In the last 30 years, the Metropolitan Zone of Guadalajara (ZMG) has experienced a quick urban and industrial growth, situation which results in high rates of pollution and poor air quality harmful to the health of the population. The main purpose of this work was to analyze the SO2 and NO2 in the air, as well as ions H+, SO 4-2 and NO3- during the wet season of 2005. Results of the network of monitoring stations showed significant acidity in north-northwest and southeast of the study area. The maximum concentrations of SO 4-2 occurred in southeast and south, while the maximum NO3- was found in the south. Maximum levels of SO2 and NO2 occurred in the dry season, but it decreased in wet season. The higher frequency about acidity produced by NO2 is caused by mobile sources as the primary indicator.