There are different in vivo and in vitro methods that are used to study pulmonary toxicity of various chemicals including PSP. In vivo, test substances are generally administered mainly by inhalation of aerosolised material or by direct intratracheal instillation of suspended material into the lungs of rodents. Other methods e.g. “pharyngeal aspiration” or “endotracheal respiration” have been applied by a few laboratories for mechanistic examinations, are not widespread yet. In vitro, there are quite a few cell lines or multi-culture models available. In the following Section the major methods and their pros and contras are summarised.