For some workers in the city of Boston, a new ordinance passed by the City Council will mean better protection against extreme heat next summer.

That local legislation requires the city of Boston and its contractors to develop a heat illness prevention plan that would include providing employees with opportunities to access shade, water and rest as well as to receive training on heat-related illness and develop response plans in case of emergency.

If signed by Mayor Michelle Wu, it will go into effect six months after its passage.

The measure takes steps to make sure workers are safe amid a changing climate, said Madeleine Scammell, a professor of environmental health at Boston University and faculty member with the school’s Institute for Global Sustainability.

“People think they can handle the heat; they think, often, they’re not at risk of experiencing illness because of heat. The truth is, nobody is immune to the harmful effects of heat,” said Scammell, who is unaffiliated with the legislation and is leading a study on how heat impacts workers.

District 6 City Councilor Ben Weber, who filed the ordinance alongside District 5 Councilor Enrique Pepén and at-large Councilor Henry Santana, said it will make sure the city and the businesses it works with are treating employees right.

“If an employer isn’t able to figure out how to get water or some shade in place for workers, we don’t want them sort of doing business in Boston,” Weber said. “We want to find employers who can get the job done, but also do it in a way that’s safe for our workers.”

The ordinance comes as Boston moves toward the end of a record-breaking summer. A June heat wave saw the hottest day for that month in the city on record, with temperatures reaching 102° (the previous hottest June day was 100°).

The summer also saw the city declare three heat emergencies — two or more days where the heat index reaches 95° or higher. And the city this summer has had 19 days with temperatures reaching 90° or higher — the most since 2022, when there were 21.

According to the U.S. Environmental Protection Agency, multi-day heatwaves are expected to become more frequent and more severe across the country.

“The writing is on the wall: The climate is getting hotter sooner and longer,” Scammell said.

Those warming trends have been prevalent in Boston’s summers in recent years, and it was against that backdrop that the City Council pursued this ordinance.

“We have to take steps to mitigate the damage that’s going to be done by climate change in our region, and this is one way we can do that,” Weber said.

Heat illness, which includes things like heat exhaustion and dehydration, can occur when the body can’t properly adjust to high temperatures or humidity. Conditions like heat illness, if untreated, can escalate into heat stroke, which can include the potential for organ failure.

And heat illness can mean judgement and reaction time, which can pose a danger when working with heavy machinery, Scammell said.

While anyone can be vulnerable to heat illness, older residents and younger residents can be at particular risk.

The only employers covered by the ordinance are the city itself and its contractors and subcontractors. Under the new ordinance, having a heat illness prevention plan will be required when a company submits a bid to work with the city.

Weber said the legislation’s current scope will cover a lot of workers in the city, while not complicating operations for companies that do work across the state and would have to adjust their operations from city to city — there currently exist no statewide or national heat protections.

Weber also said he sees this ordinance as the beginning.

“This is a good place to start — I don’t think this is the end,” Weber said.

Scammell, too, said that more action beyond this ordinance should be undertaken; she worried many smaller businesses that may not be as likely to get city contracts also may be less prepared for extreme heat or have less of the internal organizational structure to implement heat illness prevention plans themselves.

“It’s the smaller employers; it’s the family-owned businesses that are not bidding for work in the city that we also need to think about,” Scammell said. “Right now, they’re still going to be very vulnerable come summer of 2026. They could equally benefit from the illness prevention plans.”

She said she’d like to see Boston, as well as other cities and towns across the state, work with smaller employers to help educate them on heat illness and prevention measures as a way to change the culture around the topic more broadly.

Specific actions employers might have to take under the heat illness protection plans aren’t outlined by the ordinance. Instead, it leaves it up to the city’s Office of Labor Compliance and Worker Protections to determine appropriate steps, as well the triggering threshold on the heat index and what settings qualify as “at risk” for causing heat illness.

But the city’s legislation lays out the broad strokes: ensuring access to water, rest and shade for employees.

“Those are not new concepts, but they have never been required,” Scammell said.

Leaving the specifics open for now is appropriate, Scammell said, given the wide variety of worksites that may be included under the ordinance. Weber gave examples including construction sites, police details and parking enforcement.

“It’s going to take a while for employers to think through what’s feasible and they have the time now — I mean, it’s not going to be until next summer [that these plans are needed],” Scammell said. “They have a good number of months to think it through and maybe some will be creative.”