2025-09-22 カリフォルニア大学アーバイン校（UCI）
＜関連情報＞
- https://news.uci.edu/2025/09/22/indoor-surfaces-act-as-massive-sponges-for-harmful-chemicals-uc-irvine-led-study-shows/
- https://www.pnas.org/doi/10.1073/pnas.2503399122
住宅へのVOC注入実験が屋内環境における大規模表面貯留層の存在を明らかに VOC injection into a house reveals large surface reservoir sizes in an indoor environment
Jie Yu, Pascale S. J. Lakey, Jenna C. Ditto, +8 , and Manabu Shiraiwa
Proceedings of the National Academy of Sciences Published:September 22, 2025
DOI:https://doi.org/10.1073/pnas.2503399122
Significance
Organic contaminants partition to indoor surfaces, giving rise to human exposure via dermal uptake and nondietary ingestion pathways. However, the total partitioning capacity of indoor surfaces has not been experimentally quantified in the built environment. By injecting various organic contaminants into the air of a test house, we determine the degree to which these contaminants partition to indoor surfaces. Our estimates of the total surface partitioning capacity are much larger than if the reservoirs are taken to be thin organic films on smooth, impermeable surfaces. This directly affects assessments of how humans are exposed to contaminants that undergo partitioning between indoor air and surfaces.
Abstract
The total partitioning capacity of indoor surface reservoirs determines the mechanism by which humans receive nondietary exposure to organic contaminants, via inhalation, dermal uptake, and dust ingestion. And yet, this capacity is largely unknown. Surface organic films are ubiquitously present but have very low partitioning volume being only 10’s of nanometer thick, whereas other surface reservoirs such as building materials and furnishings can be permeable or porous with large surface areas at the molecular level. Here, we assess the total partitioning capacity of volatile organic compounds (VOCs) in an indoor environment from the measured kinetics of VOC surface uptake after injection of compounds with variable volatility into a well-characterized, unoccupied test house. We show that the size of the indoor surface reservoirs is very large with an octanol-equivalent average thickness on the order of micrometers, indicating that permeable/porous materials such as painted surfaces and wood are likely the major surface reservoirs in the house rather than organic surface films. Large surface reservoirs result in compounds with octanol-air partition coefficients (KOA) larger than 105 being predominantly partitioned to indoor surface reservoirs, making them hard to be removed via ventilation. This result significantly impacts our understanding of VOC fate and human exposure in indoor environments. With such a large partitioning capacity, organic contaminants will have much longer indoor residence times than previously predicted.
