Abstract
The rapid urbanization in Delhi has resulted in a tremendous increase in the number of motor vehicles with the increase in population and urban mobilization. The vehicular traffic is now recognized as one of the main sources of air pollution in Delhi and has noticeable impact on air quality. The emission of criteria pollutants namely Carbon Monoxide (CO), Nitrogen Oxide (NOx) and Particulate Matter (PM) due to vehicles is estimated through the International Vehicle Emission (IVE) model, which includes the different driving modes of vehicles and meteorological parameters. The estimated emissions of Carbon Monoxide (CO), Nitrogen Oxides (NOx) and Particulate Matter (PM) due to different types of vehicles in the year 2008–09 are found to be 509, 194 and 15 tons/day respectively. The diurnal variation of emissions of air pollutants shows two peaks, which are fortunately matching with the morning and evening office hours. The emissions of CO and NOx due to personal cars (PCs) are found to be about 34% and 50% respectively, and the emission of CO due to 2 W (2- Wheeler) is about 61%. Similarly, the Heavy Commercial Vehicles (HCVs) are contributing PM about 92%. The analysis of fuel-wise emission of pollutants reveals that CO is mainly contributed by petrol, and NOx and PM are contributed by diesel. It is also noticeable that CO, NOx and PM emissions at ITO, one of the busiest traffic intersections of Delhi, are approximately 15, 6 and 0.5 tons/day respectively, which are found to be the maximum followed by Kashmiri Gate (ISBT), Nizamuddin etc. The present vehicular emissions inventory has been compared quantitatively with previous studies of Delhi. The present vehicular emission inventory has also validated using US environmental protection agency’s (USEPA’s) AERMOD model with observed concentration at different locations in Delhi. However, the present study shows that the air quality of Delhi has been degraded due to high level emissions of criteria pollutants.
Highlights
Delhi is spread over an area of 1,484 km2 (573 sq mi), of which 783 km2 (302 sq mi) is designated rural and 700 km2 (270 sq mi) urban
The total emissions of Carbon Monoxide (CO), Nitrogen Oxide (NOx) and Particulate Matter (PM) from different types of vehicles over the study area of Delhi are found to be approximately 509, 194 and 15 tons/day respectively during the year 2008–09 and are shown in Table 1, which reveals that 2 wheelers (2W) and personal cars (PCs) are the mainly emitting the CO and NOx respectively, while heavy commercial vehicles (HCV) are mainly emitting PM
It is noticeable that the emissions of different criteria pollutants are varying differently into the different operating conditions of vehicles, e.g., CO emissions are found to be higher during idling and decelerating than cruising, the NOx and PM emissions are lower during idling and decelerating than cruising
Summary
Delhi is spread over an area of 1,484 km (573 sq mi), of which 783 km (302 sq mi) is designated rural and 700 km (270 sq mi) urban. The city's population is increasing rapidly with a consequent increase in the number of vehicles without a commensurate increase in road length. The number of vehicles registered in Delhi has already crossed 6 million and a sizeable vehicular traffic joins Delhi roads from the neighboring states (DSH 2010). The number of vehicles per kilometer of road in Delhi has gone up from 128 to 191 between 2003 and 2009. The vehicle population growth in Delhi is sharply increased by an average annual rate 7.40% for private vehicles and 9.15% for commercial vehicles causing severe transportation and environmental problems (GNCTD 2010). It has been found that irrespective of road classes, about 30% of time, vehicles travel below 20 km/h speed. Delhi is at the position of the world’s 5th worst city in traffic jam point of view (The Economic Times 2010).
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