AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Characteristics of Secondhand Marijuana Smoke: PM2.5 Calibration Factors and Emission Strengths
TONGKE ZHAO, Kai-Chung Cheng, Wayne Ott, Lance Wallace, Lynn M. Hildemann, Stanford University
Abstract Number: 389 Working Group: The Air We Breathe: Indoor Aerosol Sources and Chemistry
Abstract The widespread legalization of recreational marijuana use has led to growing concerns about exposure to secondhand marijuana smoke (SHMS). Similar to cigarette smoke, SHMS contains particulate matter (i.e. PM2.5, ultrafine particles), volatile organic compounds and carbon monoxide; in addition, it contains tetrahydrocannabinol and cannabidiol, which are well-known to cause adverse health effects. However, there are few studies characterizing SHMS.
To accurately assess PM2.5 concentrations in SHMS, we first focused on determining PM2.5 calibration factors for particles from typical types of marijuana consuming: glass pipe, joint, bong, and vaping pen. SHMS was introduced by a habitual marijuana user into a ~5 m3 chamber. To derive PM2.5 calibration factors, measurements from real-time optical PM2.5 monitors (SidePak AM510 Personal Aerosol Monitor, TSI Inc., Shoreview, MN) were compared with gravimetric mass. In addition, PM2.5 emission strengths for each marijuana type were calculated as μg/puff and were compared with the values for exhaled mainstream smoke from traditional cigarette smoking.
The real-time monitor’s PM2.5 calibration factors for SHMS from a glass pipe, a joint, a bong, and a vaping pen were found to be 0.30 (SE=0.02), 0.40 (SE=0.02), 0.43 (SE=0.01), and 0.43 (SE=0.03), respectively. These calibration factors will enable more accurate real-time measurements of exposure to SHMS in field settings using portable real-time monitors.
The PM2.5 emission strengths of the aforementioned SHMS sources were 1.4 (SD=0.6), 4.9 (SD=0.7), 1.6 (SD=0.5), and 1.4 (SD=0.4) mg/puff, respectively. These values are ~2‒6 times larger than emission strengths measured for exhaled mainstream smoke from traditional cigarettes, using the same approach (i.e. 0.8 (SD=0.5) mg/puff).