A $43,000 secure phone booth and a 24-hour security detail - Pruitt has taken extraordinary measures to protect himself from potential enemies

Pruitt is the first EPA chief to have round-the-clock security.

Last year, as the agency planned to hire a dozen more agents to protect Pruitt, the EPA's inspector general announced he would look into whether the excess security was a necessity or a waste of taxpayer money, CNN reported at the time.

But Pruitt's office argues the security is needed.

"We have at least four times — four to five times the number of threats against Mr. Pruitt than we had against Ms. McCarthy," assistant inspector general Patrick Sullivan told CNN, referring to Gina McCarthy, who served as the EPA administrator during former President Barack Obama's second term.

Last March, the EPA paid $3,000 to a contractor to do a sweep of Pruitt's office to make sure there weren't any covert or illegal surveillance devices.

Pruitt's spokesman, Jahan Wilcox, defended the sweep by pointing to the "unprecedented amount of threats against [Pruitt]," according to The Hill.

Wilcox also said former Obama-era EPA chief Lisa Jackson had a similar security sweep while she was in office, but a former EPA employee who worked with Jackson told The Hill that she never personally requested it.

Pruitt has also been coy about announcing his official government trips.

In an interview with The Washington Post, EPA spokeswoman Liz Bowman said the agency doesn't release Pruitt's schedule ahead of time "due to security concerns."

When Business Insider's Rebecca Harrington visited Earth Day Texas in April 2017, event organizers didn't confirm Pruitt was coming to speak until two hours before he was rumored to appear.

Pruitt has also been criticized for taking expensive trips abroad. Last year, for example, a four-day trip to Morocco cost taxpayers roughly $40,000.

In December, Democratic Sen. Tom Carper sent a letter to the EPA's inspector general requesting an audit of Pruitt's travels to "determine whether his activities during each trip are in line with EPA's mission to 'protect human health and the environment.'"

In December, The New York Times published a report detailing the EPA's decision to hire Definers Public Affairs, a Virginia-based consulting firm, to monitor media coverage of the agency.

But some EPA employees complained that the firm was actually being used to track the communications of those critical of Pruitt and President Donald Trump.

For example, one employee based in Philadelphia said his emails were targeted by a FOIA request, initiated by Definers Public Affairs, one week after he took part in a rally against proposed EPA budget cuts.

"What they are doing is trying to intimidate and bully us into silence," Gary Morton, the employee, told The Times.

The EPA said the firm was hired to do the agency's press clips and denied any wrongdoing.

Pruitt's frequent use of first-class airfare has also come under scrutiny.

In an interview with the New Hampshire Union Leader newspaper last month, Pruitt justified paying more to fly first-class, even for trips that are often not entirely relevant to his work as a Cabinet official.

"We've had some incidents on travel dating back to when I first started serving in the March-April timeframe," Pruitt said. "We live in a very toxic environment politically, particularly around issues of the environment."

He also said he is not directly involved in security decisions.

In one example that has come under the microscope, Pruitt spent more than $1,600 on a first-class plane ticket from Washington to New York in June 2017 in order to make two brief television appearances to promote the president's decision to withdraw from the Paris climate agreement.

The Washington Post reported that his ticket cost more than six times what two of his aides paid to sit in coach.