By Sarah Haines, PhD Candidate, The Ohio State University, @SarahRHaines

Scanning Electron Micrograph
Image by Nicholas Nastasi


We are excited to announce the recent publication of our paper, titled “Modeling microbial growth in carpet dust exposed to diurnal variations in relative humidity using the “Time-of-Wetness” framework”  in the journal Indoor Air. This work is a culmination of research investigating how changes in relative humidity impact microbial growth in carpet dust. A related study was recently completed which found that moisture is typically the most important factor contributing to fungal growth in carpet. Carpets can trap dust and provide a reservoir for microbial growth. Resuspension of this dust contributes to human microbial exposures and may be associated with increasing asthma exacerbations and fungal allergen exposures.

This newly published study found that even after short (6 hour), repeated periods of elevated (>80%) relative humidity, fungal growth in carpet was sustained. These conditions could potentially result from a showering event or other similar occurrences in homes, even if the typical relative humidity levels are within the EPA recommended range of 30-50%. This microbial growth also likely has important implications for indoor chemistry.

This recent article is foundational for the ongoing project “Chemistry of Homes: Environmental Microbes and Moisture” (CHEMM), which is currently analyzing how variations in relative humidity impact microbial production of chemical volatile organic compounds. Carpet and dust are incubated at cycling relative humidity conditions over a period of 2 weeks. The samples are then “sniffed” using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS) which can measure a variety of volatile organic compounds at a 1 second time resolution. The results will have important implications for further understanding the relationship between short bursts of elevated relative humidity and MVOC emissions in the home.

Manuscript Author information:

Sarah R. Haines
PhD Candidate, The Ohio State University
Twitter: @SarahRHaines

Jeffrey A. Siegel
Professor, University of Toronto
Twitter: @IAQinGWN

Karen C. Dannemiller
Assistant Professor, The Ohio State University
Twitter: @KarenCDannemill


Additional CHEMM investigators:

Rachel I. Adams
Project Scientist, University of California – Berkeley
Twitter: @Rachel_I_Adams

Pawel K. Misztal
Assistant Professor, The University of Texas at Austin
Twitter: @MisztalPawel