# A Review of Indoor Air Quality in Social Housing Across Low- and Middle-Income Countries
## 4 Discussion  
The scoping review was based on IAQ interventions across several developing nations in social housing setting, focusing on particulate matter such as PM2.5 and PM10, alongside other pollutants including CO, CO2, SO2, formaldehyde, TVOCs, VOCs, and PAHs. These pollutants are particularly concerning because of their proven negative health impacts, especially in socio-economically disadvantaged areas [21, 74]. This review fills a critical gap in the existing IAQ literature that has predominantly centered on high-income nations by emphasizing the unique challenges of LMICs. To provide the comprehensive framework, the reviewed literature was categorized into the following five themes: Direct Measurements (DM), Health and Comfort (H&C), Retrofit and Maintenance (R&M), Comparative Studies (CS), and Housing Conditions and Socio-economic Fac-tors (HC&SeF). Strategic architectural modifications, such as optimizing building orientation, compactness ratio, and window geometry, can significantly improve IAQ through better ventilation [60, 61]. These strategies also reduce energy consumption and lower indoor temperatures, providing thermal comfort and affordable solutions for low-income households. In warm climates, interventions such as cross ventilation, stack effect, window size adjustments, increasing thermal mass, solar shading, and improved insulation have been simulated to improve natural ventilation [41, 53, 54]. Most of the included studies in this review focused on natural ventilation, particularly in warm and humid climates, where ventilation plays a crucial role in improving air exchange and thermal comfort [35, 45, 48]. However, a notable limitation within the reviewed literature is that the applicability of these interventions is often specific to the region. While natural ventilation strategies are effective in warm-humid climates, in colder regions it requires balancing ventilation with insulation and heating needs [76, 77]. The sizes and layouts of indoor spaces, particularly kitchens with volumes smaller than 15 m\({}^{3}\), have a significant negative impact on indoor pollutant levels [31, 41]. Recent studies [78, 79, 80] examined the importance of kitchen ventilation and direct IAQ monitoring in identifying high-risk environments. These perspectives are essential for creating interventions that are specific to the behavioral and spatial settings of social housing. Digital tools like building information modeling (BIM) and artificial intelligence (AI) enable practical interventions to improve IAQ [81]. For example, the dynamic hybrid air-permeable ceiling (DHAPC) system in Malaysian social housing, achieved a 98% reduction in particulate matter levels by using recycled glass insulation materials and activated-carbon filters [37]. BIM has been effectively used in social housing to identify ventilation inefficiencies, suboptimal window placements, and air leaks [11]. AI technologies also support these efforts by enabling real-time air-quality monitoring and management. For example, an AI system was developed by [PERSON] et al. [82] that uses data from air sensors to adjust ventilation systems, reducing pollutant exposure and improving air quality for residents. Combining real-world data collection with BIM offers practical solutions to address IAQ issues for low-income households [61] but the high costs and technical expertise required for these technologies could limit their accessibility. A clean-living environment reduces short-term morbidity by minimizing exposure to harmful pollutants and improving overall respiratory health [69]. However, this review shows that there is a noticeable health disparity related to poor IAQ, particularly respiratory issues, and mortality rates [83; 84; 85]. Poor IAQ in social housing can be attributed to insufficient infrastructure, like unreliable access to electricity, water, and heating, which forces occupants to rely on alternative sources, such as firewood, kerosene, paraffin, and gasoline, all of which decrease living standards [65; 86].