Pilot study of a local exhaust ventilation system to control particle and terpene concentrations during cannabis processing

With the expansion of the U. S. legal cannabis market, there is increased awareness of health and safety concerns in the cannabis industry. Recent evidence suggests a growing burden of health symptoms in cannabis production workers, who may be exposed to toxic agents, including respiratory irritants and allergic sensitizers, during their job activities. Swift action is warranted to protect this expanding workforce by characterizing and controlling airborne exposures during cannabis production.

To help address these concerns, we developed a local exhaust ventilation (LEV) system with a partially-enclosed hood to control particle and terpene emissions during cannabis processing activities using a minimum efficiency reporting value (MERV)-13 filter (particles) and an activated charcoal filter (terpenes). Inhalable particulate matter (PM) and total terpene air concentrations were compared with and without the LEV system across three separate paired trials during whole flower grinding and automated pre-roll joint filling.

On average, the LEV system reduced inhalable PM concentrations by 95% during whole flower grinding and 83% during pre-roll joint filling. The LEV system was similarly effective in controlling total terpenes, reducing concentrations to below the limit of detection (LOD) during whole flower grinding.

To date, this is the first study to evaluate the efficacy of LEV as an exposure control during cannabis processing. These preliminary results suggest that the partially-enclosed hood LEV system is an effective exposure control for cannabis processing activities. Findings from this study can guide future industrial hygiene interventions that protect cannabis workers from potentially harmful exposures.