AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Exposure to Particulate Matter at an Outdoor Marijuana Consuming Event
TONGKE ZHAO, Kai-Chung Cheng, Wayne Ott, Lance Wallace, Lynn M. Hildemann, Stanford University
Abstract Number: 390 Working Group: Aerosol Exposure
Abstract On April 20th of each year, marijuana enthusiasts gather at open public places to celebrate and consume marijuana together starting exactly at 4:20 pm. High levels of secondhand exposure to marijuana emissions may occur at these events, as well as at other special events (e.g. rock concerts) which allow marijuana smoking. To assess secondhand exposure to marijuana, we monitored airborne particle concentrations at outdoor marijuana consuming event on April 20th, where ~ 1500 people gathered in a ~20 ×50 m meadow.
PM2.5 concentrations and ultrafine particle concentrations were measured by two optical particle monitors (SidePak AM510, TSI Inc., Shoreview, MN) and a condensation particle counter (CPC 3007, TSI Inc., Shoreview, MN), respectively, before, during, and after the event, which lasted about 13 minutes. A calibration factor was applied to the SidePak data to estimate PM2.5 mass.
The background before the event was only 1.5 μg/m3 (SD=1.4 μg/m3). During the event’s active-consuming period, between 4:20 and 4:33 pm, the mean PM2.5 concentrations were 300 μg/m3 (SD=408 μg/m3) in the crowded meadow. The maximum 1-second peak PM2.5 concentration was >3000 μg/m3. In an unoccupied space away from the meadow, a peak PM2.5 concentration of ~600 μg/m3 was measured when a single active marijuana smoker passed nearby.
The mean particle number concentration during the event’s active-consuming period was 5.6×104 particles/cm3 (SD=5.6×104 particles/cm3) whereas the background before the event was only 621 particles/cm3 (SD=113 particles/cm3). The maximum 1-second particle number concentration reached 1.9×105 particles/cm3. Spearman Correlation factor between PM2.5 mass concentrations and particle number concentrations was 0.74 (p<0.01).