Electronic cigarettes convert a specially formulated liquid into a vapor which the person inhales in a manner that mimics the way one inhales from a traditional cigarette. The liquid (which is sometimes called “juice”, “smoke-juice” or similar names) typically includes kosher-sensitive ingredients such as glycerin and flavors, and since the person imbibes the liquid/vapor, Rav Schwartz said that the liquid must be certified as kosher. We contacted a number of manufacturers who claim to use only kosher raw materials but there is no independent agency who certifies that claim, and therefore we are unable to recommend those products. [As with all medical issues, one should consult with their doctor before deciding to use or not use electronic cigarettes.]
Based on something I wrote in the previous post (Synopsis of YD §108), I disagree. For the record, I am simply elaborating on what I have already written here and here.