Enhancing indoor air quality: Harnessing architectural elements, natural ventilation and passive design strategies for effective pollution reduction — A comprehensive review

Air pollution poses a critical global challenge with severe environmental and human health implications. The associated health risks, including premature mortality, underscore the urgency of effective mitigation strategies. Many studies focus on control strategies without considering specific contaminant types, and there is a notable gap in research on cost-effective, eco-friendly methods, especially in countries facing substantial air pollution challenges. This study aims to fill this gap by providing a comprehensive review of various air pollutants and proposing optimal passive design strategies for mitigating them in building facades. Through a structural process and comparative analysis of existing literature, this study evaluates the cost, maintenance, applicability of retrofitting, and removal efficacy of three categories of control strategies: bio-filtration, adsorbents, and water-based approaches. The results confirm that biological air purification systems are more effective than other methods at reducing PM 2.5, PM 10, and VOCs. Moreover, the cost analysis confirms that the more costly approaches are photocatalytic filters and metal-organic frameworks derived from the adsorbent solutions. Thus, the study suggests applying cost-effective techniques like facade biofiltration, and water-based curtain façade in areas with high air pollution. In terms of the applicability of retrofitting, the results ascertain adsorbent strategies are the most effective for reducing air pollutants in existing buildings followed by water-based methods. Considering limitations associated with certain strategies, such as the high cost and regular maintenance, this study proposes five integrated strategies for the effective control and removal of pollutants from building exteriors. By addressing these gaps in knowledge and offering practical insights, this research contributes valuable guidance for architects, policymakers, and practitioners in developing sustainable, efficient solutions to combat indoor air pollution effectively.