The Environmental Protection Agency under President Donald Trump is aiming to undo or revise more than 30 major environmental regulations, many of them written or updated by the Biden administration. These include rules for cleaner vehicles, power plant emissions, and limits on tiny airborne particles known to harm human health.

The Associated Press set out to examine what might happen if all the rules were eliminated. The AP built on earlier work by the Environmental Protection Network, reviewing thousands of pages of regulatory impact analyses -- documents agencies must produce for major rules with economic effects.

The methods used to estimate the annual financial costs and benefits of each rule have been largely standard since Ronald Reagan's presidency. Each analysis must go through months of review across multiple agencies, said K. Sabeel Rahman, a Cornell law professor who was a top regulator under the Biden administration.

"These are hundreds of pages of technical documentation, extensively researched and footnoted, and then pressure-tested within the executive branch," Rahman said.

The AP also drew from studies published in the journals Science and Nature Communications and emissions estimates from the independent and nonpartisan Rhodium Group in order to calculate the possible annual death toll. The AP's work was reviewed by multiple outside experts. AP interviewed more than 50 scientists, officials, analysts and advocates for the story.

The estimate of global deaths includes estimates of heat deaths from added carbon emissions, using a peer-reviewed formula developed by Daniel Bressler, a former White House climate economist during the Biden administration. It estimates one person will die for every 10,217 tons (9,318 metric tons) of carbon dioxide added to the atmosphere.

The Rhodium Group estimates that the Trump administration's rollbacks would lead to 2.8 billion additional tons (2.6 billion metric tons) of carbon dioxide emissions by 2035 -- translating to, on average, more than 25,000 deaths each year.

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