When you cook or clean inside your home, what chemicals are you breathing in that are potentially harmful? Colorado State University chemists have given us a solid start to the answer.
A large, collaborative research experiment that attempted to map the airborne chemistry of a typical home was conducted in 2018 and co-led by Delphine Farmer, associate professor in the Department of Chemistry at CSU. The experiment, called HOMEChem, brought 60 scientists from 13 universities to a lab at the University of Texas at Austin to perform typical household activities such as cooking and cleaning and use sophisticated instruments to document the resulting chemistry. The effort, called HOMEChem, was supported by the Sloan Foundation.
In a new paper at Environmental Science & Technology, the farmer’s team at CSU has taken the vast amounts of data collected during HOMEChem and sorted it according to health effects. They determined how many compounds they observed are known human toxins or, based on newer Environmental Protection Agency models, predicted to be potential human toxins. Most such compounds are emitted in small amounts and can be cleaned up through proper ventilation. But the health effects of both individual compounds and their complex mixtures indoors are not well understood by scientists.
The bottom line; “Indoor air isn’t going to kill you, but we’re finding that indoor air has far more — and often higher levels — of known and potential air toxics than outdoors, particularly when you’re cooking,” Farmer said. , an atmospheric chemist who, prior to this experiment, had spent most of her career measuring more “traditional,” outdoor air toxics.
The data management feat of actually linking the data from HOMEChem to the toxin databases was done by co-author Anna Hodshire, a former CSU postdoctoral researcher skilled in analyzing data from atmospheric instruments.
“I think it’s very interesting that there are so many compounds that are emitted from common household activities and that the majority of these compounds have not been studied from a toxicity standpoint,” Hodshire said. “This does not automatically mean that all of these compounds are toxic – but it does point to the fact that much more work is needed to assess some of the compounds that are often emitted in high concentrations from household activities.”
From the huge variety of compounds measured during HOMEChem, the usual suspects such as benzene and formaldehyde emerged in varying amounts. The lesser-known acrolein, which is a lung toxin emitted by wood and heating fats, came to light as a potential compound of interest for further research, Farmer said. Another compound that emerged from Hodshire’s analysis was isocyanic acid, which has not been well studied and is known to react with proteins in the human body.
The researchers found that the cooking activities produced higher amounts of potentially toxic compounds, similar to some seen in forest fire smoke—which made sense to Farmer, when you consider that a fire is just an “extreme form of cooking.”
Gaps in understanding everyday toxins
Contributing to the body of knowledge about indoor air chemistry through the HOMEChem experiment has given Farmer and her team a new appreciation for how much is lacking in our understanding of our daily exposure to potential toxins.
“We’ve done our part now, and hopefully there’s enough information for others to take the charge and see which compounds are important to study,” Farmer said.
Farmer and collaborator Marina Vance of the University of Colorado Boulder led a follow-up experiment to HOMEChem in 2022 called CASA, which further looked at how chemicals emitted indoors react with surfaces such as floors, walls and furniture. Results from this experiment are forthcoming.
Materials provided by Colorado State University. Originally written by Anne Manning. Note: Content can be edited for style and length.