Evaluation of a new passive sampler using hydrophobic zeolites as adsorbents for exposure measurement of indoor BTX

Abstract

Rapid urbanization in China has resulted in more serious pollution of indoor benzene, toluene, and xylenes (BTX), which can cause chronic adverse health effects on human beings. Passive sampling has been used to assess long-term BTX exposure. However, there is a lack of low-cost passive samplers suitable for large-scale sampling in China, which has limited the proper risk assessment of indoor BTX to the Chinese. In this study, a cost-effective radial diffusive sampler (THPDS, Tsinghua Passive Diffusive Sampler) with hydrophobic silica zeolites as adsorbents is developed. The performance of THPDS was evaluated, including blank values, method detection limits (MDLs), desorption efficiency etc. The sampling rates (SRs) were measured under various experimental conditions provided by an exposure chamber. Results indicate that the sampling rates of THPDS keep relatively constant with varying exposure dose, wind velocity and humidity, although the temperature has a negative effect on the SRs. Adjusted SRs related with temperature were introduced. The indoor BTX concentrations measured with THPDS and a commonly used active sampling method in seven real indoor environments show great agreement with R² ≥ 0.97 (p < 0.0001). The uncertainties of the diffusive sampling method for benzene, toluene and xylenes are 21.5%, 23.3% and 16.9%, respectively, and conform to the requirements of Chinese national standard, NIOSH protocol and EN 482. It is concluded that the uncertainties of THPDS are comparable to those of most commercial passive samplers.