Spatial–Temporal Assessment of Indoor Air Quality and Occupational Risk-Control Practices in an Oil and Gas Facility in Delta State, Nigeria

This study evaluated the space- and time-varying Indoor Air Quality (IAQ) and Occupational Risk control Practices (ORCP) in Administrative Workspaces (AW) of an operating Oil and Gas Facility (OGF) in Delta State, Nigeria. A workplace-based observational cross-sectional design was used, with morning and evening measurements conducted in the reception area and three administrative offices, yielding 8 workspace-period observations. PM₂.₅, PM₁₀, CO₂, CO, SO₂, NO₂, TVOC, and relative humidity and temperature were measured using calibrated direct reading instruments. Composite pollution-burden scoring as well as descriptive statistics, exact Wilcoxon signed-rank tests, paired PERMANOVA, correlation analysis, hierarchical clustering, sensitivity analysis and chi-square goodness-of-fit tests were used to analyse the data. The mean value of PM₂.₅, CO₂, SO₂, NO₂ and TVOCs were the highest for the Reception as the major hotspot, while for Administrative Office 2, the mean value of PM₁₀ was the highest. Evening concentrations increased by the evening concentrations increased by 18.37% for PM₂.₅, 11.15% for PM₁₀ and 77.78% for CO, with perfect positive rank-biserial effects indicating consistent evening deterioration. The amount of variation in multivariate pollution profiles accounted for by workspace was 77.7%, compared with 13.8% accounted for by the monitoring period. The order of the composite burden score remained unchanged across leave-one-pollutant-out sensitivity analyses, with the highest score observed in Reception–Evening (1.515). Administrative controls varied greatly, χ²(6)=41.18, p<0.001, (w=0.531), and are highlighted by a lack of signage, supervision and intensive safety checks. Significant mixed-pollutant exposure hotspots are also found in administrative areas, the study concludes. Improving ventilation, isolating sources, using filtration, conducting routine monitoring across different seasons, enhancing engineering controls, and verifying SO₂ and NO₂ units before the regulation is interpreted are all priority actions.