VOCs from vehicle interior materials in a transport microenvironment: time-resolved emissions, exposure windows, and mitigation relevance

Vehicle cabins represent a confined transport microenvironment where emissions from interior materials can contribute substantially to occupant exposure to volatile organic compounds (VOCs), particularly during early use and under low-air-exchange conditions. We compared VOC emissions from two widely used seat upholstery materials, genuine leather and microfiber leather, using a 1 m³ emission chamber. Test pieces with an exposed area of 0.40 m² (40 × 100 cm) were placed in the chamber, and air samples were collected at 2 h, 8 h and 24 h to capture early-use conditions, within-day build-up and a full-day exposure window. VOCs were quantified by preconcentration GC–MS targeting 116 compounds with internal and external standard calibration. The sampled aliquot per injection (20 µL) was negligible relative to the chamber volume, supporting quasi-static conditions.

The two materials exhibited clear differences in both total quantified VOC burden and chemical composition over 2–24 h. Genuine leather showed higher concentrations at later time points, increasing from 117 ppb at 8 h to 171 ppb at 24 h. The profile was dominated by oxygenated VOCs with monotonic increases over time; acetone and isopropyl alcohol each approached 75 ppb by 24 h, consistent with sustained release and accumulation under sealed conditions. In contrast, microfiber leather maintained a lower but comparatively stable total VOC level (64–73 ppb across 2–24 h) while showing an aromatic-dominated feature: toluene remained consistently elevated (18–20 ppb) throughout the period, substantially higher than in genuine leather (3–6 ppb). Time-series behavior further differentiated compound classes, with oxygenated species generally exhibiting accumulation-type trends, whereas selected ester-like compounds displayed faster decay consistent with short-lived volatilization.

These results highlight that compound-resolved, time-resolved measurements can distinguish material-specific emission fingerprints and identify exposure-relevant windows that are not apparent from bulk VOC metrics alone. Ongoing experiments extend the same framework to heat-loading (solar-load) and ventilation-representative conditions to quantify temperature and air-exchange sensitivity of in-cabin VOC exposure.