A Rutgers School of Public Health adjunct professor and his colleague, have developed a model for the growth of organic films on impermeable indoor surfaces, such as windows. Organic films are formed from the organic compounds, or indoor air pollutants, found in indoor air. Some of these compounds stick to indoor surfaces, creating organic films on windows, mirrors, glass plates, hard floors, countertops and other impermeable surfaces. While many films found on surfaces don’t pose human health risk, more information is needed to improve estimates of human exposure to organic films and to aid in the mitigation of potentially unhealthy exposures.

[Photo: Dr. Charles J. Weschler]

Dr. Charles J. Weschler, adjunct professor in the department of environmental and occupational health and member of the Rutgers Environmental and Occupational Health Science Institute, and Dr. William W. Nazaroff, professor of civil and environmental engineering at the University of California, Berkley, found that film growth is driven by the gas-phase concentration of semi-volatile organic compounds (SVOCs) with vapor pressures between 4 x10^-9 and 4 x 10^-12 atm. Films’ thickness can typically range of 10 to 30 nm, depending on how long the surface has been exposed to indoor air since its last cleaning. Surfaces that may be chemically different from one another when clean become similar to one another when covered with organic films; this leads many indoor surfaces to be similar to one another. When a human occupant touches film-covered surfaces, the organics in the film can be transferred to skin or clothing and subsequently absorbed through the skin or ingested through hand-to-mouth activity.

“Organic films pose a risk to human health because some of the chemicals found in the films may be irritating or toxic, depending on the composition of indoor air,” according to Dr. Weschler. “Cleaning of surfaces will reduce the potential for transfer of potentially harmful chemicals from films to skin.”

While the model provides a better understanding of indoor organic films, from a public health perspective, the model may help mitigate unwanted exposure to films that contain chemicals that are rapidly absorbed by the skin (e.g., certain phthalates, nicotine). The model also helps us better understand the components of indoor air pollution because organic films are made up of pollutants found in the air.

“Growth of Organic Films on Indoor Surfaces” was published in the journal Indoor Air.