Determination of the amount of benzene, toluene, ethylbenzene and xylene compounds (BTEX) in outdoor and indoor environment of schools in two regions of Isfahan in 2016

Among the volatile organic compounds, benzene, toluene, ethylbenzene and xylene compounds (BTEX) are important as air pollutants that have harmful effect for health even at very low concentrations. The main source of these compounds is the exhaust gases from vehicles exhaust. The purpose of this study was to measure BTEX compounds in outdoor and indoor environment of 4 high schools located in two districts of Isfahan and Chadegan city. Samples of air from inside and outside the schools were collected by individual sampling pumps using active carbon tubes. Then BTEX compounds were extracted by solvent CS2 and measured by mass spectrometric gas chromatography (GC-MS). Findings: The average concentration of BTEX compounds in Isfahan city was higher than Chadegan. Also, the concentration of BTEX compounds in Isfahan region 2 (Imam Hossein Square) was higher than Zone 1 (Chahar Bagh Khaju) and the highest and lowest concentrations among the BTEX components were respectively in relation to toluene and ethylbenzene. There was not significant difference between Indoor/Outdoor ratio in two regions. There was no significant relationship between the indoor and outdoor concentrations of BTEX compounds in two cities and two regions, which shows that the indoor environment is contaminated by internal resources. Based on the results, the city of Isfahan was more polluted then Chadegan. Also, region 2 in Isfahan was more polluted than region 1. So that the pollution is more related to external sources such as traffic. Keywords