.