Air pollution may trigger appendicitis, research suggests.
Scientists made the discovery after comparing local pollution data with hospital admissions in Calgary, Canada. They found correlations between high levels of ozone and nitrogen dioxide and appendicitis incidence. More men than women were found to be affected.
The researchers looked at data on 5,191 adult patients admitted to hospital with appendicitis in Calgary. More than half occurred between April and September, the warmest months of the year in Canada when people are most likely to be outside.
The findings, reported in the Canadian Medical Association Journal, may help explain historic appendicitis trends, the scientists believe.
Appendicitis incidence soared in industrialised countries during the 19th and early 20th centuries, but decreased with the introduction of laws to improve air quality. However, it has been growing in developing countries as they become more industrialised.
Dr Gilaad Kaplan, one of the researchers from the University of Calgary, said: "For unexplained reasons, men are more likely than women to have appendicitis. Men may be more susceptible to the effects of outdoor air pollution because they are more likely to be employed in outdoor occupations."
Inflammation triggered by pollutants may be one reason why air quality can affect the appendix, say the researchers. The appendix is a worm-like organ attached to the large intestine with no known function in humans.
Appendicitis occurs when the appendix becomes swollen and inflamed, causing acute pain, fever and vomiting.