Indoor surfaces have an unexpectedly strong ability to absorb and hold harmful chemical compounds that can threaten human health for as long as a year, according to new research.
In the study, air chemistry researchers at the University of California, Irvine, quantified how various indoor surfaces absorb volatile organic compounds (VOCs), which can result in unhealthy conditions for people and animals when inhaled or absorbed through skin contact.
The sources of VOCs are many, such as cooking, spray cleaning, personal care and other consumer products. Other contributors include tobacco smoke and air pollution caused by wildfires. The researchers note that health risks come from inhaling compounds when they “off gas” from surfaces and through dermal uptake when contaminated surfaces are touched.
In the spring of 2022, co-author Jonathan Abbatt, professor of chemistry at the University of Toronto, led the Chemical Assessment of Surfaces and Air study, which utilized simulation chambers in the National Institute of Standards and Technology’s Net-Zero Energy Residential Test Facility. Contaminants were injected into a structure mimicking a home environment, with typical building materials. The research team used mass spectrometry instruments to track the movement and persistence of VOCs in the controlled indoor environment.
“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, who was responsible for modeling observations and is a 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 study, thin organic films with nanometer thickness were thought to be main surface reservoirs. However, this work proves that permeable and porous materials such as painted surfaces, cement and wood are likely the major surface reservoirs in a home.
The research explains why certain odors and contaminants persist indoors even after their sources are removed. For example, it provides scientific evidence for why tobacco smoke odours linger in rooms long after smoking has stopped: The residual compounds, known as “thirdhand smoke,” slowly partition back into the air from surface reservoirs.
