That study failed to mention that normal cigarettes contain between 10 and 100 times the amount of diacetyl found in e juice. Cigarette use could not actually be linked to popcorn lung, though. The diacetyl problem has been known in vaping communities for a while. Some are fine with just doing "less harm" as far as anyone can tell, others make sure they only use juice / aromas which are declared diacetyl free by manufacturers (many of whom have been phasing out diacetyl containing products since about 2010). I'm still slightly worried by all this, because we do indeed not have the data for the effects of 20 or 30 years of exposure. Vaping has replaced smoking completely for me and after about 2 years or so, the immediate effects on my respiratory system have been highly beneficial. Anyone who just discards potential long-term effects is imho just falling victim to wishful thinking, though.