This paper defines the index of environmental quality (ICA) as a latent variable determined by a group of factor that affects it in a positive and negative manner.Setting off from the hypothesis of non environmental homogenous pertaining to urban territory, and following the construction of a system of simple indicators and its application in larges city.The most influential factors in the determination of the ICA by each comuna are established as well.Consequently, important information is derived, which will enable the planner and environmental agent to prioritize the assignation of economic resources, not only in a differential way among comunas but for the sort of resources or environmental variables that most affect the quality of environment.