Indoor surfaces in homes can absorb and retain harmful volatile organic compounds (VOCs) for up to a year, according to a study led by researchers at the University of California, Irvine. The findings were published in the Proceedings of the National Academy of Sciences.
The research team quantified how various indoor materials hold onto VOCs, which are chemicals that can be hazardous when inhaled or absorbed through skin contact. Sources of VOCs include cooking, cleaning products, personal care items, tobacco smoke, and air pollution from wildfires. Health risks arise when these compounds are released back into the air or come into contact with people.
The study was part of the Chemical Assessment of Surfaces and Air project led by Jonathan Abbatt, professor of chemistry at the University of Toronto. Using simulation chambers at the National Institute of Standards and Technology’s Net-Zero Energy Residential Test Facility, researchers introduced contaminants into an environment built to mimic a typical home. Mass spectrometry was used to track how long VOCs persisted indoors.
“Scientists in the air chemistry research community have known for a long time that many indoor contaminants can be absorbed by indoor surfaces, but the size of indoor surface reservoirs inside homes and buildings had not been established,” said Manabu Shiraiwa, UC Irvine professor of chemistry and corresponding author on the paper. “Our modeling found that surfaces inside homes have a much greater size to absorb and hold chemicals than previously realized. We can think of these surfaces as massive chemical sponges that soak up VOCs.”
Before this work, it was believed that thin films on surfaces played the main role in storing chemicals indoors. However, this study showed that permeable materials like painted walls, cement, and wood are likely major storage sites for these compounds.
“This discovery has significant implications for human health,” Shiraiwa said. “It means people can be exposed to harmful chemicals long after their initial introduction into indoor spaces, and compounds can later be released back into the air or transferred to humans through direct contact with contaminated surfaces.”
He added: “This result significantly impacts our understanding of VOC fate and human exposure in indoor environments. With such a large partitioning capacity, organic contaminants will have much longer indoor residence times than previously predicted.”
The research also helps explain why certain odors persist indoors even after their sources are removed—for example why tobacco smoke smells linger due to residual “thirdhand smoke” being re-released from surfaces over time.
Findings suggest regular ventilation may not be enough to remove all contaminants; physical cleaning methods such as vacuuming or dusting may also be needed for effective removal.
Other contributors included Pascale Lakey at UC Irvine; Jie Yu and Xing Wang at University of Toronto; Jenna Ditto at Washington University in St. Louis; Han Huynh and Marina Vance at University of Colorado Boulder; Michael Link, Dustin Poppendieck and Stephen Zimmerman at NIST; Delphine Farmer at Colorado State University. The Alfred P. Sloan Foundation provided funding support.
