Spatial distribution of formamide from EVA foam mats: CFD simulation and inhalation exposure assessment for children

Formamide is classified as a Category 1B reproductive toxicant by the European Chemicals Agency. It can be emitted from EVA foam mats in indoor environments. We used ANSYS FLUENT to simulate the spatial diffusion of formamide from EVA mats and estimate children’s inhalation doses at various breathing heights. The CFD model passed mesh-independence tests and was validated against experimental data. We quantified formamide mass fractions and velocity fields across different pre-volatilization durations and air velocities. We also assessed exposures for supine, crawling, sitting, and standing postures. Results show that (1) lower breathing heights (supine, crawling) yield substantially higher concentrations and inhalation doses than standing height; (2) concentrations decline with increasing pre-volatilization duration, indicating that pre-use off-gassing reduces exposure; and (3) concentrations decrease as air velocity increases, indicating that improved ventilation lowers indoor levels. Quantitatively, at Z = 0.15 m, the mass fraction decreased by 8.05% by day 15 and a further 6.57% by day 25 relative to day 10 (≈ 14% cumulative). At Z = 0.175 m, mass fraction decreased by 54.45% and 82.90% when air velocity increased to 0.2 and 0.5 m·s-1 , respectively. Estimated exposure concentrations (0.15–0.49 mg·m-3) produced inhalation doses for 0–3-year-olds during crawling on the order of hundreds of μg·kg-1·d-1 . These findings provide spatially explicit exposure data to inform inhalation exposure assessments and targeted mitigation measures in indoor scenarios involving EVA foam mats.