The interpretation of the reactions that air pollution produces on human health is based on studies of two classes, toxicological and epidemiological ones. Both types of studies are considered complementary

- Experimental studies, on man or animals, are those where the concentration, duration and conditions of the exhibition are controlled by the investigator. Their main advantage, in fact, resides in the control of the exhibition conditions. As inconvenience we have the fact of an artificial situation, since a reduced number of pollutants is used, in ideal situation, to big doses and in special environmental circumstances. Also, the populations with whom it is experienced may not be not very representative.

- Epidemiological studies, refer to the observation of the events that are developed in the human populations under natural conditions, circumstance in which their most significant advantage resides.