Assessment of vehicular pollution in Kolkata, India, using CALINE 4 model.

CALINE 4 offers several advantages over other models and is chosen as the base model for the purpose of developing a modified line source model for the city of Kolkata. Carbon monoxide is chosen for the model because it is principally emitted from vehicular sources. Average date wise background concentration is developed with the available data in different seasons. It is observed that, under actual conditions at Beleghata and Taratala, shift 1 (6am-2pm) is better correlated than shift 2 (2pm-10pm) without considering canyon option. Results show slightly better correlation coefficient and a lower standard deviation using the available season-wise 8-h average background concentrations rather than the generated average date-wise background concentrations. From the results, correction factors are developed for the city. Validated results near the HUDCO crossing show that CALINE 4, with the correction factors, can be applied reasonably well (mean error 0.37) for the prediction of carbon monoxide (CO) of Kolkata. CALINE 4 predictions with correction factors have revealed that construction of a flyover connecting VIP Road to EM bypass will lead to lessening of CO. The CALINE 4 model with the suitable correction factors should serve as a guide for proper air quality management.