Kent Micronite filters contained blue crocidolite asbestos. Of the 6 known types of asbestos, crocudolite is the most toxic/harmful.

One study revealed smoking a pack of Kent Micronite cigarettes every day for a year would expose a smoker to 131 million carcinogenic crocidolite fibers.

A 1989 study of 33 people who worked in the Hollingsworth & Vose filter factory in 1953 found 28 of them died from asbestos-related diseases, including asbestosis, lung cancer and mesothelioma.