He proposed Wednesday to tweak the building code to promote using stairs, including by requiring new buildings and major renovations to have a stairway open for non-emergency use and by allowing them to keep stairwell doors open most of the time.
They're part of a push to promote "active design," or shaping the built environment to encourage physical activity. Bloomberg is styling it as the latest focus in his much-touted - and sometimes mocked - fight to curb obesity.
"New York City has been a leader when it comes to promoting healthier eating, and now we're leading when it comes to encouraging physical activity as well," Bloomberg said.
Active design has gained cachet in recent years among architects and public health experts, who see it as a low-key but effective way to build more exercise into lives that cars, elevators and other factors have made more sedentary over the decades. Less than half of American adults met aerobic exercise guidelines in 2011, according to the Centers for Disease Control.
New Yorkers are on the move more than many Americans, because lots of city residents depend on public transportation, walking and bicycles to get around. Still, only 30 percent of New Yorkers get recommended amounts of physical activity, city Health Commissioner Dr. Thomas Farley said.
Active design can entail making sidewalks more inviting, biking more convenient, and the like. And especially in a vertical city, "stair-climbing is an important, valuable, and under-recognized form of physical activity," Farley said. A 150-pound person burns about 10 calories a minute walking up stairs, compared to 1.5 calories riding an elevator, according to the CDC.
But stairwells are often windowless and uninviting, and sometimes locked from the inside, officials noted.
Bloomberg wants to smooth the way for devices that keep stairwell doors open, except in emergencies. Now, stairwell doors generally must close by default, to keep smoke and flames from spreading in the event of a fire.
Under his proposal, new buildings could use "hold-open" devices on three consecutive floors on one stairwell, without having to seek special permission. The devices automatically shut the doors if a fire alarm goes off.
The mayor also wants to require new buildings and major renovations to include at least one continuous stairway open for non-emergency use, with fire-safe windows in the doors. A continuous stairway has flights right above each other, rather than stairs in one area on some floors and elsewhere on others.
Those proposals would need City Council approval, and some exemptions could be made for security.
The head of a major New York construction industry group said he wanted to know more about how the concepts would be put into practice, but he applauded the overall idea.
"Designing for health is a very worthwhile thing," said Richard Anderson, the president of the New York Building Congress.
The Fire Department didn't immediately respond to a request for comment.
Bloomberg also recently signed an order requiring city agencies to look for opportunities to incorporate active design principles when constructing or heavily renovating city buildings or streets. The city put out active design guidelines, as suggestions, in 2010.
During his nearly 12 years in office, Bloomberg has successfully led charges to start a bike-sharing program, ban smoking in bars and restaurants, make chain restaurants post calorie counts on their menus and ban artificial trans fats in restaurants, among other health initiatives. He also has tried to limit the size of sugary drinks; a court struck that down, but the city has appealed.
While some see his health crusades as government hectoring, health officials praise them as often groundbreaking, and he frequently notes that life expectancy has risen at nearly twice the national rate since he took office in 2002.
As for whether the 71-year-old billionaire chooses to climb stairs himself, he said he does it all the time: His Upper East Side townhouse has five floors.
It also has an elevator, but "stairs are much faster and more convenient," he said.