Objective: Evidence on potential cardiovascular benefits of personal-level intervention among the elderly exposed to high levels of particulate matter (PM) remains limited. We aimed to assess improvements in surrogate markers of cardiovascular injury in vulnerable populations at risks by using indoor air filtration units. Methods: We conducted a randomized crossover trial for 2 separate 2-week air filtration interventions in 20 households of patients with stable chronic obstructive pulmonary disease and their partners in the winter of 2013, with concurrent measurements of indoor PM. The changes in biomarkers indicative of cardiac injury, atherosclerosis progression and systemic inflammation following intervention were evaluated using linear mixed-effect models. Results: In the analysis, average levels of indoor PM with aerodynamic diameters < 2.5 µm (PM_2.5) decreased significantly by 59.2% (from 59.6 to 24.3 µg/m³, P < 0.001) during the active air filtration. The reduction was accompanied by improvements in levels of high-sensitivity cardiac troponin I by −84.6% (95% confidence interval [CI]: −90.7 to −78.6), growth differentiation factor-15 by −48.1% (95% CI: −31.2 to −25.6), osteoprotegerin by −65.4% (95% CI: −56.5 to −18.7), interleukin-4 by −46.6% (95% CI: −62.3 to −31.0) and myeloperoxidase by −60.3% (95% CI: −83.7 to −3.0), respectively. Conclusion: Indoor air filtration intervention may provide potential cardiovascular benefits in vulnerable populations at risks.