Impact of pollution by particulate matter on emergency room admissions for respiratory causes in Chillán, Concepción, and Los Ángeles, Chile Objective: To determine the impact of air pollution on respiratory diseases in the districts of Chillán, Concepción and Los Ángeles, Chile between 2013 and 2017. Material and Methods: Generalized linear models (GLM) were estimated from daily data for emergency room admissions disaggregated by type and age range, concentrations of respirable particulate matter (PM 10) and fine particulate matter (PM 2.5), viral index, meteorological and seasonal variables. Results: A positive association is obtained between the analyzed contaminants and the number of emergency room admissions for respiratory causes, especially acute upper respiratory infection (URI) and acute bronchitis / bronchiolitis in Chillán, acute URI in Concepción, and also, acute URI, Influenza and obstructive bronchial crisis in Los Angeles. Conclusions: The increase in the total number of emergency room admissions is approximately 18,695 per year for every 1 μg / m 3 increase in PM concentrations.