Air quality assessment in tunnels: Field measurements and mathematical modeling

Traffic-induced emissions are a major source of urban air pollution. As a result of increased emissions and inadequate ventilation, the concentration of these pollutants in confined spaces such as tunnels can result in deleterious impacts on health and the well being of exposed population. The large difference in pollutant concentrations between the inside and outside of a tunnel has been used to derive on-road emission factors. This paper assesses vehicle-induced emissions and air quality inside a heavily traveled tunnel in an urban area. Accordingly, tunnel atmosphere has been sampled and characterized, mathematical modeling using simple mass balance and quasi steady-state mass balance models have been applied to derive emission factors, and simulate field measurements. Control measures are proposed based on field measurements and model simulation results.