The influence of vehicle age and traffic congestion on air pollution in Ulaanbaatar: A study of NO_x and PM emissions

抄録

Mongolia's rapidly growing vehicle fleet, especially in Ulaanbaatar, is a major contributor to urban air pollution, with nitrogen oxides (NO_x) and particulate matter (PM) being the primary pollutants. This study investigates the impact of vehicle age and traffic conditions on emissions under both heavy and normal traffic scenarios. Real-world emissions were measured across petrol, diesel, and hybrid vehicles. The results reveal that older vehicles produce significantly higher levels of NO_x and PM due to outdated engine technologies and insufficient emission controls. Traffic congestion further exacerbates emissions, particularly at low speeds (under 10 km/h), where frequent idling and stop-and-go movement reduce engine efficiency. Among vehicle types, diesel and hybrid vehicles emitted more NO_x compared to petrol and gas-powered ones under congested conditions. These findings highlight the urgent need for policies addressing vehicle age limits, traffic flow improvement, and the adoption of cleaner vehicle technologies to enhance air quality in Ulaanbaatar.