Alterations by air pollution in inflammation and metals in pleural effusion of pneumonia patients

Air pollution is known to increase the risk of pneumonia. However, the effects of air pollution on the pleural effusion of patients with pneumonia are unclear. The objective of this study was to investigate alterations in inflammatory–immune biomarkers by air pollution in patients with pneumonia by analyzing their pleural effusion. Patients who had undergone thoracentesis to drain their pleural effusion in a hospital were recruited for this study. Patients with pneumonia and those with congestive heart failure respectively served as the case and control groups. We observed that an increase of 1 ppb in one-year NO₂ was associated with a decrease of 0.105 ng/mL in cluster of differentiation 62 (CD62) (95% confidence interval (CI) = -0.085, -0.004, p < 0.05) in the pleural effusion. Furthermore, we observed that an increase in one-year 1 ppb of NO₂ was associated with a decrease of 0.026 ng/mL in molybdenum (Mo) (95% CI = -0.138, -0.020, p < 0.05). An increase in one-year 1 ppb of SO₂ was associated with a decrease of 0.531 ng/mL in zinc (95% CI = -0.164, -0.006, p < 0.05). Also, an increase in one-year 1 ppb of O₃ was associated with a decrease of 0.025 ng/mL in Mo (95% CI = -0.372, -0.053, p < 0.05). In conclusion, air pollution exposure, especially gaseous pollution, may be associated with the regulation of immune responses and changes in metal levels in the pleural effusion of pneumonia patients.