Environmental Protection Agency (EPA) head Scott Pruitt has spent much of his first year in the role taking first-class or business-class flights, totaling thousands of dollars and often at the expense of taxpayers, The Washington Post reported Sunday.

EPA records show Pruitt typically flies first or business class for unspecified security reasons, according to the report. He has also reportedly used military jets to travel to and from events.

The newspaper found one stretch in June in which Pruitt and his top aides racked up at least $90,000 worth of taxpayer-funded travel.

Pruitt's aides generally fly coach when traveling to and from trips to speak at conferences and political events, the newspaper reported, but Pruitt flies first or business class, a break in tradition from past administrators.

EPA spokeswoman Liz Bowman told the Post that all of Pruitt's travel expenses have been approved by federal ethics officials.

Federal regulations call for government travelers to "consider the least expensive class of travel that meets their needs," though agencies can use first-class for security or medical reasons.

The Washington Post found Pruitt frequently used the security exception to justify traveling first-class.

Health and Human Services (HHS) Secretary Tom Price resigned in September following uproar over his use of private jets for official business. His resignation followed Politico reports that his use of military flights and private jets cost more than $1 million.

Prior to his appointment in the Trump administration, Pruitt served as the attorney general in Oklahoma. He has drawn criticism from environmental advocates for questioning climate change.

Last week, Pruitt suggested it's unclear if global warming is harmful to humans.

Under his leadership, the EPA has rolled back Obama-era environmental policies and withdrawn from the Paris climate accord, which is aimed at fighting global warming.