Hm, all zeolite sources I have looked at were described as 'zero to something' in particle size. I guess running through 3um filter paper multiple times should be.. okay? I guess?

The risk status of zeolite seems to be quite up in the air. There is one specific form of zeolite that is considered almost as bad as asbestos, but in general only chronic exposure to a lot of inhaled zeolite seems to be indicated as a risk on most material safety sheets.

I wonder how one would assess the risk of vaping a filtered thc/cbd isolate vs. for example smoking a joint (or spending a day in a downtown with traffic).

It's not about burning, it's about inhaling. It's stone dust.

[URL unfurl="true"]https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/erionite[/URL]

[URL unfurl="true"]https://www.zeolite.guide/understanding-zeolite-uses-benefits-and-potential-side-effects/[/URL]