A method of monitoring an air atmosphere for a harmful biological or chemical agent includes providing a plurality of mammalian respiratory airway epithelial cells borne on a porous support; contacting the porous support with a cell nutrient medium and with air by positioning said porous support at an air-liquid interface between the cell nutrient liquid and the air; sampling the air atmosphere to thereby create an air flow over the air-liquid interface so that the respiratory epithelial cells borne on the porous silicone support are contacted by the sampled air; and monitoring the respiratory epithelial cells for at least one physiological parameter indicating the cells have been exposed to the harmful agent.