An expert says Kiwis vaping nicotine products can breath a sigh of relief.

The number of vape-related deaths in the United States has risen to 17.

But Massey University's Dr Penny Truman says most of the deaths are linked to vaping cannabis - unlike the nicotine and water-based products here.

She says cannabis is oil-based which means higher temperatures and more breakdown products.

And she says the problem will only worsen as cannabis becomes legal in more states.