July 13, 1999 Environmental engineers at The University of Texas at Austin have documented that showers and dishwashers contribute to indoor air pollution. When tap water contains even trace amounts of harmful chemicals such as radon, constituents of gasoline, or by-products of drinking water chlorination (disinfection), these chemicals can be transferred from water to indoor air. This process, called volatilization or chemical stripping, adds to a growing list of indoor air pollutants, the air researchers report in the July 1 issue of Environmental Science and Technology.
The researchers, led by Dr. Richard Corsi, associate professor of civil engineering, completed a series of experiments using household appliances: dishwashers, clothes washers, showers, and bathtubs. During each experiment, water used by the appliance contained chemical tracers with properties similar to potentially toxic chemicals found in many public water supplies. Corsi's group determined that significant percentages of all tested pollutants transferred from water to indoor air.
Corsi says that nearly all public water supplies contain at least small amounts of potentially toxic chemicals associated with the chlorination of drinking water, an otherwise beneficial process used to protect the public from pathogenic organisms. Furthermore, inhalation (breathing) exposure to many of these chemicals may rival or exceed exposure due to ingestion (drinking) of the water.
A much smaller number of Americans is exposed to significantly higher levels of harmful chemicals in well water tainted by gasoline from leaking underground storage tanks, or industrial solvents previously spilled on soil.
Dishwashers were observed to be particularly effective at stripping chemicals from water to indoor air, with the bulk of chemicals released when the door is opened after a dishwashing event. Corsi also notes that washing machines and dishwashers using chlorinated bleaches or detergents may increase public exposure to chlorinated chemicals through the formation and volatilization of these additional chemicals.
The U.S. Environmental Protection Agency is currently using the research to assess public exposures to chemicals, and subsequent health risks, once thought to enter the human body primarily through ingestion.
A large number of studies in the past six years have compared indoor/outdoor concentrations of volatile and hazardous air pollutants. "In every single study, with just about any pollutant, you find higher concentrations indoors than outdoors--even in the most polluted cities in the United States," says Corsi.
Trends of the latter half of this century have negatively impacted indoor air quality. Attached garages can bring automobile exhaust and stored chemical vapors inside the house. The energy crisis led to more airtight homes and buildings, allowing pollutants to build indoors.
Several things must happen to appropriately address this issue, says Corsi.
*In general, the public knows more about outdoor than indoor air pollution, and needs to become more educated so they can help to solve their own problems.
*More research is needed to better understand the many sources of hazardous air pollutants that occur in homes, office buildings, and schools.
*Ultimately, sources of indoor air pollution will likely be reduced through the sale of environmentally-friendly (low emitting) building materials and consumer products, as well as public education on ways to reduce exposure to toxic chemicals in the home.
*In the case of volatilization from water, it is important to maintain well-ventilated surroundings during water use. For example, leave the bathroom fan on or window open when showering, use the hood fan above the stove when boiling water, etc. Commercially available activated carbon canisters will remove volatile organic compounds from water prior to their discharge through a faucet or shower head.
"There are a lot of measures the public can take to reduce exposure to such compounds. However, the first step is simply to make sure the public understands the nature of the problem, and the simple steps they can take to solve it," says Corsi.
About UT's College of Engineering: The University of Texas College of Engineering ranks among the top ten public engineering schools in the United States. With the nation's third highest percentage of faculty elected members of the National Academy of Engineering, the College's 6,000 students gain exposure to the nation's finest engineering practitioners. Appropriately, the College's logo, an embellished checkmark used by the first UT engineering dean to denote high quality student work, is the nation's oldest quality symbol. The College maintains a web site at http://www.engr.utexas.edu/.
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