Behavior-weighted wearable passive sampling of personal airborne phthalate exposure among university students

Phthalates (PAEs), widely used plasticizers in indoor materials, are semi-volatile organic compounds with potential adverse health effects. Conventional stationary sampling methods inadequately capture exposure variability linked to individual behaviors and personal microenvironments. This study introduces an activated carbon fiber-based wrist-worn passive sampler and establishes a behavior-weighted calibration framework that integrates static and dynamic conditions to reconstruct personal airborne PAE concentrations among university students. Sampling rates (SRs) were calibrated under static (horizontal placement) and dynamic (anterior-posterior and medio-lateral swinging) conditions to account for realistic behavioral patterns and wearing conditions, with behavioral weighting derived from wrist kinematics recorded via Xsens DOT sensors. Dynamic motion modified SRs in a compound-specific manner, with higher SRs observed for diisobutyl phthalate and di-n-butyl phthalate (DnBP), but not consistently for all PAEs. During a 21-day deployment among 27 students, the median concentration of Σ₁₀PAEs was 252 ng/m³, dominated by di(2-ethylhexyl) phthalate (DEHP), DnBP, dimethyl phthalate, and diethyl phthalate. Females had higher median concentrations than males, and personal care product use frequency correlated positively with selected PAE concentrations. Monte Carlo simulation indicated that the estimated daily inhalation intake of Σ₁₀PAEs was approximately 1.85 times higher among females than among males, with DEHP contributing the largest proportion in both groups. Sensitivity analysis identified accumulated pollutant mass as the dominant contributor to model output variance, whereas physiological parameters and wearing duration made secondary, compound-dependent contributions. These findings highlight the importance of incorporating individual activity patterns into passive sampling frameworks to obtain more realistic estimates of personal airborne exposure.