Yes some ejucie may have some Diacetyl within it and that is not "safe" the article and many other trying to give this terrible impression on vaping miss many things.
First, this article give no exact juice brands so where's the evidence there?
(would love to see it actually)
Second, it does not give an amount of Diacetyl within each juice. From what I've read is mostly extremely small to "harmless" amounts.
Third, vaping is primarily a alternative to smoking, smoking has somewhere around 10 times the amount of Diacetyl within a cigarette and this article fails to even compare the two. Not even thinking about the other thousands of chemicals within a cigarette.
While vaping is not "perfect" it is a much safer alternative. It may be slightly harmful yes but there are several other things humans do that can be just as if not more harmful.
Don't let fear mongering articles like these sway you.
I would love to see some real studies with real name brand juice and devices so we can see exactly what goes on.
But watch for things like "government funded" (I don't believe it was this exact article but another reporting the same study states this) government funded mostly means big tabbaco companies. Who want your tabbaco money.