The research analyses air pollution policies for Mexico City. Based on the existing sociological literature, particularly on those authors that analyse the social construction of environmental problems. This thesis pretends to contribute to this field of knowledge. It assumes the relevance of the social dimension of environment and analyses its ideological and political dimensions. The main purpose of the research is to prove that air pollution is not only a technical problem but also a socially constructed one. There is a chapter in the thesis that demonstrates that air pollution programmes for Mexico City during the last two decades, are concentrated on addressing the physical, chemical and technical aspects, but lack an appropriate social approach, and this is fundamental for the efficacy of the programmes. The thesis also shows that the air pollution problem in Mexico City is socially defined. Its ideological and political dimension can be analysed in the contrasting and debated way that air pollution is perceived and conceptualised by different social actors. The thesis shows that this diversity of social actors and air pollution constructions are only incorporated in the official programmes to legitimise them, because they are not taken into account in the actual implementation of solutions to air pollution problems. The thesis includes, as a starting point, a general description of the air pollution problem in Mexico City, presenting the main data on its magnitude. It also contains a section describing the main existing findings on the health consequences of air pollution for Mexico City's inhabitants. Both aspects constitute the general background of the problem.