An Exploratory Comparison Of Indoor Air Quality In Retrofitted Dwellings In Abuja, Nigeria

Abstract

Indoor air quality (IAQ) in retrofitted residential buildings reflects the combined influence of ventilation conditions, building envelope characteristics, material emissions, occupant activities, and outdoor pollutant ingress. This is especially relevant in Nigeria, where empirical IAQ research remains limited relative to the scale of exposure risk, and where housing conditions, fuel use, and ventilation practices vary substantially across residential settings. This study adopted an exploratory cross-sectional, post-retrofit field design to assess IAQ in three purposively selected retrofitted dwellings across distinct urban districts in Abuja (Gwarinpa, Lokogoma, and Wuse II), comprising six monitored rooms (main living room and principal bedroom). The monitored dwellings had elapsed post-renovation periods of two years (D1, retrofitted 2024) and one year (D2 and D3, retrofitted 2025). Physical parameters including carbon dioxide (COâ‚‚), total volatile organic compounds (TVOC), particulate matter (PMâ‚‚.â‚… and PMâ‚â‚€), temperature, and relative humidity were continuously monitored for 48 hours per room during the 2026 dry season (1 February to 30 April; 288 cumulative hours) using calibrated continuous loggers (GrayWolf IQ-610 and TSI SidePak AM520). Data were analyzed using descriptive statistics, temporal profiling, cross-case comparison, and exploratory principal component analysis. Across all dwellings, bedrooms exhibited higher pollutant accumulation than living rooms, averaging 1024.3 ppm COâ‚‚ (vs. 763.7 ppm), 240 ppb TVOC (vs. 171 ppb), and 27.9 µg/m³ PMâ‚‚.â‚… (vs. 23.8 µg/m³). Dwelling D2 (retrofitted in 2025 with gloss paints and PVC finishes) exhibited the greatest internal burden, peaking in the bedroom at 1187 ppm COâ‚‚ and 318 ppb TVOC under single-sided, compartmentalized airflow. Conversely, Dwelling D3 demonstrated low indoor COâ‚‚ (living room: 688 ppm) under full cross-ventilation but recorded the highest particle concentrations (bedroom PMâ‚‚.â‚…: 29.7 µg/m³; PMâ‚â‚€: 64.8 µg/m³) due to untreated roadside particle ingress. Because envelope features, domestic routines, and external exposures varied simultaneously without pre-retrofit measurements, these findings cannot isolate determinant effects or establish the causal impact of retrofitting itself. The study instead provides preliminary, case-specific case evidence demonstrating that post-retrofit IAQ in tropical urban settings requires balancing natural ventilation provision with external particle filtration and low-emission material procurement, offering an empirical basis for larger longitudinal studies on retrofit-related indoor environmental performance in Nigeria.