Breathing in the margins: Rethinking indoor air pollution and housing equity in urban slums

Indoor air pollution (IAP) is a significant public health concern, especially in informal housing and urban slums within low- and middle-income countries (LMICs). This comprehensive review of recent research focuses on the sources, impacts, and responses related to poor indoor air quality (IAQ) in these environments. Common household activities such as cooking with solid fuels, indoor smoking, and inadequate ventilation are primary contributors to elevated levels of harmful pollutants. These pollutants include fine particulate matter (PM₂.₅), carbon monoxide (CO), nitrogen dioxide (NO₂), and volatile organic compounds (VOCs). Exposure to these pollutants is strongly associated with respiratory and cardiovascular diseases, with women and children being the most vulnerable due to their prolonged indoor presence. The review emphasizes that structural and socioeconomic factors—such as overcrowding, poor building design, and limited access to clean energy—exacerbate indoor air quality issues in low-income households. Although interventions like improved stoves, cleaner fuels, and natural ventilation have shown some success, their effectiveness is often limited by factors such as affordability, user behavior, and daily habits. A significant challenge remains the lack of comprehensive field-based data, which hampers the development of effective, evidence-based solutions. Additionally, indoor conditions such as dampness, mold growth, and culturally ingrained practices like incense burning and insecticide use are often overlooked but contribute substantially to poor air quality. These factors are frequently excluded from standard monitoring frameworks, reducing the accuracy and scope of current assessments. Regional differences across South Asia, Sub-Saharan Africa, and Latin America further demonstrate how climate, household infrastructure, energy access, and regulatory capacity influence indoor pollutant levels and the vulnerability of populations. This review advocates for more inclusive, locally tailored strategies that integrate housing design, public health initiatives, and community engagement to effectively reduce indoor air pollution and enhance living conditions in underserved urban areas.