The population of megalopolis cities, motor vehicles, motor fuel consumption, and air pollution all have increased (Walsh, 1993, Chapter 1). World motor vehicle population growth reached 700 million in the year 2000. The air quality crisis in cities is often attributers in large measure (40–80%) to vehicular emissions. Urban India depicts a picture of metamorphosis. Most cities are growing rapidly. Moreover, urban populations are growing at a faster rate than the national average (Ghose, 2002). The feudal towns have changed to industrial cities, cities into metropolis and metros into megalopolis. Existing cities are expanding, new cities are being created, and adjacent cities are merging. This rapid growth of the urban population also brings with it increasing demands for energy-based goods and services. Owing to the expanding economic base, there is an influx of population migrating from the rural areas and urban fringe to the core city in search of better quality of life. The influx of population to the existing cities stresses the overstretched infrastructure of the urban areas, which is unable to cater to the ever-growing needs of in-migrants. Transportation systems are expanding everywhere. The improved performance of technology is presently insufficient to counteract growth. Projections, therefore, consistently show worsening air quality in the cities of India in future. This congruence has contributed to urban air pollution problem directly related to motor vehicle emissions of CO, O3, toxics and particulates (Davis, 1998). Because of sources of these emissions the public health implications (Utell et al., 1998; Anon, 1997) are substantial. An improved understanding of the association of the particulates with mortality suggests the importance of sub-micron particles (PM10) to which motor vehicles are major contributors (Anon, 1995). Automobile exhausts and certain industrial pollutants contain NO2,which by photochemical reaction produces O3and effects allergic asthmatics by augmenting allergic responses (Steinberg et al., 1991). Similarly SO2, NO, particulate matter and acid aerosols effect pulmonary function and cause inflammation of bronchial mucous (Karen and Michak, 1991; Giuseppe and Francesco, 1993). It has been observed from several studies that air pollution plays an important role in the genesis and augmentation of allergic disorder and it is described as a disease of civilized society (Dennis, 1996; Bonai et al., 1994). To evaluate such impacts, a fact-finding survey has been conducted to evaluate the status of urban air pollution at traffic intersections and its vulnerability index (VI) for an Indian megacity. The purpose of this paper is to highlight the severity of these issues and the immensity of the challenge of solving the problems in one of the worst polluted cities in the world Kolkata, the capital of West Bengal State is considered to be one of the most polluted megacities. A “no care” attitude, rapid and unplanned urbanization, continued growth of the metropolis (Mukherjee and Mukherjee, 1998a), uncontrolled vehicular density on insufficient badly cared road space, lack of adequate parking facilities (Kazimuddin and Banerjee, 2000), low turnover of old vehicles with too frequent breakdowns, undisciplined drivers, indifferent pedestrians together with a bad traffic management have taken the problems into threatening stage (Mukherjee et al., 1982). The use of leaded petrol fuel is higher in Kolkata than any other city (Neelman, 1993). Widespread malnutrition, poor hygiene sense and indifferent attitude among the population exacerbate and complicate the impact on human Fig. 1. Locations of air monitoring stations in the study area. health due to multiple environmental risks (Mukherjee and Mukherjee, 1998b).

The North portion of Kolkata, which is bounded by the River Hooghly and Barrakpore Trunk (B.T.) Road starting from Shyambazar to Rathtala, was selected for the study (Fig. 1). The area is mainly residential surrounded by a cluster of industries. Two thermal power plants, a number of small-scale industries especially gold smelting industries, a burning ghat exist in the area. The area is always overcrowded with loaded trucks, as the Vivekanada Bridge is one of the entry points to Kolkata. In addition, the study area is famous for the existence of a temple at Dakshineswar, which thousands of visitors, pilgrims from India and abroad visit every day.