Fine and UltrafineParticle Concentrations in a CannabisConsumption Lounge

With widespread adult-use cannabis legalization in the United States, cannabis consumption lounges have rapidly emerged. However, studies of indoor cannabis exposure are still lacking, particularly in public spaces. We measured fine particle (PM_2.5) mass concentrations and particle number concentrations at a cannabis consumption lounge in Los Angeles, California. We compared particle concentrations at the street front, backyard, and two smoking cabins and identified three busyness levels to investigate concentration differences in the smoking cabin. The results showed that PM_2.5 concentrations in the smoking cabin exceeded 1600 μg/m³. During busy hours (12:00 p.m. to 10:00 p.m.), the median (IQR) PM_2.5 concentration [31.2 (317.3) μg/m³] was >10 times higher than overnight (10:00 p.m. to 9:00 a.m.) concentrations [3.0 (1.3) μg/m³] and >3 times higher than concentrations [8.5 (13.8) μg/m³] during less busy hours (9:00 a.m. to 12:00 p.m.). The particle number concentration during active cannabis use [median of 1.9 × 10⁴, interquartile range (IQR) of 1.3 × 10⁴ particles/cm³] was significantly higher than the baseline (median of 0.9 × 10⁴, IQR of 0.3 × 10⁴ particles/cm³). Our research shows high fine and ultrafine particle concentrations in a cannabis consumption lounge, which could facilitate future studies of related health effects and the development of targeted regulations.