by Olivia Wrigley
Dampness in homes supporting aqueous chemistry could be a contributing factor to adverse health effects, Barbara Turpin investigates.
US researchers are exploring to what degree dampness in homes alters the chemistry and composition of the indoor air[1]. The chemicals formed on wet indoor surfaces could be partially responsible for the increased respiratory symptoms seen in damp homes[2], an effect that has never been fully explained by mold and mildew, they say. In the US, up to 50% of buildings are estimated to be damp.
Barbara Turpin and her team at the University of North Carolina have taken a four-step approach towards confirming this theory. First, they measured the total water-soluble organic gases (WSOGs) present inside and directly outside 13 typical US residential homes – becoming the first team to do so. Water-soluble gases in the air were collected into water, using a mist chamber, and the total carbon collected determined. Concentrations of WSOGs were found to be 15 times higher indoors than outdoors. They note that aqueous chemistry does alter the composition of outdoor air. Indoors, not only are WSOG concentrations higher but surface areas for indoor chemistry are also higher, with indoor surface area: volume ratios greater than 3m2/m3 versus less than 0.1m2/m3 in outdoor air.
Next, the team scanned the literature for WSOGs that have previously been measured inside US homes. These include the carcinogen formaldehyde and the endocrine-disrupter bisphenol A (BPA). The team then predicted other WSOGs that may be present from direct emissions such as from cooking and fireplaces and formed from indoor chemistry. Finally, using literature insight from the outdoor atmospheric chemistry community, the team predicted how these WSOGs would likely react and what they might form. Turpin has previously extensively looked into WSOG reactions occurring outside in clouds and fog[3].
Turpin has found clear evidence that dampness can in fact alter indoor air composition. Damp surfaces may in some cases be a sink and in other cases be a source of WSOGs (e.g., on air conditioner ducting, coils and condensate). Although these conditions may be harmful to our respiratory and other health, Turpin clarified that the degree to which WSOGs and their reaction products contribute to adverse health effects is still unknown.
Turpin has now turned her attention to identifying the chemical reaction pathways of WSOGs in the presence of water.
[1] Duncan, S. M., Sexton, K. G. and Turpin, B. J. Oxygenated VOCs, aqueous chemistry and potential impacts on residential indoor air chemistry. Indoor Air. 2018;28:198–212.
[2]Gunnbjörndóttir, M. I., Franklin, K. A., Norbäck, D. et al. Prevalence and incidence of respiratory symptoms in relation to indoor dampness: the RHINE study. Thorax. 2006;61:221–225.
[3] For example: Blando, J., D. and Turpin, B., J. Secondary organic aerosol formation in cloud and fog droplets: a literature evaluation of plausibility. Atmospheric Environment. 2000;34:1623–1632.