A partial smoking ban instituted by the city of Louisville, Ky., has not done much to make the air in bars, restaurants, and entertainment venues cleaner, the Louisville Courier-Journal reported June 20.

University of Kentucky researchers measured air quality in places affected by the ban and found little change compared to readings taken before the ban took effect last November.

The study found that while air quality improved at businesses that went completely smoke-free, those that chose to establish smoking rooms under the law failed to improve air quality. The study found that in restaurants that set up smoking rooms, air quality was as bad outside the rooms as inside.

"In places like Louisville, there are a lot of workers and patrons who are not protected," said lead researcher Ellen Hahn. Hospitality-industry officials said that the findings were unsurprising and that health advocates had not proven that the air is unhealthy. But critics of the Kentucky law said the research showed that the measure was too weak.

"[The law] just has too many exemptions," said Robert Powell, chair of the Jefferson County Smoke-Free Coalition. For example, businesses can allow indoor smoking if they equip a room with a ventilation system, and restaurants can qualify for an exemption if they can show that they don't sell much alcohol and have a high amount of carryout sales or patio dining.