Formation kinetics of SVOC organic films and their impact on child exposure in indoor environments

Zhuo Chen; Yilun Gao; Fanxuan Xia; Chenyang Bi; Jinhan Mo

doi:10.1016/j.scitotenv.2023.168970

Formation kinetics of SVOC organic films and their impact on child exposure in indoor environments

Sci Total Environ. 2024 Feb 20:912:168970. doi: 10.1016/j.scitotenv.2023.168970. Epub 2023 Dec 2.

Authors

Zhuo Chen¹, Yilun Gao¹, Fanxuan Xia¹, Chenyang Bi², Jinhan Mo³

Affiliations

¹ Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Department of Building Science, Tsinghua University, Beijing 100084, China.
² Aerodyne Research Inc., Billerica, Massachusetts, 01821, USA.
³ College of Civil and Transportation Engineering, Shenzhen University, Shenzhen 518060, China; Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Department of Building Science, Tsinghua University, Beijing 100084, China; Key Laboratory of Coastal Urban Resilient Infrastructures (Shenzhen University), Ministry of Education, Shenzhen 518060, China; Key Laboratory of Eco Planning & Green Building (Tsinghua University), Ministry of Education, Beijing 100084, China; State Key Laboratory of Subtropical Building and Urban Science, Guangzhou 510641, China. Electronic address: mojinhan@szu.edu.cn.

PMID: 38043806
DOI: 10.1016/j.scitotenv.2023.168970

Abstract

We conducted an SVOC mass transfer and child-exposure modeling analysis considering the combined sorption of multiple SVOCs containing DnBP, BBP, DEHP, DINP and DINCH in indoor environments. A mechanistic model was applied to describe the organic film formation, and a partition-coefficient-prediction model was originally developed for the realistic organic films. The characteristics of film formation on impermeable surfaces were examined based on three different assumptions: the widely-used constant K_ns,im assumption, K_oa assumption, and the proposed K_om assumption (predicted specifically for the realistic organic films in this study). After long-term SVOC sorption, the organic film reached increasing equilibrium gradually under constant K_ns,im assumption. While under K_oa and K_om assumption, organic films exhibited nearly linear increases on surfaces, the trends of which agreed well with field studies. However, the film thicknesses calculated under K_om assumption with larger film partition coefficients were approximately twice larger than those under K_oa assumption. Meanwhile, Horizontal surfaces with higher deposition rates of particle-phase SVOCs exhibited larger velocities of film growth compared to vertical surfaces. Under the K_om assumption, exposures of hazardous SVOCs for a 3-year-old child increased by 87.5 %-198.7 % even with the weekly cleaning of indoor impermeable surfaces, carpet and cloth. This study is anticipated to provide valuable insights into the film-forming characteristics of multiple SVOCs and the accompanying significant health risks to human beings in indoor environments.

Keywords: Exposure assessment; Indoor air quality; Organic film; Partition coefficient; Semivolatile organic compounds.