Researchers with the University of California at Davis reported last week that the air over New York City contained elevated levels of toxic pollutants in the weeks following the September 11 terrorist attacks. Scientists collected air samples approximately one mile from ground zero from October 2 to December 25. Last Monday, they presented results from data collected through October 31.

Researchers involved in the study say very fine particles of substances such as vanadium and sulfur persisted in the atmosphere throughout October. Health officials say the particles can contribute to asthma, emphysema, and other respiratory illnesses. Scientists also discovered lead and mercury in the air samples. The Environmental Protection Agency (EPA) has been accused of misleading the public in the days after the attacks. A week after the tragedy, EPA officials assured New Yorkers that the air "was safe to breathe."