ATLANTA: Despite the fears of many restaurant owners, smokefree laws are good for business, according to a study of four Texas cities with some of the strictest rules in the state about lighting up while eating out.

The study is the largest so far in Texas trying to examine whether tough smoking ordinances drive customers away. Researchers from the Texas Department of Health used tax data to track sales in Plano, Arlington, Wichita Falls and Austin before and after smoking rules went into effect. Total restaurant sales generally continued to climb in all four cities.

"Clean indoor air ordinances do not adversely affect restaurant sales," said Dr. Phil Huang, chief of the Health Department's Bureau of Chronic Disease and Tobacco Prevention. "It's an unfounded fear." His study was presented Wednesday in Atlanta during a conference hosted by the U.S. Centers for Disease Control and Prevention.

The study comes during a time when the Dallas City Council may consider strengthening its smoking policy. Currently, Dallas restaurants must have clearly designated smoking areas, and where possible, separate ventilation. Bars, bar areas and extremely small restaurants are exempt.

In other cities, such as Plano, smoking is banned unless the smoking section has separate ventilation. Council member Lois Finkelman has asked the city's Environmental Health Commission to consider revising Dallas' ordinance.

Previous attempts to further restrict smoking in Dallas have failed, largely out of concern that such laws will put restaurants out of business. Restaurant owners generally oppose strict smoking rules not because they want people to smoke, Ms. Evers said, but because they need flexibility to run their business. "We want restaurants to be able to meet the demands of their market."

Public health officials, acknowledging these concerns, have tried to gather data to determine whether this occurs. A study from researchers at the University of California, San Francisco found that restaurant business in 15 towns that banned smoking did not differ from sales in 15 other towns with similar economic profiles that allowed smoking. The only previous study in Texas examined restaurant business in West Lake Hills, a small suburb of Austin.

Dr. Jim Hayslett, who conducted the new study with Dr. Huang, said they chose four cities that had enacted some of the toughest restrictions. Also, to account for economic ups and downs, they examined both total restaurant sales and restaurant business as a percentage of total retail sales in each city.

They found, for example, that restaurants in Plano accounted for about 11 percent of the city's retail sales from 1988 to 2000, and the percentage was virtually unchanged after smoking policies were enacted during the mid-1990s. Restaurant sales in Arlington hovered around 12 to 15 percent during those 12 years.

Dr. Huang said he believes that people who smoke continue to eat out even when they can't puff at the table. Movies last longer than a dinner, he said, and "smokers aren't saying, 'I'm excluded from going to movies.' "