Carbon Monoxide Pollution Levels at Environmentally Different Sites

Environmental characteristics such as topography, altitude, anthropogenic activity such as traffic, industrial gaseous effluents, proximity to all sources of pollution etc., have considerable influence on the abundance, residence time and retention of tropical trace gases over a locale. When the trace gas is toxic with its source at the surface of the Earth and has residence time of the order of several days, like in the case of carbon monoxide (CO), this trace gas becomes a criteria pollutant. Under the ISRO Geosphere Biosphere Programme (ISRO-GBP), a scientific study was initiated with a view to studying CO baseline at a tropical coastal station (Thiruvananthapuram) and to compare short-term CO measurements carried out in different environments such as a metropolis, a mining site and a pristine midland environment. CO is an air pollutant and is being monitored at a tropical coastal station Thiruvananthapuram since 2003 using an infrared analyzer. Also, for short durations CO was measured at three other environmentally different sites viz., Palode (near Thiruvananthapuram, a midland hill station with dense vegetation at an altitude of 140m ASL on Western Ghats), New Delhi (metropolitan city) and at Jaduguda (a mining site in Jharkhand state) near Kolkatta. From these measurements, the behaviour of CO at different environments was studied. Ambient CO at these sites, their diurnal patterns and the effect of vehicular emission inferred from weekday-weekend behaviour was delineated. This study revealed that Palode has the lowest ambient CO, followed by Thiruvananthapuram, Jaduguda and then New Delhi. Modulation of ambient CO by the vehicular emissions was observed at New Delhi, Thiruvananthapuram and Palode, but was absent at Jaduguda. The results of the characteristic CO levels encountered at different environmental locations, the response to traffic, the main anthropogenic activity that affects CO levels, are presented in detail and discussed in the manuscript