TY - JOUR

T1 - Ambient measurements of monoterpenes near Cannabis cultivation facilities in Denver, Colorado

AU - Wang, C.-T.

AU - Ashworth, K.

AU - Wiedinmyer, C.

AU - Ortega, J.

AU - Harley, P.C.

AU - Rasool, Q.Z.

AU - Vizuete, W.

N1 - This is the author’s version of a work that was accepted for publication in Atmospheric Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Atmospheric Environment, 232, 2020 DOI: 10.1016/j.atmosenv.2020.117510

PY - 2020/7/1

Y1 - 2020/7/1

N2 - Colorado was one of the first US states to legalize the industrial-scale cultivation of Cannabis spp. for recreational purposes. In March 2018, there were 609 indoor Cannabis cultivation facilities (CCFs) in operation in Denver County with a recorded 550,000 mature plants (higher than 8 inches) under cultivation at any given time. It is known that cultivation of Cannabis spp. produces emissions of a group of highly reactive hydrocarbons, monoterpenes. There have been limited studies that have quantified mixing ratios of emitted monoterpenes in air outside CCFs. A field campaign was conducted in August 2016 in Denver County focused on six different CCF clusters near the intersection of interstate highways I-25 and I-70 during which a total of 150 ambient air samples were collected. Monoterpene mixing ratios near CCFs were ~408 ± 203 pptv; 4–8 times higher than samples collected from a “background” site located at the Denver City Park (75 ± 25 pptv). The composition of samples taken near CCFs were dominated by d-limonene (30%), β-myrcene (20%), and α-pinene (15%), which is similar to previously reported emission factors for Cannabis spp. Since β-myrcene was only detected in leaf enclosure studies, indoor CCF observations and ambient samples near CCFs and not detected at a background site, this particular compound could be used as a tracer for the Denver Cannabis production industry. The monoterpene speciation in ambient measurements varied across Denver suggesting differences in emissions between different Cannabis spp., or different growth stages. Given the observed variabilities in both composition and emission rates, it is critical for the accuracy of emissions inventories to develop strain-specific emission factors. This information, coupled with detailed information on each CCF, would greatly reduce the uncertainties currently present in monoterpene emission estimates for the Cannabis industry and their potential impact on air quality. © 2020 Elsevier Ltd

AB - Colorado was one of the first US states to legalize the industrial-scale cultivation of Cannabis spp. for recreational purposes. In March 2018, there were 609 indoor Cannabis cultivation facilities (CCFs) in operation in Denver County with a recorded 550,000 mature plants (higher than 8 inches) under cultivation at any given time. It is known that cultivation of Cannabis spp. produces emissions of a group of highly reactive hydrocarbons, monoterpenes. There have been limited studies that have quantified mixing ratios of emitted monoterpenes in air outside CCFs. A field campaign was conducted in August 2016 in Denver County focused on six different CCF clusters near the intersection of interstate highways I-25 and I-70 during which a total of 150 ambient air samples were collected. Monoterpene mixing ratios near CCFs were ~408 ± 203 pptv; 4–8 times higher than samples collected from a “background” site located at the Denver City Park (75 ± 25 pptv). The composition of samples taken near CCFs were dominated by d-limonene (30%), β-myrcene (20%), and α-pinene (15%), which is similar to previously reported emission factors for Cannabis spp. Since β-myrcene was only detected in leaf enclosure studies, indoor CCF observations and ambient samples near CCFs and not detected at a background site, this particular compound could be used as a tracer for the Denver Cannabis production industry. The monoterpene speciation in ambient measurements varied across Denver suggesting differences in emissions between different Cannabis spp., or different growth stages. Given the observed variabilities in both composition and emission rates, it is critical for the accuracy of emissions inventories to develop strain-specific emission factors. This information, coupled with detailed information on each CCF, would greatly reduce the uncertainties currently present in monoterpene emission estimates for the Cannabis industry and their potential impact on air quality. © 2020 Elsevier Ltd

KW - Ambient measurement

KW - Cannabis Cultivation

KW - Cannabis spp.

KW - Monoterpene

KW - Air quality

KW - Highway engineering

KW - Mixing

KW - Uncertainty analysis

KW - Denver , Colorado

KW - Different growth stages

KW - Emissions inventory

KW - Industrial scale

KW - Monoterpene emissions

KW - Potential impacts

KW - Production industries

KW - Monoterpenes

KW - air quality

KW - ambient air

KW - atmospheric pollution

KW - cultivation

KW - emission inventory

KW - growth

KW - monoterpene

KW - tracer

KW - Colorado

KW - Denver County

KW - United States

KW - Cannabis

U2 - 10.1016/j.atmosenv.2020.117510

DO - 10.1016/j.atmosenv.2020.117510

M3 - Journal article

VL - 232

JO - Atmospheric Environment

JF - Atmospheric Environment

SN - 0004-6981

M1 - 117510

ER -