OPS 50: Air pollution and health care utilization, Room 117, Floor 1, August 28, 2019, 10:30 AM - 12:00 PM An epidemiological research was conducted to establish the association between exposure to particular matter less than 2.5 diameters (PM2.5), and daily cases of respiratory disease (acute infection in the upper and lower respiratory tract) in vulnerable populations (under 5 years of age and 65 years and older) in the 10 municipalities of Aburra Valley region in Antioquia (Colombia) between 2008 and 2015. For each municipalities, the data was collected from the individual records of health service provision, time series analyzes were performed with generalized additive models (GAM) of Poisson regression. The findings were consolidated from meta-analysis supported in random effects models. In six of the 10 municipalities evidences of the shor-term effects of PM2.5 on the incidents of respiratory disease in the two age groups were found. In children under 5 years the consolidated effects show gradients for the single lag models and for the distributed lag models; the increase of the daily concentration of 10 µg/m3 of PM2.5 increased in 9.1% the cases of respiratory disease in Lag 1; the accumulated exposure during the first 3 days and during 15 days was related to respective increases of 12.6% and 19.4%. In adults aged 65 and over the effects were lower than those observed in the group of children, the increase of the daily concentration of 10 µg/m3 of PM2.5 increased in 4.2% the cases of respiratory disease. The accumulated exposure during 3-day was associated with increases of 2.9%, however the effect is reduced to 1.2% for accumulated lags of 7 days and diluted for cumulative exposure of 15 days, period for which the relative risk is not statistically significant. The results of this multicity analysis show the health effect of PM2.5 on respiratory morbidity of vulnerable population with greater association in children under 5 years.