Residential VOCs concentration levels in Nsukka, Nigeria

Abstract

The concentrations of 26 VOCs were measured in ten rural and ten urban households for two 7-day sampling campaigns in the Nsukka area, Southeast Nigeria, between 2017 and 2019. Samples were passively collected in the kitchen, living room, and outdoor using Tenax TA axial sorbent tubes. Analysis was done by thermal desorption gas chromatography coupled with mass spectrometry using ethylbenzene-d10 as an internal standard. The wet season kitchen and outdoor TVOCs are 265 and 45 μg/m3 in urban, and 199 and 21 μg/m3 in rural households. The dry season median TVOCs concentrations in the kitchens, living rooms, and outdoors are 254, 115, and 71 μg/m3 in urban and 324, 145, and 41 μg/m3 in rural areas, indicating a rank order of kitchen > living room > outdoor. This indicates spatial and seasonal variability of the VOCs concentration among the locations in the homes and between urban and rural areas. However, the difference between the urban and rural TVOCs levels is only significant (p < 0.05) for the outdoor levels.The TVOCs indoor to outdoor concentration ratios for the kitchen during the dry season are 1.3–18, implying indoor sources. The median (range) benzene concentrations in the kitchens are 80 μg/m3 (10–306 μg/m3), 47 μg/m3 (18–90 μg/m3), 26 μg/m3 (4–122 μg/m3), and 15 μg/m3 (8–104 μg/m3) for kitchens using firewood, charcoal, kerosene, and LPG which indicates that exposure to benzene could be five times more in firewood kitchens than in LPG ones. Furthermore, the estimated lifetime cancer risk and hazard quotient from the present study exceed the respective thresholds of 6.00E-06 and 1.0, indicating that people are at risk in the studied homes and underscores the urgency for effective air quality management in the area.