Table 4 shows the mean VOC concentration ratios of the microenvironment to RAMA. It confirms that the micro-environmental toluene concentration is three to approximately nine times higher as compared to mean benzene. When compared, ratios of mp-xylene to o-xylene, the latter shows two to three times higher concentrations. At the hospital, there were higher concentrations of the compounds under study. This can be attributed to the utilisation of different antiseptics and disinfectants inside the buildings. A remarkably high concentration of toluene was found at the bus station. Lower values for benzene/VOCs were found at the hospital and the Tlalnepantla and Merced stations.