Cooling centers were open but few came. Are they the best way to deal with scorchers?

Building manager Bill Miller at the Nazzaro Community Center cooling center on Tuesday.Suzanne Kreiter/Globe Staff

It was a blistering hot day, the third in a late spring heat wave. But some of the community cooling centers the city offers its residents were all but empty.

A community cooling center in the North End had no takers around noon Monday, as the thermometer hovered around 93 degrees. In Roxbury, another center had just two patrons enjoying its air-conditioned rooms.

As the number of 90-degree days has steadily climbed in the area, the sparse use of the city-funded cooling centers illustrated the challenges for cities trying to help people withstand the heat — a serious health threat, particularly for the elderly.

And with climate change promising an uptick in sweltering days, city governments around the nation are looking for new and more practical ways to keep people cool, including planting trees in hot spots and passing out free air conditioners to those who can’t afford them.

Heat is not just uncomfortable. It’s also a “major problem for health,” according to Dr. Aaron Bernstein, interim director of the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health.

“There are more people who die in the United States from heat exposure than from all other natural disasters,” Bernstein said. A study by the Centers for Disease Control and Prevention in 2020 estimated about 702 annual heat-related deaths nationwide.

And the effects of high temperatures “fall most heavily on poor, disadvantaged people of color and people who have health problems,” he said.

Mary Louise Sowers — the program manager at Boston Centers for Youth & Families on Vine Street in Roxbury, which hosts a cooling center — blamed a lack of transportation as one reason for the sparse turnout there.

“Usually people are not going to come out if they have to walk somewhere to get to the center,” Sowers said. “If there was transportation for the elderly, I think we’d probably get more.”

Cambridge hasn’t offered cooling centers since 2014 because they were going unused, said spokesman Lee Gianetti. On Monday, Cambridge instead advised residents to find a local waterplay area to stay cool. The Cambridge Council on Aging also works to directly reach out to senior citizens who may be at risk from the heat and help them in their homes, according to Gianetti.

Cambridge Vice Mayor Alanna Mallon said numerous constituents have contacted her this week about the lack of a cooling center, which she in part attributed to the pandemic.

“It is really frustrating that the city does not have a citywide cooling center right now, given that our senior centers are closed, our public libraries are closed, our youth centers are closed,” Mallon said. “There’s just no place to gather right now and be able to get away from this heat.”

On Monday, Mallon proposed an order to reopen public libraries in Cambridge by June 15, in part to serve as cooling centers for future heat emergencies.

“As we are in this escalating climate emergency, there are going to be many more days over 100 degrees,” she said in an interview earlier that day. “We need to ensure that our public buildings are actually open and available for residents.”

But as the number of hot days increases, some places are looking for more effective solutions.

Last summer, while the pandemic raged, New York City proposed paying the utility bills for 450,000 vulnerable New Yorkers so they could afford to run their air conditioners. New York City also piloted a program in 2019 to provide free air conditioners to some of its residents in public housing.

Quinton Zondervan, a member of the Cambridge City Council, said a similar measure was discussed — and subsequently, shot down — in Cambridge, once in 2013 and again in 2017, because an amendment to the state constitution prevents city governments from providing direct aid to its residents.

Nonprofits don’t face the same red tape. Communities Responding to Extreme Weather — a local organization focused on climate resilience — bought 107 energy-efficient air conditioners last summer and gave them to low-income residents in Brockton. They plan to run the initiative again this summer.

Discussions about how best to bring relief from the heat are important, said Harvard’s Bernstein, because it is a health concern “from before birth to old age. It matters to every organ in our bodies — we see problems with heart diseases, lung diseases, kidney diseases, infections, brain diseases.”

For now, cooling centers remain the primary relief that is offered in the area, despite the fact that public health experts lack data on the centers’ effectiveness, he said.

“What is clear is people don’t use them nearly commensurate to the need,” Bernstein said. “That’s not entirely surprising, especially when you’re talking about people who are older, going to a place they may have never been before, with no one they know and potentially nothing they want to do.”

Nonetheless, Bernstein contended cooling centers are “important.”

“We know that access to air conditioning is a major factor in whether people will live or die in heat waves, and people may not have access to it for a number of reasons,” he said. “I think facilitating access to those as best we can is critical.”