Dampness affects a substantial percentage of homes and is associated with increased risk of respiratory ailments; yet, the effects of dampness on indoor chemistry are largely unknown. We hypothesize that the presence of water-soluble gases and their aqueous processing alters the chemical composition of indoor air and thereby affects inhalation and dermal exposures in damp homes. Herein, we use the existing literature and new measurements to examine the plausibility of this hypothesis, summarize existing evidence, and identify key knowledge gaps. While measurements of indoor volatile organic compounds (VOCs) are abundant, measurements of water-soluble organic gases (WSOGs) are not. We found that concentrations of total WSOGs were, on average, 15 times higher inside homes than immediately outside (N = 13). We provide insights into WSOG compounds likely to be present indoors using peer-reviewed literature and insights from atmospheric chemistry. Finally, we discuss types of aqueous chemistry that may occur on indoor surfaces and speculate how this chemistry could affect indoor exposures. Liquid water quantities, identities of water-soluble compounds, the dominant chemistry, and fate of aqueous products are poorly understood. These limitations hamper our ability to determine the effects of aqueous indoor chemistry on dermal and inhalation exposures in damp homes. K E Y W O R D Saqueous chemistry, damp homes, human exposure, interfacial chemistry, OVOC, water-soluble organic compounds | INTRODUCTIONDampness in buildings is common in the United States, with estimates ranging from 18% to 50% percent of buildings affected, where buildings were defined as "damp" based on observation of standing water, water-damaged materials, presence of mold, and/ or high measured relative humidity (RH). WSOGs are emitted from indoor sources and formed through oxidation. They will be taken up into liquid water, when present, and subsequently react. Thus, aqueous chemistry could affect exposure by acting as a sink for certain water-soluble gases in indoor air and a source of other volatile products (altering inhalation exposure) and condensed phase products (altering particle inhalation and dermal exposure).This study provides insights into WSOGs likely to be in residential indoor air and examines the potential for aqueous chemistry indoors to alter the chemical composition of this air, with the motivation of further understanding dermal and inhalation exposure

Water-soluble organic gas (WSOG) concentrations are elevated in homes. However, WSOG sources, sinks, and concentration dynamics are poorly understood. We observed substantial variations in 23 residential indoor WSOG concentrations measured in real time in a North Carolina, U.S. home over several days with a high-resolution time-of-flight chemical ionization mass spectrometer equipped with iodide reagent ion chemistry (I-HR-ToF-CIMS). Concentrations of acetic, formic, and lactic acids ranged from 30-130, 15-53, and 2.5-360 μg m −3 , respectively. Concentrations of several WSOGs, including acetic and formic acids, decreased considerably (~ 30-50%) when the air conditioner (AC) cycled on, suggesting that the AC system is an important sink for indoor WSOGs. In contrast to non-polar organic gases, indoor WSOG loss rate coefficients were substantial for compounds with high O:C ratios (e.g., 1.6-2.2 h −1 for compounds with O:C > 0.75 when the AC system was off). Loss rate coefficients in the AC system were more uncertain, but were estimated to be 1.5 hr −1. Elevated concentrations of lactic acid coincided with increased human occupancy and cooking. We report several WSOGs emitted from cooking and cleaning as well as transported in from outdoors. In addition to indoor air chemistry, these results have implications to exposure and human health.

Characterization of residential indoor air showed that organic acids make up a significant portion of water-soluble organic gases.