Horizontal gradients of traffic related air pollutants near a major highway in Agra, India

In the present study, horizontal gradients of airborne particles and gases were observed perpendicular to the national highway (NH-2) in Agra, India. A negative association was found between distance (from the highway) and ambient concentrations of pollutants. Gradients suggest that the major impact of traffic flow on the pollutants concentration lies within 250 m distance. Over the total measured distance (0-500 m), the maximum percent decrease in concentrations was observed for total suspended particulate matter (TSPM), particulate matter with aerodynamic diameter less than 10 mu m (PM(10)), sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)) and carbon monoxide (CO) within 0-250 m distance range. However, no significant decrease in concentrations of carbon dioxide (CO(2)) was obtained. Correlations between all of the pollutants considered in this study are positive with many of them being highly correlated and significant, which shows that their sources are almost similar. On comparing the pollutants concentrations with available standards of Central Pollution Control Board (CPCB), SO(2), CO, NO(2) and O(3) concentrations were found within the permissible limits, whereas PM(10) concentration was found higher. This study generates data which can be useful for Asian city planners for planning residential colonies so as to cause minimum exposure to the residents.