WASHINGTON — Smokers may be one minority in Congress with even fewer rights than newly demoted Republicans. Now, they’re losing one of their last, cherished prerogatives — a smoke break in the ornate Speaker’s Lobby just off the House floor.

The new House speaker, Rep. Nancy Pelosi, a Democrat of California, announced a ban yesterday, effective immediately.

“The days of smoke-filled rooms in the United States Capitol are over,” Ms. Pelosi said. “Medical science has unquestionably established the dangerous effects of secondhand smoke, including an increased risk of cancer and respiratory diseases. I am a firm believer that Congress should lead by example.”

Lawmakers will still be free to light up in their own offices. But they’ll no longer be able to mingle in the Speaker’s Lobby in a haze of cigarette smoke during House votes, as they did just Tuesday night while passing anti-terror legislation.

The House minority leader, Rep. John Boehner, a Republican of Ohio, who is a heavy smoker and often at the center of a group of smokers puffing away in a corner of the lobby, had little to say yesterday about Ms. Pelosi’s move. Questioned at a news conference, Mr. Boehner described it as “fine,” without elaborating.

Smoking is banned in most federal buildings, and the District of Columbia recently barred it in public areas, as has Ms. Pelosi’s home district of San Francisco and a number of other cities.

So congressional smokers will be forced outside — onto the balcony off the Speaker’s Lobby, perhaps.

“That’s how life is now. They’re banning smoking everywhere,” Rep. Devin Nunes, a Republican of California and an occasional smoker, said.

The scent of Rep. David Dreier’s cigars has regularly filled the third floor of the Capitol, especially during visits from Governor Schwarzenegger, but Mr. Dreier, a Republican of California, took the decision in stride.

“I like to have an occasional cigar in my office,” Mr. Dreier said, but “she’s the speaker of the House, she can make these kinds of decisions. … No one wants to encourage smoking.”

The news hadn’t filtered to everyone yesterday. There were still ash trays in the Speaker’s Lobby, and around noon a House official sank into an armchair and lit a cigarette. Informed about the hours-old ban he made his way to the balcony.

“It just finally gets cold, and now they tell us you can’t,” he grumbled.

Capitol Hill smokers have been seeing their habitat shrink for more than a decade. In 1993, the House speaker, Rep. Tom Foley, banned smoking in hallways and other public areas. Last year, it was banned within 25 feet of the entrances to House office buildings.

Reminders of the days when tobacco was king remain throughout the Capitol.

Tobacco was a leading export of the early colonies and a mainstay of the American economy well into the 20th century, a fact recognized in the tobacco-leaf motifs carved into the top of many of Capitol’s columns.

Cigarettes can be purchased in a House store, and are sold by the carton at a sundry shop underneath the Hart and Dirksen Senate office buildings where the phone is answered, “Hart tobacco shop.”