Ketene emission and exposure thresholds. The results herein show ketene formation across different starting cannabinoid acetates and from both dabbing and e-cigarette cartridge vaping. There is a lack of peer-reviewed information concerning user preferences and vaping topography regarding cannabis products. However, it is well-known that dabbing involves large inhalation volumes, approaching full lung capacity (~ 0.005 m 3 ). The 5.0 ppm threshold established by NIOSH for ketene exposure equates to 8.6 mg/m 3 , using 1 ppm = 1.72 mg/m 3 . In a 0.005 m 3 lung volume, the NIOSH threshold value is thus 0.043 mg ketene. The 0.078 mg yield of ketene obtained from a CBN-OAc dab is therefore above the NIOSH threshold. When the ∆ 8 -THC-OAc sample was dabbed, the amount of ketene produced was lower (0.022 mg).