"Cero" is a documentary that tries to expose what is the chemical pole of the city of Huelva located on Fco. Montenegro Ave., so close to the urban center in Spain. How it transformed the city at the infrastructure level and socio-economically, as well as affecting its environment due to the levels of pollution it produces, both in the environment and in people's health. Through contrasted information from several studies and interviews with representatives of local entities that talk about such circumstances. Made by Javier Vila García, Javier López Martín and Gonzalo del Campo Ladrero.