Air pollution and hospitalization for venous thromboembolic disease in Chile.

Background: Ambient air pollution is a risk factor for stroke and myocardial infarction, possibly because of alterations in coagulation that influence the arterial circulation. Whether air pollution influences diseases associated with peripheral venous thrombogenesis remains largely unknown.

Objectives: To determine the association between air pollution and venous thromboembolic disease (VTE) in a sample of the general population.

Methods: A time-series analysis was used to test the association between daily air pollution and VTE hospitalizations in Santiago between 2001 and 2005. Results were adjusted for long-term trends, day of the week and average daily humidex.

Results: From a population of 5.4 million, there were, on average, 2.3 admissions for VTE per day. Pooled estimates of relative risk (RR) [95% confidence interval (CI)] of hospitalization for venous disease were: 1.07 (1.05, 1.09) for a 58.4 p.p.b. increase in ozone (O(3)); 1.06 (1.02, 1.09) for a 5.85 p.p.b. increase in sulphur dioxide (SO(2)); 1.08 (1.03, 1.12) for a 29.25 microg/m(3) increase in nitrogen dioxide (NO(2)); and 1.05 (1.03, 1.06) for a 20.02 microg/m(3) increase in particulate matter < or = 2.5 microm in mean aerodynamic diameter (PM(2.5)). For pulmonary embolism (PE) results were: 1.10 (1.07, 1.13) for O(3); 1.05 (1.02, 1.08) for SO(2); 1.07 (1.04, 1.09) for NO(2); and 1.05(1.03, 1.06) for PM(2.5), respectively.

Conclusion: Air pollution appears to be a risk factor for venous thrombosis and PE, a disease with a significant fatality rate.