You keep asking about NIOSH studies but then post a link to sensationalist journalism? Whatever. Coffee roasting is a complex business, in terms of diacetyl exposure. They focused on one worker, who mixed flavors into coffee. But diacetyl is released in the natural process of roasting coffee. If the plant is grinding coffee then there is a tremendous amount of coffee dust in the air, including diacetyl. So even if they were mixing liquid diacetyl into the coffee, as the article suggests, that is not necessarily the causative agent. Diacetyl was introduced into the air at least three completely different ways, mixing, roasting and grinding.There was a reason i repeatedly asked you ( and you repeatedly refused to answer ) if you have personally read the NIOSH studies, or relied on Skoonys interpretation. NIOSH has different sampling and analytical methods for DI/AP vapor and air borne powder, because both were present in the factories with sick workers. Here is just one example of sick workers exposed to vapor from heated liquid :
Lung-destroying diacetyl still harming workers, allowed in e-cigs
The yellow liquid used to flavor candy, chips, coffee and e-cigarettes smells and tastes like butter. It's hard to tell from looking at it that it can obliterate your lungs if you breathe it in.
Emanuel Diaz de Leon didn't know it as he poured jugs of the concentration into giant vats at a coffee roasting plant in Tyler, Texas.
Neither did his co-workers, who spent 12-hour days roasting and grinding the coated beans that would later be sold in grocery stores and restaurants nationwide as hazelnut flavored coffee.
The workers never guessed it even when they noticed they were short of breath, when what they thought were colds and allergies worsened, then never went away.
Doctors assumed they had asthma and bronchitis .....
The article suggests the worker's lungs were destroyed after only 18 months on the job, and that is consistent with the popcorn factory reports. If smoking had any relationship to this, people would be destroying their lungs in their teens. Vapers, now going on 7 years of vaping, would be dead by now. BO would be a massive epidemic in the vaping community since according to your link, 18 months is more than enough.
But we'll ignore all the inconsistencies. That stuff is surely going to kill us, even if none of it makes sense.

NOT 
