In-situ sampling method to measure interface pollutants concentrations of volatile organic compounds from building materials

Volatile organic compounds (VOCs) emitted by building materials pose severe health risk. It is critical to identify major pollution sources for consequent intervention. An in-situ sampling method is introduced in this study to determine solid–gas interface concentrations of building materials to help realize source apportionment with minimal disturbance and cost. The method is featured as an upended cylindrical chamber with two openings. A sampling flow rate lower than a critical value allows diffusion-controlled environment in the chamber and concentration equilibrium between building surfaces and the air. It is validated by tests under various sampling flow rates (difference of 2%–11%) and in an enclosed chamber (difference of 4.7%–14%). Flow field analysis shows that air speed in the chamber is lower than 0.001 m/s and Reynolds number is smaller than 0.5, confirming the diffusion nature. Results indicate that a chamber with large bottom area and/or low height could have high acceptable sampling flow rate, which would reduce sampling time needed. A field test demonstrated that the method can reasonably help reconstruct pollution field and capture interface concentrations change along with temperature. The proposed in-situ method could facilitate better diagnose indoor air pollution by quantifying source contributions.