Emissions of DEHP from vehicle cabin materials: parameter determination, impact factors and exposure analysis

Abstract

Semi-volatile organic compounds (SVOCs) are widely used in materials employed in vehicle interiors, causing poor in-cabin air quality. The emission characteristics of SVOCs from vehicle cabin materials can be characterized by two key parameters: the gas-phase SVOC concentration adjacent to the material surface (y₀) and the convective mass transfer coefficient across the material surface (h_m). Accurate determination of y₀ and h_m is fundamental in investigating SVOC emission principles and health risks. Considering that the steady state SVOC concentration (y) in a ventilated chamber changes with the ventilation rate (Q), we developed a varied ventilation rate (VVR) method to simultaneously measure y₀ and h_m for typical vehicle cabin materials. Experimental results for di(2-ethylhexyl)phthalate (DEHP) emissions from test materials indicated that the VVR method has the merits of simple operation, short testing time, and high accuracy. We also examined the influence of temperature (T) on y₀ and h_m, and found that both y₀ and h_m increase with increasing temperature. A theoretical correlation between y₀ and T was then derived, indicating that the logarithm of y₀T is linearly related to 1/T. Analysis based on the data from this study and from the literature validates the effectiveness of the derived correlation. Moreover, preliminary exposure analysis was performed to assess the health risk of DEHP in a vehicular environment.