The effects of air pollution on respiratory health in susceptible populations: a multilevel study in Bucaramanga, Colombia Efectos de la contaminación atmosférica en la salud respiratoria de población susceptible: un estudio multinivel en Bucaramanga, Colombia

We conducted a cohort study to investigate the association between exposure to three different levels of outdoor air pollution and incidence of respiratory symptoms in a population with chronic cardiovascular and respiratory disease. We accompanied 756 participants for a period of six months through the maintenance of a daily record of symptoms and clinic visits. The symptoms with highest incidence rates were sneezing and hacking cough. Multivariate analysis showed that incidence of total symptoms was 60% and 74% lower in areas with medium and low levels of pollution compared to areas with high levels of pollution. These results suggest that negative respiratory effects occur at concentrations of particulate matter PM10 > 60ug/m3. Respiratory Signs and Symptoms; Chronic Disease; Air Pollution; Population Introduction Air pollution is a well known environmental determinant of health, especially among urban populations 1. This association is probably due to growing industrialization and an increase in the use of motor vehicles. The effects of this process have been shown not only in developed countries but also in small and large cities in the developing world 2. Several studies have demonstrated the association between air pollution and respiratory and cardiovascular diseases 3,4,5,6. Increased concentrations of particulate matter with an aerodynamic diameter of less than 10μg/m3 (PM10) is associated with an acute increase in emergency room visits, hospital admissions, respiratory symptoms, mortality rate due to respiratory and cardiovascular disease and restricted activity days due to morbidity 7,8. Children and older or chronically sick individuals are most susceptible to the negative effects of air pollution 9,10. This finding is explained biologically by an immature or low immunological system response and particulate matter entering the respiratory system is expected to have a more acute respiratory effect in susceptible people 11. Bucaramanga is a city with approximately 600,000 inhabitants located 980 meters above sea level in the northwest of Colombia. Average annual temperature is 22.1°C (18.8°C to 30°C) ARTIGO ARTICLE Rodriguez-Villamizar LA et al. 750 Cad. Saúde Pública, Rio de Janeiro, 28(4):749-757, abr, 2012 and average annual humidity is 83.9%. The city’s air quality monitoring network has shown PM10 concentrations that are higher than the locallyadjusted national limits 12 (maximum limit of 134μg/m3 24 hours) and the international limits 13 (maximum limit of 150μg/m3 24 hours) in some areas. A recent study of children under seven years of age living in the city and exposed to high and low levels of PM10 concentrations did not find any association between exposure to PM10 and incidence of respiratory symptoms 14. However, most of the children studied were healthy and it is not known whether exposure to different levels of PM10 has an adverse effect on the city’s susceptible population considered as those individuals with a chronic cardiovascular or respiratory morbidity background. The aim of this study was to analyze the effects of exposure to three different levels of air pollution, measured in PM10 concentrations, on the respiratory health of Bucaramanga’s susceptible population. Materials and methods