Health Risk Assessment Associated with Diesel Induced SO₂ Emissions in Erbil City: A Box Model Estimation.

Abstract

Diesel with high sulfur content is a major contributor to sulfur dioxide (SO₂) emissions in urban environments, posing health risks to populations residing near high-traffic roads. This study investigated the influence of diesel sulfur content on SO₂ exposure and the associated non-carcinogenic health risks in residential areas of Erbil city. Sulfur levels in 65 diesel samples were measured and incorporated into a box model to estimate ambient SO₂ concentrations, which were used to evaluate exposure through the Hazard Quotient (HQ) across different demographics, including infants, toddlers, children, adults, and pregnant women. The assessment considered three ventilation scenarios: adequate, moderate and poor indoor ventilation. Results revealed a strong positive relationship between sulfur content and SO₂ concentration, resulting in progressively higher HQ values across all demographics. Under adequate ventilation HQ remained below the safety threshold (HQ < 1), regardless of the sulfur level. In contrast, moderate and poor ventilation resulted in HQ greater than unity, particularly for infants, toddlers and children, with a maximum HQ of 10.3. However, HQ values for adults and pregnant individuals exceeded unity only under poor ventilation. Diesels complying with Worldwide Fuel Charter (WWFC) standards (≤500 ppm sulfur) resulted in negligible health risks under all modeled conditions, whereas locally produced fuels meeting current Kurdistan Region Government (KRG) standards produced significantly higher risk under limited ventilation. Based on the worst-case scenario, the health-protective sulfur level was estimated to be 1600 ppm. These findings highlight the necessity of diesel hydrodesulfurization, stricter sulfur regulations and adequate ventilation to minimize SO2 exposure.