As his 12-year run as mayor of New York City ends, Michael Bloomberg leaves behind a legacy of aggressive measures designed to improve the health of the city’s residents. His administration built bike lanes, plastered anti–soda ads on subways, funded produce sellers and undertook scores of other innovative—some say, heavy-handed—initiatives, many of which were widely imitated by other municipalities. "It's remarkable the number of things they've been able to do," says Ryan Demmer, assistant professor of epidemiology at Columbia University. Demmer and colleagues combed through government databases and found that Bloomberg-era public health measures numbered more than 100.

But did all those programs make New Yorkers measurably healthier? Now that the mayor’s final term is coming to a close, statisticians are starting to weigh in on his legacy. Their conclusion, from the past 12 years of data, could be summed up as “yes, but it’s complicated.”

Some key health trends clearly argue in Bloomberg's favor. Notably, from 2006 to 2010, life expectancy in the Big Apple rose by three years, outpacing the national average of 1.7 years.

Experts give some credit for those longer life spans to the mayor’s antismoking crusade, which they call an unqualified success. In 2003 Bloomberg increased cigarette taxes and banned workplace smoking. He extended the ban to public parks and beaches in 2011, throwing in free nicotine patches and hard-hitting ad campaigns along the way. These measures coincided with dramatic drops in tobacco use. From 2002 to 2009 adult smoking decreased by 27 percent in the city, including a historically unprecedented 11 percent drop between 2002 and 2003.

The data are equivocal, though, when it comes to kids. Although youth smoking declined in New York under Bloomberg, the city only matched the national trend. That, however, may simply reflect the wide adoption by other localities of Bloomberg's polices. "In 2002 only one state, California, had any smoking ban," Demmer says. "In 2011, 80 percent of people in the country were covered by smoking policies."

By reducing secondhand smoke, the bans also protected the health of nonsmokers. A New York State workplace ban, which began shortly after the city's measure, likely prevented around 3,800 yearly hospitalizations for heart attacks related to secondhand smoke, one study found (American Journal of Public Health, 2007).

Whereas life span and smoking have trended positively in New York, other public health indicators have gotten worse. Most troublingly, Gotham obesity and diabetes rates reflect the worsening national epidemics. Incidence rates of both conditions have doubled in the city since the '90s, and Bloomberg's responses to these problems constitute some high-profile policy failures.

A 2006 measure requiring restaurants to list calorie counts received wide public health support, but studies show that the policy has had little effect on calorie consumption. "There's definitely a percentage of people who see it and respond to it," says Brian Elbel, assistant professor of health policy at New York University Langone Medical Center, who published one such study, "but it's not enough to have an overall effect."

A state judge struck down a ban on sugary drinks larger than 16 ounces after it met with public opposition. Although 60 percent of New Yorkers supported the smoking ban when it passed, the same percentage opposed soda strictures. "With smoking, I get it," says Matt Friedlander, 32, a smoker who has worked in bars there since 1999. "Other people don't want it in their lungs. But if I want a 32-ounce Slurpee in the middle of August, I have the right to get it."

Perhaps because it only affected the ingredients businesses could use, not the final products consumers could choose to buy, Bloomberg's policy banning trans fats from restaurants met with less public opposition. Fully implemented in 2008, the mandate resulted in significantly healthier meals, researchers found, with trans and saturated fat content in restaurant French fries, for example, dropping 50 percent.

Aside from those well-known nutrition efforts, obesity has prompted a raft of disparate policies, like the nearly 500 "Green Carts" bringing fresh produce to underserved neighborhoods. The addition of hundreds of new bike lanes, along with a bicycle-sharing program, helped increase ridership by nearly 20,000 bikers per 12-hour count under Bloomberg's watch, says Jennifer Godzeno, planning director for Transportation Alternatives.

Children are a bright spot in the mayor’s health legacy. The rate of obesity in New York City children decreased by 5.5 percent from 2006 to 2011. The administration’s initiatives to improve safety along walking routes to schools, and other policies aimed at increasing activity levels among kids have probably helped.

The impact of City Hall’s health policies should show up more clearly over the next decade. "A lot of these other programs are not going to be a slam dunk like the smoking ban," Elbel says. "But they could be important cumulatively." In this respect, Bloomberg’s legacy may be in the hands of his successor, Mayor-elect Bill de Blasio—and the public health researchers sifting through the data.