Environmental Impact Assessment of Indoor Air Quality in Selected Residential Areas in Port Harcourt Metropolis

PM2.5 PM10 HCHO VOC Meciarova et al. (2017) - - - 330.2g/m3 for family houses and 519.7g/m3 for apartment Zhou et al. (2015) 92.2mg/m3 118.6mg/m3 - - Chen et al. (2014) 0.813mg/m3 - 0.142mg/m3 0.218mg/m3 Yu et al. (2017) - - 0.02mg/m3 0.45mg/m3 Patrick et al. (2018) - - - 0.048mg/m3 Akpofure (2015) 89-112g/m3 255-391 g/m3 - - Abulade et al. (2008) 006-020g/m3 006-022 g/m3 0.001- 0.030mg/m3 0.003- 362mg/m3 Ideriah et al. (2020) 0.13mg/m3 0.37mg/m3 - - Bennett et al. (2018) 8.9g/m3 30.1g/m3 - - Our results 47.90 – 59.60 g/m3 54.80 – 68.40g/m3 - - Table 3.3: Socio-Demographic Characteristics and Household Attributes of Respondents (n = 249) Variable Category Frequency Percentage (%) Sex Male 107 43 Female 142 57 Total 249 100 Marital Status Single 122 49 25 25.5 26 26.5 27 27.5 28 28.5 29 Level Sampling Station Temperature (°C) , Married 108 43.4 Others 19 7.6 Total 249 100 Age 21–30 63 25.3 31–40 102 41 41–50 53 21.3 51–60 21 8.4 Above 60 10 4 Total 249 100 Occupation Student 94 37.8 Company worker 27 10.8 Civil servant 91 36.5 Trader 37 14.9 Total 249 100 Academic Level No formal education 17 6.8 Primary/Secondary 130 52.2 Diploma/Degree 63 25.3 Postgraduate 39 15.7 Total 249 100 Religion Christianity 143 57.4 Islam 76 30.5 African Traditional Religion 12 4.8 Others 18 7.2 Total 249 100 House Type One-bedroom flat 97 39 Two-bedroom flat 92 36.9 Three-bedroom flat 49 19.7 , Duplex 11 4.4 Total 249 100 Floor Type Concrete 29 11.6 Tiles 123 49.4 Rug 46 18.5 Carpet 51 20.5 Total 249 100 Kitchen Position Inside building 136 54.6 Outside building 102 41 Corridor 11 4.4 Total 249 100 Cooking Appliances Electric cooker 20 8 Gas cooker 100 40.2 Kerosene stove 86 34.5 Firewood/Others 43 17.3 Total 249 100 Activities Affecting Air Quality Smoke indoors 26 10.4 Smoke outdoors 21 8.4 Use mosquito coil 49 19.7 Use insecticides 83 33.3 Use perfumes/sprays 70 28.1 Total 249 100 Power Generator Use Always 87 34.9 Sometimes 114 45.8 Not at all 48 19.3 Total 249 100 , Generator Location Inside house 60 24.1 Outside house 121 48.6 Separate house 68 27.3 Total 249 100 Ventilation Condition Well ventilated 122 49 Poorly ventilated 65 26.1 Temperature too high 51 20.5 Temperature too low 11 4.4 Total 249 100 Average Occupancy 2 persons 8 3.2 3 persons 129 51.8 4 persons 43 17.3 Above 4 persons 69 27.7 Total 249 100 Detergent/Disinfectant Use All the time 97 39 Sometimes 123 49.4 Never 29 11.6 Total 249 100 Quantity of Detergent 1 teaspoon 51 20.5 2 teaspoons 117 47 3 teaspoons 49 19.7 Above 3 teaspoons 32 12.9 Total 249 100 Quantity of Disinfectant 1 ml 80 32.1 2 ml 112 45 3 ml 30 12 Above 3 ml 27 10.8 Total 249 100 , Reported Symptoms Heavy-headed 28 11.2 Headache 50 20.1 Runny/stuffy nose 26 10.4 Dry/sore throat 64 25.7 Cough 31 12.4 None 50 20.1 Total 249 100 4. Discussion 4.1 Particulate Matter (PM10 and PM2.5) Concentrations The results presented in Table 3.1 indicate that indoor particulate matter concentrations across the selected residential locations in Port Harcourt Metropolis are relatively elevated. The mean PM10 concentrations ranged from 54.8 μg/m3 (Elekahia Housing Estate) to 68.4 μg/m3 (Mile Three), while PM2.5 ranged from 47.9 μg/m3 to 59.6 μg/m3 across the study area. These values significantly exceed the World Health Organization 2021 air quality guideline of 15 μg/m3 (24-hour mean) for PM2.5 and 45 μg/m3 for PM10, suggesting that residents are exposed to unhealthy indoor air conditions. Elevated PM levels in indoor environments have been widely linked to increased risks of respiratory and cardiovascular diseases (WHO, 2021; Zhang et al., 2022). Spatial variations observed among locations may be attributed to differences in traffic density, proximity to major roads, building design, and household activities. For instance, Mile Three and Aggrey Road, which recorded the highest concentrations, are characterized by intense commercial activities and heavy vehicular movement. This supports findings by Eze et al. (2023), who reported that urban residential areas with high traffic flow tend to exhibit increased indoor particulate levels due to infiltration of outdoor pollutants. Similarly, lower concentrations observed in Elekahia Housing Estate and Ogbogoro may be associated with relatively lower traffic intensity and better residential planning. However, even these “lower” values remain above recommended thresholds, indicating that indoor pollution is a widespread issue across the metropolis. 4.2 Influence of Indoor Microclimatic Conditions The recorded indoor temperature ranged from 26.4°C to 28.4°C, while relative humidity varied between 55.9% and 66.1%. These relatively narrow ranges suggest that meteorological conditions were fairly stable across locations, implying that variations in pollutant levels are more strongly influenced by anthropogenic factors rather than environmental variability. However, the relatively high humidity levels (above 60% in some locations) are noteworthy. According to Azuma et al. (2020), elevated indoor humidity can enhance the formation and persistence of secondary pollutants, including biological contaminants such as mold spores and bacteria. This may indirectly worsen indoor air quality and amplify health risks. Temperature also plays a role in pollutant behavior. Higher indoor temperatures can increase the emission rates of volatile compounds from household materials and products (Li et al., 2021). , Although VOCs were not extensively reported in this dataset, the observed temperature range suggests conditions that could facilitate pollutant accumulation indoors. 4.3 Air Pressure and Indoor Air Dynamics Air pressure values across the study locations showed minimal variation, ranging from 25.9 to 28.9 (AP level). While air pressure is not a direct pollutant, it influences air movement, ventilation efficiency, and pollutant dispersion within indoor spaces. Stable air pressure conditions, as observed in this study, may indicate limited natural air exchange in certain buildings, especially where ventilation is poor. According to Wargocki and Wyon (2021), inadequate ventilation significantly contributes to the accumulation of indoor pollutants, particularly in urban residential environments. 4.4 Environmental and Public Health Implications From an environmental impact assessment perspective, the elevated levels of particulate matter observed in this study indicate a significant environmental health burden on residents of Port Harcourt Metropolis. PM2.5, in particular, poses serious health risks due to its ability to penetrate deep into the lungs and enter the bloodstream. Recent global studies have shown that long-term exposure to elevated PM2.5 levels is associated with increased incidence of asthma, chronic obstructive pulmonary disease , cardiovascular diseases, and premature mortality (Burnett et al., 2018; HEI, 2020). The results also suggest that indoor air pollution in the study area is largely driven by human activities, including: i. Use of generators ii. Cooking with kerosene and biomass fuels iii. Use of household chemicals iv. Poor ventilation practices These findings align with studies in similar urban environments in sub-Saharan Africa, where indoor pollution is strongly linked to energy poverty and urbanization challenges (Amegah & Jaakkola, 2019; Eze et al., 2023). 4.5 Overall Environmental Impact Assessment Sources: Household fuel combustion, generator emissions, traffic infiltration Pathways: Indoor accumulation, inadequate ventilation, building design Receptors: Residents (especially vulnerable groups such as children and the elderly) The study demonstrates that indoor air pollution constitutes a chronic environmental stressor in the study area. The persistence of pollutant levels above recommended standards indicates potential long-term impacts on both human health and environmental quality. 4.6 Comparison of Indoor Air Pollutant Levels with Previous Studies The particulate matter concentrations obtained in this study (PM2.5: 47.90–59.60 μg/m3; PM10: 54.80–68.40 μg/m3) fall within a moderate range when compared with previous studies, indicating persistent but not extreme indoor air pollution in the study area. For example, Akpofure (2015) reported higher particulate levels (PM2.5: 89–112 μg/m3; PM10: 255–391 μg/m3), suggesting more severe exposure conditions in some urban environments, while Bennett et al. (2018) documented much lower values (PM2.5: 8.9 μg/m3; PM10: 30.1 μg/m3), reflecting cleaner indoor settings. These variations highlight the influence of household energy use, ventilation conditions, and urban , density on particulate concentrations. In comparison, gaseous pollutants such as formaldehyde and VOCs reported in Chen et al. (2014) (0.142 mg/m3 and 0.218 mg/m3 respectively) show that chemical pollutants can also significantly contribute to indoor air quality deterioration, although such parameters were not measured in the present study. Overall, the comparison suggests that while the current study area does not exhibit the highest recorded pollutant levels globally, the particulate matter concentrations remain above recommended health-based guidelines, indicating potential long-term exposure risks. The absence of HCHO and VOC measurements in the present study limits full comparison; however, existing literature consistently shows that indoor pollution is strongly driven by combustion activities, household chemicals, and inadequate ventilation. 4.7 Socio-Demographic and Household Characteristics of Respondents The socio-demographic characteristics reveal a predominantly youthful and economically active population, with the highest proportion of respondents aged 31–40 years (41%) and a slightly higher number of females (57%). Educational attainment is generally moderate, as over half of the respondents (52.2%) have only primary or secondary education, which may influence awareness of indoor environmental risks. Occupational distribution shows that students (37.8%) and civil servants (36.5%) form the majority of participants, reflecting a mixed urban residential setting. Household and environmental conditions indicate several potential contributors to indoor air pollution. Most respondents live in small apartments (one- and two-bedroom flats), with a high prevalence of indoor kitchens (54.6%) and frequent use of gas (40.2%) and kerosene (34.5%) for cooking. Generator usage is also widespread, with more than 80% of respondents using them at least occasionally, often located near living spaces. Although 49% of households report good ventilation, a considerable proportion experience poor airflow or thermal discomfort. Reported symptoms such as dry throat (25.7%), headache (20.1%), and cough further suggest possible exposure to indoor pollutants from combustion sources and household chemical use. 5. Conclusion This study assessed the environmental impact of indoor air quality in selected residential areas of Port Harcourt Metropolis using measurements of particulate matter (PM2.5 and PM10), meteorological parameters, and household survey data. The findings revealed that indoor PM2.5 and PM10 concentrations ranged from moderate to elevated levels across all sampled locations, with higher values generally observed in densely populated and traffic-influenced areas such as Mile Three, Aggrey Road, and Rumuola. Although the recorded concentrations were lower than some previously reported extreme urban values, they still exceeded desirable clean-air conditions, indicating a persistent exposure risk to residents. The study further established that indoor air quality is strongly influenced by household and behavioral factors, including the use of kerosene and gas for cooking, frequent generator usage, indoor kitchen placement, use of chemical-based household products, and varying ventilation conditions. These factors collectively contribute to the accumulation of indoor pollutants and microclimatic variations observed across the study locations. The reported prevalence of symptoms such as dry throat, headaches, and cough among respondents suggests possible associations between indoor environmental conditions and adverse health outcomes. In conclusion, indoor air quality in the study area presents a significant but often overlooked environmental health concern. While not uniformly severe across all locations, the levels of exposure identified indicate potential long-term health implications if no mitigation measures are , implemented. Therefore, improving ventilation systems, promoting cleaner energy sources, regulating generator emissions, and raising public awareness on indoor pollution sources are essential steps toward reducing exposure and enhancing residential environmental quality in Port Harcourt Metropolis.