The influence of indoor environmental factors on toluene uptake rate of a tube-type diffusive sampler

Obtaining effective and reliable uptake rates is crucial for applying diffusive samplers in monitoring indoor gaseous pollutants. Diffusive uptake rates are mainly reported for the workplace and environmental monitoring in a short-term exposure (such as 8 h) at high concentrations or long-term exposure (such as 7d, 14d) at lower concentrations. There are relatively few reports on the 24 h uptake rate and the changes in uptake rate under different environmental conditions. This study explores the influence of indoor environmental factors such as temperature, humidity and concentration on the 24 h toluene uptake rate of Tenax TA diffusive samplers. Fifteen humidity control experimental cases are conducted under three concentration ranges (0.2–0.8 mg/m3, 1–1.5 mg/m3, 2–3 mg/m3) with temperature recorded simultaneously. Through correlation analysis and linear regression, it is found that temperature, humidity and concentration have statistically significant effects on the toluene uptake rate. The increase in temperature and humidity would cause a decrease up to 25.9% and 46.2% in toluene uptake rate respectively, while concentration has a positive impact. Accordingly, an empirical equation is proposed to predict the uptake rate under environmental effects. The reported effect of environmental factors will help obtain the accurate uptake rates of tube-type diffusive samplers for gaseous pollutants.