Contributions of Cleaning Solution Residues to Indoor Organic Surface Films

Abstract

Indoor surfaces become coated with a thin organic film that plays important roles in indoor chemistry. The sources for these films are important to understand to improve our ability to model and predict the impacts of the films on indoor air quality. However, the majority of measurements have focused on semivolatile organic compounds. Here, we collected indoor surface films using a surface solvent extractor to enable the characterization of a wider range of organic chemicals present in the films. Surfaces sampled in different academic buildings contain residues from cleaning solutions including both ionic and non-ionic surfactants. These chemicals can be found on smooth impermeable surfaces even after wiping the cleaning solution off the surface. The chemicals may also potentially be deposited on surfaces farther away after spraying the cleaning solutions because many cleaning solutions have a spray applicator that generates aerosols with a bimodal number size distribution. These results demonstrate that a wider range of chemicals should be considered to contribute to indoor surface films and that the idea of a "cleaned surface" should be re-evaluated among laboratory studies, field studies, and models from the standpoint of organic indoor film formation and growth.