Trees play role in production of smog.

• Position: The Environment - Brief article

After years of scientific uncertainty and speculation, researchers at the University of North Carolina, Chapel Hill, show exactly how trees help create one of society's predominant environmental and health concerns: air pollution.

It long has been known that trees produce and emit isoprene, an abundant molecule in the air known to protect leaves from oxygen damage and temperature fluctuations. However, in 2004, researchers, contrary to popular assumptions, revealed that isoprene likely was involved in the production of particulate matter, tiny particles that can get lodged in lungs, lead to lung cancer and asthma, and damage other tissues as well as the environment--but exactly how was anybody's guess.

Jason Surratt, assistant professor of environmental sciences and engineering, reveals one mechanism by which isoprene contributes to the production of these tiny, potentially health-damaging particles.

His study found that isoprene, once...