Spatial and temporal variation of outdoor and indoor exposure of volatile organic compounds in Greater Cairo

Monthly measurements of volatile organic compounds (VOCs) were carried out in a field study in Greater Cairo in the period of 2005-2007. Ten apartments were chosen as sites for passive sampling of VOCs in different parts of Greater Cairo, Egypt taking into consideration the traffic volume profile across the city and the suburbs. The concentrations of 29 VOCs, belonging to the groups of alkanes, cycloalkanes, aromatic hydrocarbons, halogenated hydrocarbons and terpenes were measured indoor and outdoor at the same time. A strong correlation was found between sites with high traffic volume and the concentration of aromatic compounds. The measured VOC burden in the outdoor environment of the whole city is dominated by compounds related to vehicle emissions, e.g. the BTEX compounds (benzene, toluene, ethyl benzene and xylene). The spatial variation of the indoor BTEX exposure is similar to the outdoor exposure. This implies a strong infiltration of outdoor ambient air pollution into the indoor environment. The highest indoor BTEX concentration was measured in the city centre (172 μg/m3). Significant seasonal cycles with high values in winter and lower values in summer months could be modelled for indoor concentrations of BTEX and terpenes. This is in accordance with findings in Middle Europe (Germany) with completely different climate and building characteristics. © Author(s) 2010.