(FILES) In this file photo taken on January 22, 2018 shows Jeremy Wong blows vapor from an e-cigarette at The Vaping Buddha on January 23, 2018 in South San Francisco, California.  US health officials are investigating the cases of dozens of people, mainly teens, who were hospitalized with severe lung injuries in recent weeks after vaping, though the precise cause of their illnesses remains a mystery. / AFP / GETTY IMAGES NORTH AMERICA / Justin SULLIVAN
The research reported significant changes in the blood flow within the femoral artery in the leg. Getty

A few puffs on a nicotine-free e-cigarette impedes blood vessel function, study finds

The National