The marijuana industry has air quality impacts beyond just nuisance odors. Recent studies have found that cannabis plants emit gas phase terpenes. Terpenes are a type of Volatile Organic Compound (VOC). The industry also uses solvents for extracting concentrates that result in VOC emissions. These types of VOCs chemically react with nitrogen oxides (NOx) emissions in the presence of sunlight to form ground level ozone. Ozone is an air pollutant that is harmful to human health and negatively impacts the environment. With the rapid growth of the marijuana industry, due to the legalization of cultivation and manufacturing, there is now an unknown industrial scale area source of VOCs that can impact ozone formation. This is especially important in VOC-limited areas, such as urban areas with high concentrations of nitrogen oxides, where increases in VOCs can have a significant impact on ozone production. The Colorado Department of Public Health and Environment has conducted research to quantify the unknown rate of VOC emissions from industrial scale cannabis cultivation and model the resulting impacts on local ozone formation in Colorado.
Separately, the marijuana industry routinely releases carbon dioxide, purchased as a byproduct of power generation, into the indoor cultivation environment to stimulate accelerated plant growth. Carbon dioxide is a greenhouse gas that contributes to climate change. CDPHE participated in an innovative pilot project to capture waste carbon dioxide emissions from local breweries with new equipment, purify it, and recycle it during the cannabis cultivation process.
Throughout the fermentation process breweries emit carbon dioxide at a much higher quantity than is used to carbonate beer and pressurize lines throughout the facility. Typical practice is for breweries to vent all carbon dioxide from the fermentation process and purchase carbon dioxide from an outside supplier. This small scale carbon capture demonstration pilot between breweries and a cannabis cultivation was to demonstrate the ability to capture the carbon dioxide waste stream and reuse it as an input to the marijuana growing process, therefore reducing carbon dioxide emissions in Colorado.