Firefighters assist a resident during a heat wave in Phoenix, Arizona, U.S., on July 20. Caitlin O’Hara/Bloomberg

President Biden said extreme heat is costing the U.S. $100 billion a year and linked it directly to climate change as he detailed steps his administration is taking to protect Americans from record-high temperatures.

“We want the American people to know, help is here, and we’re going to make it available to anyone who needs it,” Biden said Thursday at the White House, where he was briefed on the extreme weather.

“The No. 1 weather-related killer is heat,” said Biden, who warned it was hitting the most vulnerable Americans hardest. “Seniors, people experiencing homelessness who have nowhere to turn, and disadvantaged communities are least able to recover from climate disasters. And it’s threatening farms, fisheries, forests.”

Biden said he asked the Labor Department to issue a hazard alert, reaffirming that workers have heat-related protections under federal law, and warned states that aren’t protecting workers.

“We should be protecting workers from hazardous conditions and we will, and those states where they do not, I’m going to be calling them out where they refuse to protect these workers,” Biden said.

“For the farmworkers who have to harvest crops in the dead of night to avoid the high temperatures, or farmers who risked losing everything they planted for the year, or their construction workers who literally risked their lives working all day in the blazing heat, and in some places don’t even have the right to take a water break. That’s outrageous,” he added.

Under the alert, the agency will ramp up enforcement of heat-safety violations and increase inspections in high-risk industries such as construction and agriculture.

Heat waves have plagued the U.S. all summer. Today, some 170 million Americans are under excessive heat warnings and advisories, with New York City and the Northeast in for their hottest day of the year. Thursday’s high in New York will be in the mid-to-upper 90s, and humidity temperatures will feel closer to 106F (41C), the National Weather Service said.

The temperatures threaten to overwhelm power grids and slow transportation, particularly for air travel and railroads.

The U.S. has also been suffering from the effects of unprecedented wildfires in Canada, which have repeatedly blanketed east coast and Midwestern cities with toxic smoke and led to air quality alerts in multiple states.

Biden urged Americans to listen to advice from state and local officials, take advantage of cooling centers and places with air conditioning such as malls, community centers, and movie theaters, and check on neighbors and loved ones during the heat wave.

Biden at Thursday’s event heard from Mayors Kate Gallego of Phoenix, Ariz.; and Ron Nirenberg of San Antonio, Tex., on how extreme temperatures are affecting their communities.

The heat in Phoenix has shattered records this month, with the city experiencing temperatures of at least 110F every day since June 30. Even before this summer, extreme heat has been an emergency in Phoenix and the surrounding Maricopa County, contributing to hundreds of deaths each year and prompting local emergency doctors to innovate how they are treating people sick from the heat.

“I don’t think anybody can deny the impact of climate change anymore,” Biden said. “Even those who deny we’re in the midst of a climate crisis can’t deny the impact of extreme heat.”

Last year, the U.S. enacted the Inflation Reduction Act, the nation’s biggest climate law, pouring billions of dollars into efforts to respond to the climate crisis and boost the nation’s reliance on clean energy. The National Oceanic and Atmospheric Administration is investing up to $7 million from that law to improve weather predictions.

The Interior Department is also investing $152 million from the bipartisan infrastructure law to bring clean drinking water to communities across the West. The investments will increase water storage capacity and lay pipelines to deliver drinking water to communities most impacted by drought.

The Forest Service will award more than $1 billion in grants to help cities and towns plant trees that repel heat and provide more green space, Biden said.

Some progressive lawmakers and activists have called on the president to declare a climate emergency.

An emergency declaration would unlock sweeping executive powers, including blocking crude oil exports and placing other limits on fossil fuels. Biden considered the move last summer but ultimately decided against it.

Bloomberg’s Zahra Hirji, Brian K. Sullivan, and Hadriana Lowenkron contributed to this report.