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Impacts of Indoor Chemical Pollution Remain Mostly Invisible

measuring emissions from stir fry
HOMEChem researchers measured emissions from cooking a stir fry in one experiment. | Callie Richmond

Furniture, flooring, construction materials, and humans and their habits are just some sources of the thousands of particles and gases that surround people living indoors. As scientists collect increasingly sophisticated data on the chemistry of the indoor environment, policymakers and industry leaders are seeking more information on how to apply these findings to buildings and homes, experts said at an American Association for the Advancement of Science symposium.

The term "environment" has a specific "outdoor" meaning for many policymakers and the public that has overshadowed the hazards of the indoor environment for pollution and human health, speakers at the event suggested. Such indifference exists even as Americans spend 70 years of an average 79-year life span inside. While the U.S. Environmental Protection Agency is the most prominent regulator of outdoor pollution, research and policy decisions about the indoor environment are spread across several federal agencies.

It may be time for a "national chemistry of the indoor environment initiative, similar to what we have done with the national nanotechnology initiative," said Vicki Grassian, a professor of physical chemistry at the University of California, San Diego, who moderated the closing session at the Sept. 19 symposium.

"Bridging agencies that have different interests but around the same subject is something that is needed … and would be a very welcome policy change," to fund multidisciplinary research projects related to the indoor environment, agreed Richard Corsi, dean of the Maseeh College of Engineering and Computer Science at Portland State University in Oregon. Corsi and other symposium participants also spoke at a related Capitol Hill briefing held Sept. 18 for congressional staff members.

The symposium and briefing were organized by AAAS's Research Competitiveness Program in collaboration with the Alfred P. Sloan Foundation to facilitate "a new vision for what this transdisciplinary field of research has achieved and can achieve," said Charles Dunlap, the program's director.

Since 1996, the Research Competitiveness Program has worked to build research capacity in science, technology, engineering, and mathematics by evaluating STEM education programs, helping design and manage peer review competitions, and supporting innovation and entrepreneurship in 130 emerging economies around the world.

As part of the program, "we mobilize experts and bring them together to increase research capacity in a variety of ways," said Annette Olson, an RCP project director at AAAS who led the organization of the events. "For this symposium, we sought to bring together experts in indoor chemistry with potential collaborators who could help fund the research moving forward or create new, multidisciplinary research efforts, as well as with agency and industry stakeholders who would be the ones implementing this knowledge directly. In addition to the speakers and moderators, representatives from 55 organizations were able to attend the symposium."

At the events, experts shared studies that offer a detailed look at the thousands of chemicals and chemical reactions inside buildings, apartments, and homes. Surface areas provided by furniture materials such as polyurethane foam, wall paints, and flooring offer complex, dynamic surfaces that both leach and absorb chemicals and provide a place for dynamic chemical reactions. Although exposure to some chemicals, including flame retardants and plasticizers, has been linked to the risk of certain cancers and developmental effects in children, many indoor compounds have not been identified or evaluated for their health impacts, the researchers said.

For instance, there are "about 30,000 different chemicals in indoor dust — and we only know about 280 of them," said Heather Stapleton, an associate professor of exposure science and environmental health at Duke University. "I spend a lot of time and money just trying to figure out what's in consumer products, particularly the flame retardants in polyurethane foam. Yet that information is available within the industry, but unfortunately they're not required to release that information to the public. They're allowed to maintain confidential business information indefinitely."

Laura Kolb, EPA's Indoor Environments Division director for scientific analysis, said that more research would better define the risks of indoor chemicals. "I need to know what the implications for public health are, so I can translate it into EPA guidance," she said.

Several symposium participants suggested that the health impacts of chemicals in the indoor environment are still mostly invisible to the public. In his plenary address, Mahesh Ramanujam, president and chief executive officer of the U.S. Green Building Council and Green Business Certification, Inc., cited studies from the Harvard T. H. Chan School of Public Health and others that "found that improved indoor environmental quality can double occupants' cognitive function scores and occupants had increased decision-making performance scores."

Despite this, many people do not know that "green buildings — or buildings at all — can contribute to health and wellness," said Ramanujam.

Health disparities related to the indoor environment are another aspect of the field that deserves more attention, some researchers noted. In one of Stapleton's studies, for instance, children living in public housing with all vinyl flooring had levels of benzyl butyl phthal­ate plasticizer in their urine that were 15 times higher than children from homes with no vinyl flooring. Lesliam Quirós-Alcalá, an assistant professor of environmental health and engineering at Johns Hopkins Bloomberg School of Public Health, discussed how pest control practices in low-income housing could lead to increased levels of pesticide exposure for residents.

As scientists study the chemical contents of the indoor environment, their findings also suggest ways to reduce toxic chemical exposures. When Corsi and Glenn Morrison, a professor of environmental sciences and engineering at the University of North Carolina, studied how methamphetamines penetrate wallboard, they found that higher humidity could drive the chemicals off the surface. "If we understood this process a little better," Corsi said, "it might be possible to reduce exposure to indoor pollutants like volatile organic compounds by simultaneously flushing the building while adjusting its temperature and humidity."

To control indoor pollution, researchers also need to know more about human behavior, Corsi noted. "Trying to understanding why some people don't use the exhaust fan on their stove when they cook, or why some people like to burn a lot of incense or why some people like to vacuum 10 times a week as opposed to once a month … all of this affects what people are exposed to indoors."

Connecting research to action is possible and necessary, said Marina Eller Vance, an assistant professor of mechanical engineering from the University of Colorado. Vance shared some of her results from HOMEChem, an ongoing research collaboration that examines the chemistry of the indoor environment in a manufactured "test house" at the University of Texas, Austin.

"Sometimes I feel like I hear that we are powerless to change or to impact people's exposure to indoor pollutants because we can't control what people do within their own homes, but that's not true," she said. "We can educate and interact with industry to make those changes happen upstream in the supply chain."

[A version of this article was published in AAAS News & Notes in the Nov. 29, 2019 issue of Science.]

[Credit for associated image of HOMEChem experiment: Callie Richmond]