Smoking is illegal is illegal at most public places in New York City, but hookah bars have been able to skirt some of these regulations because of allowances for non-tobacco-based smoking material — but a new study may change that sooner rather than later.

With the rising popularity of hookah smoking, especially in light of it being more difficult to smoke, hookah bars have become big hangout joins for young people, including teenagers who believe it’s safer than cigarettes. Hookah water pipes use shisha, which typically comes in many flavors and while it is tobacco-based, it is also made up of molasses and herbs.

This material seemed like a safer option, but the health and air quality in these bars appear quite similar to areas that expose people to heavy second-hand tobacco smoke, according to a UPI report.

Some hookah bars in New York have been shut down for smoking the tobacco-based shisha rather than the kind based on herbs and molasses.

The findings, published in the journal Tobacco Control, involved sampling the air during work shifts of 10 people who were employed at New York hookah bars. They then measured levels of carbon monoxide, nicotine, and other fine particulate matter. They also had their heart rate and blood pressure levels monitored.

What they found is that the environments were secondhand smoke danger zones, with substances found that were typical of areas that allowed indoor smoking.

These bars sold the tobacco-based shisha, and authorities believe such bars are widespread in the New York area despite operating illegally.