Washington(CNN) EPA Administrator Scott Pruitt's travel expenditures are being looked at by House Oversight Committee Chairman Trey Gowdy, according to a letter from the committee dated Thursday.
The committee chairman asks Pruitt to provide various documents related to his travels, following reports that Pruitt has traveled first class on multiple business-related trips.
"Clearly, federal regulations prohibit a blanket waiver to fly first class except to accommodate disabilities or special needs. Instead, a waiver for each flight is required in order to fly first class or business class when traveling on official government business," reads the letter from Gowdy, a South Carolina Republican.
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The EPA inspector general announced last August that it was investigating Pruitt's travel habits, including multiple trips he took to Oklahoma, where he previously served as the state attorney general.
Pruitt told The New Hampshire Union Leader last week that his travel on military jets or in first class was due to security concerns.
"We live in a very toxic environment politically, particularly around issues of the environment," Pruitt told the newspaper. "We've reached the point where there's not much civility in the marketplace and it's created, you know, it's created some issues and the (security) detail, the level of protection is determined by the level of threat."
CNN also reported on documents that revealed how the EPA had justified paying for several charter flights for Pruitt.
In one case, the documents show that air travel was approved by EPA's acting general counsel, citing official business and that the destination was "not accessible through commercial means."
CNN's reporting showed that the trip to Guymon from Tulsa, Oklahoma, was about a five-hour drive, and from Guymon to Oklahoma City about a four-and-a-half hour drive.
According to the documents, "the time constraints on the Administrator's schedule did not allow the Administrator to travel by ground transportation."