A Breath of Fresh Air
We spend up to 90 percent of our time indoors but probably don’t give much thought to the quality of the air we breathe until we step outside. That could be a mistake, says Beverly Coleman (M.S.’05, Ph.D.’09 CEE), who received her doctorate just last month.
A specialist in indoor air pollution and the health risk it can pose in homes, offices and even aircraft cabins, Coleman’s research focus at Berkeley Engineering was ozone, the highly reactive gas that is the primary component in smog. When ozone seeps indoors or is created inside, it reacts with household cleaners, air fresheners and other substances to produce a variety of irritating or toxic byproducts. Formaldehyde, a carcinogen, is among the secondary pollutants formed when ozone mixes with chemicals called terpenes, which are found in pine, lemon and orange oils contained in some cleaning and personal hygiene products.
“Ozone is not what you want to be breathing, and you don’t want to breathe the byproducts either,” says Coleman, who studied under William Nazaroff, a Berkeley professor of environmental engineering and leading expert in indoor air quality.
Even the oil on human skin triggers a reaction when it comes in contact with ozone. As part of a study for the Federal Aviation Administration, Coleman discovered that approximately 25 percent of the ozone that enters a closed environment—like an airplane—mixes with the fatty acids on human skin to form byproducts called carbonyls. “That tiny amount of skin oil will react with ozone,” she says. “You get byproducts and they’re right in your breathing zone.” The health effects from these oxygenated volatile organic compounds are not well known, but carbonyls are believed to be irritants and potentially harmful.
In related research, Coleman explored the interaction of ozone with such materials as airline carpet, plastic tray tables and seat fabric, and measured the resulting byproducts. Ozone exposure is of particular concern for airline crew members and others who spend a significant amount of time airborne. Airline cruising altitudes often approach the bottom of the Earth’s ozone layer, and planes use that outdoor air to ventilate their cabins. While aircraft can have ozone converters on board, they’re not always operational, Coleman says. As a result, ozone levels inside planes can be equivalent to levels in such polluted cities as Los Angeles.
“The verdict’s really out” on the health consequences of that exposure, she adds, noting that the National Institute for Occupational Safety and Health (NIOSH) has studied her findings and similar research.
Honoring her work, the FAA’s Centers of Excellence Program named Coleman an outstanding student of the year in 2008. Her graduate research was also recognized last year with the first prize for student achievement from the International Society of Indoor Air Quality and Climate and the Joan M. Daisey Indoor Air Quality Research Award. Of her interest in indoor air, she says, “We all breathe air indoors all day, every day, but so few people study it.” She recently turned her expertise to outdoor air quality, joining Chevron Energy Technology Company in Richmond as an air pollution specialist.
Coleman earned her B.S. in civil and environmental engineering from the University of Texas at Austin in 2003. She began her graduate studies at Berkeley that fall, participating upon her arrival in a groundbreaking indoor air pollution study commissioned by the California Air Resources Board. The four-year investigation led by Nazaroff revealed that common household cleaners and air fresheners can emit pollutants at potentially hazardous levels and showed how some chemicals produce secondary toxic compounds when reacting with ozone. The 2006 report was one of the first to measure emissions and concentrations of primary and secondary toxic compounds produced by these household products under common indoor use conditions.
In experiments at Lawrence Berkeley National Laboratory, Coleman analyzed the ultrafine particles formed by the reaction of ozone with cleaning products and an air freshener containing terpene. While the health effects are not completely understood, “They’re such small particles that, when breathed in, get deep into the lungs and may pass through to the bloodstream,” she says.
Although Coleman originally planned to study art history, after a year at UCLA she missed the math and science she focused on in high school. She ultimately pursued engineering studies in her native Texas and has never regretted her choice. Of her time at Cal, she says, “I loved the experience and the community of people I was with. Engineering is a profession where you really have an impact on people.”