Impact of the use of segregated streets in the elemental carbon concentrations in Santiago de Chile

Abstract

The high particle concentrations that are observed in Santiago de Chile during winter have prompted the government to pursue several approaches to reduce the contamination. One of these strategies was to change the traffic direction, and privileges in several streets. The main avenue (Alameda), which has 5 lanes each way, was segregated such that in three of them, only public buses can circulate and the other two lanes can be used by other vehicles. The objective is that the buses can circulate more freely, thus reducing emissions. During winter of 2001, we have measured the elemental carbon (EC) concentration along Alameda Avenue and several other streets with a light-absorption coefficient equipment built at the University of Santiago. The morning rush hour peak can be seen for all months indicating that the influence of traffic in this area is high. The EC concentration during rush hour represents an average of 25% of the total concentration. In addition, the average in EC concentration (for all months) due to rush hour traffic is higher in the street with no segregated traffic than the other two stations that have segregated traffic. However, the large variability in the data does not allow concluding with statistical significance that there is a reduction in EC pollution during rush hour. The average values of the elemental carbon concentration in 4 stations have been measured, and two of them show high values, the other two show lower values that depend on the location across the city. These results, allow drawing approximately the limits of an area with high elemental carbon concentration.