PM_2.5 Predictions in a Congested Urban Street Using CAL3QHC Model

The road traffic are major source of respirable suspended particulate matters, especially PM_2.5, i.e. particles having their aerodynamic diameter equivalent to or less than 2.5 micrometer. These particles impart in respiratory diseases and directly affect the lower region of respiratory system. In urban areas, invariably the roads are surrounded by high rise buildings which cause trapping of PM_2.5 in the lower region. Under this situation, the dispersion behavior of pollutant becomes complex and the location of the trapped pollutants should be known in order to improve ways to mitigate the health effects of PM_2.5 by providing proper ventilation. Therefore, present study focuses on the identification of critical location/locations by prediction of PM_2.5 concentration using CAL3QHC model. The relevant input parameters as traffic volume, weighted average emission factors, meteorological data and site conditions have been collected and used for models run. The PM_2.5 concentration has been predicted for parallel and perpendicular directions to the street as well as various receptor locations in the close proximity of urban street. The predicted results show that the maximum concentration (110.00 μg/m³) occurs at evening peak. The study concludes that the PM_2.5 concentration predicted has been observed to be much more than the prescribed value of PM_2.5 by USEPA.