Hi, I am Dr. William Vizuete, Chief Scientific Officer at Pacific Environmental Analytics. For the past six years I have led a team of cannabis industry experts focused on site-specific research to increase overall knowledge of cannabis industry emissions, educate local communities and improve the tools and methods that cultivators and policymakers use to better evaluate the environmental impacts of cannabis cultivation, processing and manufacturing. Over the next year I will host a discussion each month on a particular cannabis-related topic with the goal of improving our collective understanding of a variety of facets that impact the overall cannabis industry.

In this our inaugural edition I would like address Cannabis Terpenoid Emission Factor Measurements for the purposes of measuring the potential impacts of cannabis cultivation on air quality. The overall goal of this project was to quantify the emission capacities of various cannabis strains at both juvenile and mature growth stages in order to investigate their potential impact on atmospheric distributions of terpenoids and other biogenic volatile organic compounds (BVOCs). Although there are existing models available for estimating BVOC emissions, the lack of emission factors for cannabis strains limits accurate estimation of their emission rates. Therefore, the quantification of speciated emission factors for a comprehensive range of terpenoid compounds and other BVOC is required in order to know the impact of a specific strain of cannabis. To accomplish this, we conducted enclosure measurements of terpenoid emissions from cannabis strains growing in a greenhouse environment and calculated emission factors in ug g-1 h -1 (micrograms compound per gram dry weight per hour at leaf conditions of temperature= 30°C and light = 1000 umol visible light m-2 s -1). The primary output is a dataset of terpenoid emission factors that is suitable for use in biogenic emission models that drive air quality simulations.

Emissions of reactive gases from the Earth’s surface drive the composition of the atmosphere including the constituents relevant for regional air quality. Emissions of some compounds, including terpenoid compounds from vegetation, are highly variable and can vary more than an order of magnitude over spatial scales of a few kilometers and time scales of less than a day (Wang et al. 2019). This makes estimation of these emissions especially challenging and yet accurate quantification and simulation of these fluxes is a necessary step towards developing air pollution control strategies and for attributing observed atmospheric composition changes to their causes. Biogenic VOC (BVOC) emission models assume that emission rates are the product of an emission factor (EF) and an emission activity factor, similar to the approach used for most anthropogenic emission estimates. While research activities tend to focus on emission activity factors, it is clear that uncertainties in EF are significant and for plant species with few or no emission factors or highly variable chemotypes, such as Cannabis, EF uncertainties dominate the total uncertainty in BVOC emission rate estimates. Measurements of individual varieties and growth stages are thus required to quantify emissions from this source.

What did our studies reveal to help you better understand the cannabis business? Leaf enclosure studies to measure cannabis emission factors provide a wealth of data that provide whole new insights into the cannabis plant biology and its potential impact, or lack thereof, on air quality and the overall environment.