LAS VEGAS — It was Final Four weekend, and James Riviello was in a mood to make some serious money. The professional gambler sat in a puffy tan leather chair inside the mammoth Westgate Casino sports book, a realm the size of a Costco warehouse, with eight super screens showing his favorite sport in colorful high-definition.

Here in the place known as Sin City, where vice normally calls the shots, there was something refreshing about the scene. You could almost call it healthy.

Nobody was smoking.

Just weeks before, the Westgate had banned cigarettes and their acrid aroma inside one of the city’s largest sports books. Gone were the chain-smokers who flicked their lighters every few minutes, cigarettes dangling from their lips.

For Riviello, the resulting thrill was like raking in his winnings. “It’s just so aggravating when someone sits there and blows smoke in your face,” said the 29-year-old Pennsylvania native.

In a city that all but encourages bad behavior, casino bosses here flaunt their gaming floors as the last bastion of the guiltless cigarette.

But Westgate’s move suggests the cultural shift toward smoke-free cities and public spaces may finally clear the air of some of the most celebrated smoke-filled rooms: Vegas casinos.

Jay Kornegay, Westgate’s Las Vegas vice president of race and sports operations, thinks the day is coming. “We’ve already gotten calls from some other operations in town,” he said. “People are surprised we haven’t gotten more pushback.”

In recent years, other Las Vegas sports books have banned smoking. Casinos offer nonsmoking gaming areas with special ventilation units, and most poker rooms are now smoke-free. But a stubborn resistance remains among casino bosses here against going totally smokeless.

In 1999, Nevada was the smokiest state in the nation, with nearly one-third of residents claiming cigarette habits. By 2014, that number had dropped in half. That followed a 2006 voter initiative in Nevada that banned public smoking, including lighting up while playing slots in restaurants, stores and gas stations.

But, as usual, the casinos got a pass.

“They are very influential,” said Maria Azzarelli, tobacco control program coordinator for the Southern Nevada Health District.

The city has even bucked an anti-smoking trend within the nation’s gaming industry. Of the 23 states with commercial casinos, 18 outlaw smoking. But not Las Vegas.

“We’re different,” said Kornegay. “Las Vegas is proud of its reputation as the nation’s adult playground.”

Then there’s the money factor: Studies suggest that smoking bans have historically led to steep declines in gaming revenue.

A 2014 report by Deutsche Bank suggested that a ban in Nevada could mean a 7.5 percent decline in gaming during its first year. Delaware’s gaming market fell 11.3 percent following a smoking ban in 2002. Illinois casinos reeled from a 20.9 percent revenue plunge after smoking was banned statewide in 2007, according to the report.

“Nevada’s gaming industry has witnessed the results in other states,” said Andrew Zarnett, a Deutsche Bank gaming analyst. “Operators and other stakeholders there, including the people who collect the taxes, have decided they’re not willing to take that decline in revenue.”

Casino bosses might also think that the experience of smoking somehow fuels more gambling. An internal 2003 report for the Australian gambling company Tattersalls claimed that “smoking is a powerful re-inforcement for the trance-inducing rituals associated with gambling.”