EPA Administrator Pruitt. Aaron P. Bernstein/Getty Images

The Environmental Protection Agency’s internal inspector general said in an internal memo that he is expanding his investigation into agency head Scott Pruitt’s air travel. A probe last year had found Pruitt's "non-commercial" flights between June and August cost taxpayers more than $58,000.

Why it matters: Pruitt and other Trump administration officials have been under scrutiny for flying charter, military or private jets paid for by taxpayers. According to the memo, published online on Wednesday, the decision to expand the scope of the probe through the end of 2017 came in response to “additional congressional requests.”

Go deeper: The Trump officials caught splurging on luxury travel

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22 mins ago - Health

More Republicans say they're wearing masks

Data: Axios/Ipsos poll; Chart: Andrew Witherspoon/Axios

Nearly two-thirds of Americans — and a noticeably increasing number of Republicans — say they’re wearing a face mask whenever they leave the house, according to the latest installment of the Axios-Ipsos Coronavirus Index.

Why it matters: A weakening partisan divide over masks, and a broad-based increase in the number of people wearing them, would be a welcome development as most of the country tries to beat back a rapidly growing outbreak.

Buildings are getting tested for coronavirus, too

Illustration: Eniola Odetunde/Axios

Testing buildings — not just people — could be an important way to stop the spread of the coronavirus.

Why it matters: People won't feel safe returning to schools, offices, bars and restaurants unless they can be assured they won't be infected by coronavirus particles lingering in the air — or being pumped through the buildings' air ducts. One day, even office furniture lined with plants could be used to clean air in cubicles.

37 mins ago - Science

The summer of Mars

Illustration: Aïda Amer/Axios

Three missions from three different nations are heading to Mars in the next month — including one from the United Arab Emirates, a newer player in planetary exploration that is expected to launch its first spacecraft to the Red Planet this evening.

Why it matters: More nations are now going to space as the costs of launch and development are driven down. Mars is a step farther that is reserved for those with the most ability and resources — missions to the planet are a mark of scientific and technical prowess on the global stage.