Preliminary hazard assessment of air pollution levels in Nizwa, Rusayl and Sur in Oman

The World Health Organization (WHO) recognises air pollution as a serious public health concern in many developing countries due to the influx of energy-intensive industries with limited planning and exposure mitigation strategies. Due to industrial expansion and release of associated air pollutants in Oman, the US Environmental Protection Agency human health risk assessment (HHRA) model was used to determine the non-carcinogenic hazard associated with exposure to industrial emissions. Across the three industrial cities (Nizwa, Sur and Rusayl), the study found ambient average concentrations (μg/m³) of 1 h carbon monoxide (CO) (606–1974), nitrogen dioxide (NO₂) (7.7–43.9) and sulfur dioxide (SO₂) (4.8–9.0) and 24 h PM_2.5 (7.3–7.8) and PM₁₀ (38.7–51.5) to be significantly lower than both the Ministry of Environment and Climatic Affairs (MECA) and WHO limits. The HHRA analysis showed that exposure to the air pollutants produced low non-carcinogenic adverse health effects, as the hazard quotient (HQ) was found to be <1 among the population. However, there was an increase in HQ for WHO reference exposure level (REL) values compared with that of MECA; this is due to the relaxed/high REL limits of the latter. Future epidemiological studies involving long-term air pollution exposure assessment and health data may improve the reliability of the current HHRA estimates.