Numerical Simulations of Synthetic Ester Hydrolysis in the Indoor Environment

Abstract

The hydrolysis of synthetic esters (SEs), including phthalates and adipates, in damp indoor environments can lead to the release of volatile organic compounds implicated in poor air quality and acute health impacts, known as sick building syndrome (SBS). We have adapted the multiphase atmospheric chemistry box model, GAMMA, to simulate SE hydrolysis occurring in surface films in the indoor environment, along with multilayer boundary layer mass transfer and ventilation, in order to investigate this phenomenon on a process level. We then applied the model to analyze three scenarios in which hydrolysis has been hypothesized to have a significant impact on indoor air quality. Simulation results suggest that: (1) alkaline hydrolysis of bis(2-ethylhexyl) adipate (DEHA) and bis(2-ethylhexyl) phthalate (DEHP) from PVC flooring on damp surfaces alone is not sufficient to explain the levels of 2-ethylhexanol reported in indoor air during episodes of SBS; (2) acute exposure to isobutyric acid (IBA) and 2,2,4-trimethyl-1,3-pentanediol (TMPD) may be of concern during and shortly after the application of latex paint on an alkaline surface; and (3) alkaline hydrolysis of SEs following their gas-phase uptake in aqueous films is not expected to generate considerable amounts of acids and alcohols associated with SBS.