The delivery giant UPS has reached an agreement with the Teamsters union to install air conditioning systems in its iconic brown delivery trucks.

The tentative deal comes as the two parties continue to negotiate the terms of a new contract for more than 340,000 unionized employees and after reports of UPS workers facing extreme heat in their vehicles while on the job.

"We have reached an agreement on heat safety with the Teamsters, which includes new measures that build on important actions rolled out to UPS employees in the spring, including new cooling gear and enhanced training," the company said in a statement.

Air conditioning systems will be included in all of the company's small package delivery vehicles purchased after Jan. 1, 2024.

It will be the first time UPS will be required to equip the company's recognizable "package car" vehicles — which make up about 95% of its delivery fleet — with air conditioning, the union said.

UPS said it would send the new vehicles to the hottest parts of the U.S. first when possible.

Under the agreement, UPS will ensure all current package cars have a cab fan within 30 days of the new contract being ratified; the company will also install heat shields, which reduce truck floor temperatures, and air induction systems to increase airflow in the cargo areas.

"Air conditioning is coming to UPS, and Teamster members in these vehicles will get the relief and protection they've been fighting for," Teamsters General President Sean M. O'Brien said in a statement. "The union's entire national committee and our rank-and-filers should be commended for staying in this fight and making their priorities known to this company."

Delivery drivers will increasingly face the ill effects of climate change, which among other things is making heatwaves both hotter and longer-lasting.

UPS, which delivered an average of 24 million packages per day last year, has faced criticism from labor leaders, workers and their families for not doing enough to protect drivers from extreme heat on their routes. Some drivers have even taken to sharing the scorching heat readings in their trucks.

More than 100 UPS workers were treated for heat-related illnesses in the span of four years, according to NBC News, and a 24-year-old UPS driver in California died last summer from what his family suspected was dehydration or heat stroke.

These days, nearly ever American car is equipped with air conditioning, according to the automobile group AAA.

Tuesday's agreement comes as the Teamsters weigh a strike vote that could allow the union to call a temporary work stoppage if it is unable to reach a contract deal with UPS. The current contract expires July 31.