Exposure to elevated levels of ambient air pollutants can lead to adverse cardiovascular effects. Perturbation of the coagulation balance is one of the potential mechanisms. However, evidence regarding the impact of improvement in air pollution on blood coagulability in COPD patients has never been reported. Coagulation processes are known to be of relevance for cardiovascular pathology; therefore, this study aimed to investigate the association of short-term air pollution exposure with blood marker (D-dimer) of coagulation. A 3-year (through the Asian game) cohort study based on the GIRD COPD Biobank Project was conducted in 36 COPD patients to estimate whether changes in measurements of D-dimer were associated with changes in pollutant concentration, comparing for 51 intervention days (November 1-December 21) in 2010 with the same calendar date of baseline years (2009 and 2011). Daily mean concentrations of air pollutants and meteorological variables were measured during the time. Daily PM10 decreased from 65.86 μg/m(3) during the baseline period to 62.63 μg/m(3) during the Asian Games period; daily NO2 decreased from 51.33 to 42.63 μg/m(3). SO2 and other weather variables did not differ substantially. We did not observe statistically significant improvements in D-dimer levels by 9.86% from a pre-Asian game mean of 917 ng/ml to a during-Asian game mean of 1007 ng/ml, platelet number by 11.66%, PH by -0.15%, PCO2 by -6.54%, and PO2 by -1.16%. In the post-Asian game period, when pollutant concentrations increased, most outcomes approximated pre-Asian game levels, and similar effects were also demonstrated in D-dimer, platelet number, and arterial blood gas. For D-dimer and platelet number, we observed statistically significant increases associated with increases in NO2 at lag 1-3 and SO2 at lag 2-4. For PH, PCO2, and PO2, any significant effect was not demonstrated. This study gives no support to the hypothesis that reduction in air pollution levels during the 2010 Asian game is associated with activation of blood coagulation with COPD patients. However, one step forward has been made on the gap between improved air pollution and blood coagulability. Meanwhile, our study also provides evidence for the presence of a hypercoagulative state in systemic circulation in COPD patients. Additional studies employing other susceptible populations and endpoints are pending.
Keywords: Air pollution; Asian games; D-dimer; Intervention.