The D.C. Council will vote Wednesday on a broad new proposal that would ban smoking within 25 feet of any city-owned park, community or recreation center, hiking trail or bus stop.

The ban, up for the first of two council votes, would curtail smoking on hundreds of city blocks and around what Metro officials say are 3,426 bus stops in the city.

Approved last week by the Committee on Transportation and the Environment, the proposed ban appears to have broad support among the council’s 13 members. If enacted, the District would join more than 300 cities that have banned smoking in parks, although few have included bus stops.

“It is unfortunate for any resident or visitor to be exposed to the dangerous effects of secondhand smoke, but it is even more unfortunate when we expose our children to this danger,” council member Mary M. Cheh (D-Ward 3), who chairs the committee, said in a statement that cited the health risk of secondhand smoke.

But the council chairman, Phil Mendelson (D), said Tuesday that he has “concerns” the council may be overreaching. “It’s very broadly construed, and we need to be careful where we don’t get into a situation where we make it unlawful to smoke in the District of Columbia,” Mendelson said. “Then we are just creating a new class of criminals.”

The bill, which has the backing of the administration of Mayor Vincent C. Gray (D), is one of dozens the council plans to act on Wednesday before going on a two-month summer recess. Council members are scheduled to vote on a controversial measure that would require large retailers to pay workers at least $12.50 an hour, on a proposal to allow undocumented immigrants to obtain driver’s licenses and IDs, and a plan to move the city’s 2014 mayoral primary from April to June.

The bill would establish a 25-foot, no-smoking buffer around 300 city parks and playgrounds as well as recreation centers and bus stops. The 25-foot buffer — where “no-smoking signs” would be required — would extend from bus stop signs or the property line for each District-run park or facility.

The proposed law would not apply to federal properties, such as the Mall or Dupont Circle. And it would exempt a homeowner or tenant who resides within a 25-foot buffer to use tobacco “within his or her residence,” according to the committee report.

But the measure would build upon a 2010 District law that permits private businesses and government offices to ban smoking within 25 feet of an establishment’s front door. That law supplemented the city’s 2006 indoor smoking ban.

“We know the impact of secondhand smoke, and we know the impact it has on children, the impact it has on seniors, and people with respiratory problems,” said council member Kenyan McDuffie (D-Ward 5), who voted for the measure in committee.

Mendelson said the legislation will be too hard to enforce, and added that he would speak with Cheh to seek changes in the bill.

But council member Jack Evans (D-Ward 2), who supports the bill, said he is confident that residents would adapt to the law, as they did when the city adopted its indoor smoking ban.

“If it’s a law, over time, people accede to the law,” Evans said.

Bronson Frick, associate director of Americans for Nonsmokers’ Rights, said the District’s proposed law “is in line with trends happening across the country” as more states and cities seek to curb smoking in public places.

“People with disability or seniors, waiting for the bus, why should they have to wheel away from the stop while someone else smokes?” Frick said, adding that the key to a successfully implemented law is “good signage.”

Yet, Columbia University researchers Ronald Bayer and Kathleen Bachynski published a study this week questioning whether smoking bans lessen the effects of secondhand smoke. Instead, they said outdoor bans are primarily used to “denormalize” smoking, the Los Angeles Times reported.

And Peter Hamm, national communications director for the Campaign for Tobacco-Free Kids, said the council should emphasize funding for tobacco-cessation programs before expanding its outdoor smoking restrictions.

“There are some places where outdoor secondhand smoke can be a nuisance and have an impact on people with asthma, like restaurant outdoor seating,” Hamm said. “But at a little bus shelter early in the morning, [a ban is] paying lip service to the concerns about health impacts of tobacco.”