This is anecdotal, so keep that in mind when making your decision. I have had 2 friends develop lung issues from smoking the oil in vape pens. Several years ago one of my friends switched to flower only and he has since recovered. My other friend who still smokes the oil has developed worse lung problems. I think that our lungs have evolved to be able to clear particulates out of them with relative ease. Oil, however, has never been something that we breathe in. The oil vapor enters the lungs and then reliquifies. This liquid is thick amd sticky and goes into the fine tube of your lungs. The normal process your lungs use to clear debris is not very effective at clearing this sticky oil and can take much longer.