Leighton Meester’s building is a smoke-free zone.

The Gossip Girl beauty has left her neighbors in a huff after she banished cigars, cigarettes, and other forms of cancer sticks from all apartments sharing a floor with her posh NYC pad. Leighton has asked neighbors to refrain from lighting up inside their homes because she “develops a sore throat if she’s exposed” to smoke.

“She asked everyone not to smoke because the smell comes under her door,” a Leighton spy tells Star.

Ironically, the young star’s boyfriend, actor Sebastian Stan, and co-star Ed Westwick are both heavy smokers.

“Everyone thinks she’s being a diva.”