I've been smoking pot since age 18 and I am 56 now. Through decades of pot smoking my lung capacity (which once was Asthmatic since I was born with Chronic Bronchial Asthma) was pretty much ruined. Despite no signs of Asthma, which I lost in teenage years through intensive swimming, I had extremely limited lung capacity. I switched to vaping in 2008. I have smoked also since for six months or even a year at a time but predominately vaping since my lungs clear and I get full lung capacity aqain whilst doing so. Indeed I'd prefer smoking mostly due to the ritual nature but vapes are my salvation when my lungs can no longer handle the daily imposition of smoke and byproducts of pyrolisation. I happen also to be an underground chemist. albeit 'retired' and my police record reflects this. I have seen how much oil and hash is produced by use of solvents and many of the solvents are not easily able to be removed adequately from the final product absent some knowledge and the right equipment, so much of the underground product is tainted. The use of tech grade solvents alone can introduce cynanide etc into the batch. Very few underground labs use anything but tech grade. Lab grade is simply too hot to touch. Tech grade or less is all that they have available unless they have the knowledge to purify it. Which very few have.
The problem I see with the currently newsworthy vaping related illnesses is that the context is missing and also there isn't even any way at this time of testing ANYTHING alongside a control group of users who use only natural products. I use exclusively home grown and organically produced cannabis in my vapes. If I extract anything it is done with the correct solvents and laboratory apparatus to at least produce a minimal standard of purity. ie: low temp and minimally poisonous solvents, vacuum distillation etc. I have not only got no health problems from a lifetime of such practices, I am uncommonly healthy and resistant to even chronic illness as time has proven.
If you use commercial products, you risk being poisoned. It is that simple. This is one of the two reasons that traditional users of cannabis since the sixties have resisted "LEGALISATION" preferring simple decriminalisation instead. We'd rather get fined for smoking a joint than hand over not only the profits but the CONTROL of our preferred intoxicant to $$$ corporations.