RESPIRATORY SYMPTOMS AND COUGH REFLEX IN POPULATIONS EXPOSED TO DIFFERENT DEGREES OF POLLUTION

Background: Santiago is a city with a high degree of environmental pol lution caused by particulate matter and ozone, producing adverse effec ts in the respiratory system. Aim: To compare respiratory symptoms and cough reflex in adults from Santiago and from a rural area with low l evels of environmental pollution. Subjects and methods: One hundred tw enty six non smoker adults from Santiago and 116 from a rural area wit h low levels of pollution answered a respiratory symptom questionnaire . Of these 101 subjects from Santiago and 116 from the rural area inha led doubling concentrations of capsaicin from 0.5 to 500 mu M or until five coughs were elicited. The lowest concentration eliciting 2 or mo re coughs (CD2) or 5 or more coughs (CD5) was recorded. Levels of envi ronmental particulate matter were also recorded in both locations. Res ults: Levels of particulate matter were 102 +/- 41 and 64 +/- 24 mu g/ m(3) in Santiago and the rural area respectively. People from Santiago had higher rates of throat clearing, cough and phlegm. CD2 geometric mean and confidence limits in Santiago and the rural area were 6.9 (5. 2 - 7.4) and 2.8 (2.7 - 2.39) respectively (p < 0.001). No differences in CD5 were observed between both locations. Multivariate analysis di sclosed the variable location (city) as the only independent predictor of respiratory symptom. Conclusions: The increased CD2 found in Santi ago suggests that the higher rates of respiratory symptoms related to air pollution can be associated to a decreased sensitivity of the coug h reflex.