Iranian researchers identified similar effects on lung function and respiratory symptoms -- including wheeze, cough and chest tightness -- in both water pipe smokers and deep inhalation cigarette smokers.

The study, published in the August issue of the journal Respirology, challenges the widely held belief that smoking through these types of water pipes filters out the toxic components of tobacco.

"Our findings reveal that there were profound effects of water-pipe smoking on lung function values, which were similar to the effects observed in deep-inhalation cigarette smokers," said Dr. Mohammad Hossein Boskabady, of Mashhad University of Medical Sciences, and colleagues in a journal news release.

Researchers compared the lung function of three groups of smokers -- 57 water-pipe smokers, 30 deep-inhalation cigarette smokers and 51 normal-inhalation cigarette smokers -- and a fourth group of 44 nonsmokers.