Respiratory Health and Indoor Air Quality in the Cannabis Industry

Over the past decade, there has been a dramatic expansion of the Cannabis industry in multiple US states. Although thousands of new employees are joining the workforce each year, very little is known about the occupational hazards and potential health effects for workers involved in Cannabis cultivation. Recent pilot studies have demonstrated that these workers are exposed to a variety of respiratory hazards and may be at increased risk of occupational lung diseases, particularly work-related asthma.  

Therefore, we propose a panel study to evaluate the hypothesis that exposure to specific airborne contaminants released during cannabis production is associated with impacts on respiratory health in cannabis production workers. We shall recruit a cohort of 120 cannabis workers from indoor and greenhouse cannabis cultivation facilities, and measure cannabis workers’ occupational exposure to airborne concentrations of specific contaminants associated with cannabis production. We shall also measure cross-shift spirometry and airway inflammation (FENO), cannabis sensitization and prevalence of work-related respiratory, dermal and ocular symptoms. Associations between these health endpoints and the measured exposures will be examined, in order to identify specific exposures and work activities associated with adverse health outcomes. Respiratory health measures in the cannabis worker population will also be compared to a control population including cannabis users and non-users who do not work with cannabis. Additionally, we shall design and install a local exhaust ventilation (LEV) system to capture particle and VOC emissions from the shaker-box system that is commonly used to sort and separate cannabis flower. We shall measure PM and VOC levels associated with this process, before and after installation of the LEV, to demonstrate proof of principle that the LEV system would be a cost-effective solution for reducing worker exposures.  

Based on our study findings we shall develop and disseminate a best-practices guide for cannabis employers to reduce respiratory exposures within this industry, and incorporate our study findings into worker health and safety training materials. Results from this study will provide critical information on worker respiratory exposures and associated health outcomes in this rapidly developing new industry. 

This project will:

  1. Determine cannabis workers’ occupational exposure to airborne contaminants associated with cannabis production: particle mass (PM), terpenes endotoxin, and β-glucan.
  2. Determine the prevalence of work-related health symptoms and disease, using: a) Health questionnaires of work-related respiratory, nasal, ocular, dermal symptoms; b) Skin prick test to cannabis slurry, serum total IgE and cannabis specific IgE; c) Baseline pre- and post- bronchodilator spirometry, cross-shift spirometry, and airway inflammation (FENO) on two separate workdays.
  3. ​​​​​Identify specific exposures and work activities at risk of adverse health outcomes by evaluating the association between occupational exposures and health measurements.
  4. To design, construct, install, and evaluate the effectiveness of a local exhaust ventilation system to capture particles and VOC emissions from the shaker-box system that is commonly used to sort and separate cannabis flower.
  5. To develop and disseminate occupational health and safety resources tailored to the cannabis industry.

Progress to Date

We received Institutional Review Board (IRB) approval to recruit workers in WA. We received legal clarification that we can recruit workers in Oregon and are now awaiting IRB approval to work in Oregon.
We have developed our protocols for collection of exposure measurements, questionnaire data and health measurements at the cannabis cultivation and processing facilities. We are also reaching out to employers directly, and through our collaborator – The Cannabis Alliance - to recruit worksites to participate in this study.
We met with the PNASH external science advisory board (ESAB) in May and toured a large cannabis cultivation and processing facility so that the ESAB could better appreciate the work processes and occupational health hazards associated with this industry. The ESAB provided helpful feedback to refine the research plan for this project.
Most of the supplies necessary for the health measurements have been purchased and we are currently optimizing health data collection methods. Finally, we have begun discussion with an industry partner who would supply an air cleaner to be used in a local exhaust ventilation (LEV) system to capture airborne contaminants from the shaker-box system that is commonly used to sort and separate cannabis flower.

Next Steps

We aim to begin fieldwork for this project in late fall of 2023. Field work, including exposure and health measurements, will continue for years 2-4. We plan to conduct a focus group with cannabis workers later this year to 1) identify specific production process amenable to installation of a local exhaust ventilation (LEV) exposure control, and 2) identify barriers to implementation of an LEV, and solutions to those barriers. Installation and evaluation of the LEV intervention in select worksites will take place in years 2 and 3.

Partners and Collaborators

Principal Investigators: Christopher Simpson, Professor and Assistant Chair for Research and Faculty Engagement in the UW Department of Environmental & Occupational Health Science; and Carolyn Sack, Assistant Professor in the UW Department of Environmental & Occupational Health Sciences and UW Department of Medicine.

NIOSH Funding Period 2022-2027