Transport of cyclic volatile methylsiloxanes in residence due to the use of personal care products.

Summary

Using field measurements and a mass transfer model that accounts for surface adsorption/desorption, the authors quantified indoor D5 emissions from personal care product use in an occupied residence. The model accurately predicted D5 peaks across days, and feature-importance analysis identified air exchange rate as the dominant determinant over temperature and humidity.

Key Findings

• Developed a mass transfer model of D5 emissions from skin lipids that includes surface adsorption/desorption.
• Long-term residential field monitoring observed repeated D5 concentration peaks after personal care product use.
• Hybrid optimization using enhanced-ventilation experiments yielded parameters enabling accurate day-to-day prediction.
• Feature-importance analysis identified air exchange rate as the primary driver of indoor D5 levels, outweighing temperature and humidity.

Clinical Implications

For clinicians advising patients on indoor air quality or sensitive populations (e.g., asthma), emphasizing ventilation during/after personal care product use and considering lower-D5 formulations may reduce exposure.

Limitations

• Single-residence study may limit generalizability across building types and occupant behaviors.
• Model focused on D5; extrapolation to other cVMS or complex product mixtures requires validation.

Future Directions

Validate the model across varied residences and climates, expand to other cVMS and formulation matrices, and test mitigation strategies (ventilation schedules, product reformulation).