Dr. Gilaad G. Kaplan of the University of Calgary and colleagues identified more than 5,000 adults who were hospitalized for appendicitis in Calgary from 1999 to 2006. The team used data from Environment Canada's National Air Pollution Surveillance monitors that collect hourly levels of ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide and particulate matter of varying sizes.

Regression analysis was used to evaluate whether short-term daily changes in air pollution levels were related to the development of appendicitis.

When researchers compared the five-day average of ozone concentrations prior to admission to the hospital, patients were approximately 15 percent more likely to be hospitalized for appendicitis on days of highest ozone concentrations compared to days of lowest ozone concentrations. Similar findings were seen for sulfur dioxide, nitrogen dioxide, and particulate matter, though with lower effect.

The findings were presented at the 73rd annual scientific meeting of the American College of Gastroenterology in Orlando, Fla.