New York, Mar 9 (IANS): Do you believe smoking hookah is safer than smoking cigarettes? Think twice.

A single session of hookah can lead to greater exposure to carbon monoxide than smoking a single cigarette, and causes harm to the heart and blood vessels, say researchers including one of an Indian-origin.

The findings showed that during a hookah smoking session that typically lasts for 30 or more minutes, users inhale many litres of smoke filled with large quantities of particulate matter at higher concentrations.

Even short-term exposure to carbon monoxide in hookahs is toxic and can interfere with exercise capacity.

Hookah smoke also contains other harmful chemicals including nicotine, air pollutants, volatile organic chemicals, polycyclic aromatic hydrocarbons, acrolein, lead, cadmium and arsenic that can affect the cardiovascular system.

Most of these toxins are higher in hookah than cigarette smoke, said the study published in the journal Circulation.

"Many young people mistakenly believe that smoking tobacco from a hookah is less harmful than cigarette smoking because the tobacco if filtered through water, but there is no scientific evidence that supports that claim," said Aruni Bhatnagar, Professor at the University of Louisville in the US.

Bhatnagar noted that hookah smoking is addictive and can lead to the use of other tobacco products such as cigarettes.

Unlike cigarette tobacco, hookah tobacco, often colourfully packaged, is sold in candy and fruit flavours, which appeals to younger audiences.

In addition, because many people smoke hookah in lounges and cafes it is perceived to be a social activity and less habit-forming.

While several youth are aware of the risks associated with cigarette smoking and avoid it, there is a misperception among hookah users that this method of tobacco use is harmless.

It is also because most of the tobacco marketed to hookah users does not carry a health warning, leading to the misperception that it is not harmful, the researchers said.