Concentration, sources and toxic potential exposure of formaldehyde and BTEX in residential areas at XiCheng district, Beijing

Ambient levels of formaldehyde and BTEX (benzene, toluene and xylene) compounds were monitored at seven residential areas in Xicheng District, Beijing, during the period of November-December 2009. Formaldehyde was collected using 2, 4 dinitmphenyihydmzine (DNPH) modified silica tube and analyzed by HPLC. BTEX compounds were collected with activated carbon tube and analyzed by GC-FID. The concentrations of formaldehyde, benzene, toluene and xylene were in the rage of 3.0-736.0 μg m^-3, 3.0-174.1 μg m^-3, 2.0-2372.1 μg m^-3 and 1.0-879.0 μg m^-3, respectively. At the seven residential sites, the average concentrations of formaldehyde, benzene, toluene and xylene were 20.9 μg m^-3, 10.7 μg m^-3, 34.0 μg m^-3 and 15.3 μg m^-3. Carcinogenic potential compounds of benzene and toluene level exceeds the limit of BTEX set by European (10μg m^-3 for benzene, 25μg m^-3 for toluene). The statistical results showed the main sources of formaldehyde and BTEX in this investigation were organic adhesives and ligneous furniture. The human exposure levels of formaldehyde and acetaldehyde were also discussed. Compared to other sites of China, the exposure risks of low molecular carbonyl compounds in Beijing were higher.