Apple-scented smoke drifts in the air as the police officer looks around genially. "I get to talk to people here that I otherwise wouldn't ever get to know." One patron looks up from her laptop and nods in agreement. "I'm sure it's not great for you," Alu adds, "but it got me to quit smoking cigarettes."
Although not even hookah fans suggest that smoking tobacco through a water pipe is healthful, many contend that drawing the smoke through the water removes some of the harmful chemicals. Scientists, however, point out that although the hookah might filter out some irritants, the smoke nevertheless contains high levels of nicotine, carbon monoxide and other toxic chemicals. The trouble is, they can't say exactly how unhealthful it is, particularly compared with cigarettes.
The potential risks, or relative safety, of hookah smoking has taken on added relevance as hookah bars have begun to sprout up across the United States in recent years.
There are more than 400 hookah cafes, according to an online database of hookah bars, with half in California, Illinois, New York, Arizona and Florida. California leads the pack with about 90 hookah bars and cafes, and the numbers appear to be growing, says Paul Knepprath, vice president of government relations for the American Lung Association of California. Hookah bars are especially popular among 18- to-24-year-olds, he says.
The growing popularity of hookah bars has led the American Lung Association and the World Health Organization to issue advisories on the dangers of hookah smoking.
"Any of the major diseases that are associated with cigarette smoking are associated with hookah pipe smoking," Knepprath says. The long-term dangers, he says, include lung and heart disease, cancer, emphysema and heightened asthma attacks.
But tell that to hookah smokers, who say the wave of relaxation that comes with every puff, along with the fellowship of other smokers, outweighs the risks.
Typically, a hookah consists of a bowl, which is filled with tobacco, affixed to a hollow tube that extends down into an enclosed jar partially filled with water. The user draws air from a hose affixed to the top of the jar, creating a vacuum in the air and forcing smoke up through the water.
The origins of the hookah are somewhat cloudy, but it has been traced back as far as the 14th century, when water pipes appear to have been used in Africa. By the 17th century, the hookah had spread throughout Turkey, Greece and the Middle East. (It famously made its way into literature in 1865 in the hands of the truculent, hookah-smoking caterpillar in "Alice in Wonderland.")
Today, it's commonly reported that there are an estimated 100 million daily hookah smokers, but the origin of that number isn't clear.
The American Lung Association's Tobacco Policy Trend Alert, released in February, describes hookah smoking as the first new tobacco-use trend of the 21st century. This is particularly disheartening, Knepprath says, because the use of cigarettes and other forms of tobacco has declined dramatically in the past 40 years. "In California, we've reduced tobacco consumption by more than 60 percent just since 1989."
A key sticking point among researchers is the question of just how much nicotine and other dangerous chemicals are contained in hookah smoke, and how much of that is absorbed by the body.
"There's certainly no evidence that it is safer," says Dr. David Burns, professor emeritus of medicine at the University of California, San Diego and a contributor to the WHO report, "and there is evidence that it contains many of the toxic constituents of tobacco. And you may get them in higher doses than you would from smoking cigarettes because of the very large volume of smoke that you ingest." Hookah sessions typically last 20 to 80 minutes, and the mildness of the smoke allows for deeper inhalations.
A World Health Organization Advisory issued in 2005 reports that during one 40- to 45-minute hookah session, a smoker could, in theory, inhale the equivalent of 100 cigarettes. A study in the July issue of Pediatrics found that carbon monoxide concentrations in the blood of hookah smokers was quadruple that of cigarette smokers. And in a 2004 review of hookah studies, lead author Thomas Eissenberg at Virginia Commonwealth University reported that hookah smoke generated by a machine appears to contain substantial amounts of nicotine, arsenic, cobalt, chromium and lead.
Apparently it's a boon for periodontists: Gum disease has been found to be five times as prevalent among hookah smokers as among cigarette smokers, according to an online report in the July 2007 British Medical Journal.
But the actual science behind some of the statistics cited about hookah smoke is problematic, says Kamal T. Chaouachi, a Paris-based tobacco researcher who is widely published on the subject.
While not disputing the dangers of hookah smoke, Chaouachi said many statistics cited about hookah smoke are based on studies conducted using machine-produced smoke, which isn't consistent with the way hookahs are actually smoked. In addition, the studies vary in the types of tobacco tested, the temperature at which it's burned and the type of charcoal used to keep the tobacco lighted , all of which can affect results greatly. Consequently, there's a discrepancy in findings.
Burns, a contributor to the WHO advisory panel, is equally worried about the inconsistencies and overall lack of data on the effects of long-term hookah smoking.
"We know very little about the outcome of that behavior, whether people develop substantial levels of disease from use," he says. "We're quite concerned at this point in the social history" of the hookah.
Public-health experts worry that hookah smoking might lead to cigarette smoking. "One of the concerns the American Lung Association has about any kind of social smoking is that it's a possible gateway to cigarette smoking," Knepprath says.