In recent years, sale of recreational marijuana products has been permitted in several states and countries resulting in rapid growth of the commercial cannabis cultivation and processing industry. As previous research has shown, biogenic volatile organic compounds (BVOCs) emitted from plants can react with other urban air constituents (e.g., NOx, HO radical) and thus negatively affect regional air quality. In this pilot study, BVOC emissions from Cannabis plants were analyzed at four grow facilities. The concentrations of measured BVOCs inside the facilities were between 110 and 5,500 μg m −3. One adult Cannabis plant emits hundreds of micrograms of BVOCs per day and thus can trigger the formation of tropospheric ozone (approximately 2.6 g day −1 plant −1) and other toxic air pollutants. In addition, high concentrations of butane (1,080-43,000 μg m −3), another reactive VOC, were observed at the facilities equipped with Cannabis oil extraction stations. Implications: High concentrations of VOCs emitted from Cannabis grow facilities can lead to the formation of ozone, secondary VOCs (e.g., formaldehyde and acrolein), and particulate matter. Our results highlight that further assessment of VOC emissions from Cannabis facilities is needed, and this assessment is one of the key factors for developing policies for optimal air pollution control.

Personal samplers representing 4 job classi cations and stationary samplers at 2 locations in an underground mine were deployed to measure ne particle carbon (organic/elemental), ions (sulfate plus nitrate), elements (metals and others), and speciated organic compounds including polycyclic aromatic hydrocarbons (PAH), oxygenated PAH, and hopanes/steranes. Chemically segregated size distribution was investigated after collection with a multistage impactor placed at 1 sampling site. All samples exceeded the currently proposed mine air standard of 160 ¹ g/m 3 total carbon, and most exceeded the interim standard of 400 ¹ g/m 3 . Carbon accounted for about 70% of the ne particle mass (described as a reconstructed mass of all measured chemical species); sulfate and ore/waste rock-derived metals constituted most of the remainder. Most of the personal samples were more concentrated than the ambient samples; 1 sample exceeded 2.5 mg/m 3 total mass. The PAH consisted mostly of gas-phase/semivolatile compounds and minor amounts of the particle-phase species, which is consistent with the composition of diesel exhaust, the major source of ne particle material in the mine. Size-segregated chemistry showed that the majority of the material below 1 ¹ m of aerodynamic diameter was carbon, with the largest amount at approximately 0.2 ¹ m. Metals, derived primarily from resuspended ore/waste rock, comprised the majority of the material above 1 ¹ m. Results are placed in context of current mine-monitoring techniques that aim to regulate diesel particulate material.

The chemical mass balance source apportionment technique was applied to an underground gold mine to assess the contribution of diesel exhaust, rock dust, oil mists, and cigarette smoke to airborne fine (Ͻ2.5 m) particulate matter (PM). Apportionments were conducted in two locations in the mine, one near the mining operations and one near the exit of the mine where the ventilated mine air was exhausted. Results showed that diesel exhaust contributed 78 -98% of the fine particulate mass and greater than 90% of the fine particle carbon, with rock dust making up the remainder. Oil mists and cigarette smoke contributions were below detection limits for this study. The diesel exhaust fraction of the total fine PM was higher than the recently implemented mine air quality standards based on total carbon at both sample locations in the mine.

Snowpack in alpine environments may contain appreciable levels of regional pollution acquired through natural processes of wet and dry deposition, as well as from immediate sources such as snowmobile engine exhaust. Understanding the fate and transport of pollutants in alpine environments is a crucial step towards managing emission sources in alpine terrain to mitigate their impacts on natural resources. This study presents detailed chemical analysis for 94 species of polycyclic aromatic hydrocarbons (PAH) in 55 samples of snow and surface water collected in Blackwood Canyon, a tributary to the west shore of Lake Tahoe that is a popular winter recreation area for snowmobile riders. Analyses included toxic and persistent PAH, emitted as products of incomplete combustion and useful for identifying fossil fuel combustion emissions in the environment. Average background snow PAH concentrations were used to estimate background PAH surface loading (μg.m −2 ). Loadings in excess of the estimated background are mapped and compared with observations of snowmobile activity to determine effects of snowmobile emissions on snow water quality. Loading of heavy PAH, those having three or more aromatic rings, in snow was found to be significantly greater than background loading (α = 5%) where snowmobile tracks cover more than 50% of the snow surface. Loadings were 8-20 times greater than background levels where snowmobile traffic was most concentrated over snow covered roads. PAH were also measured in snow melt and surface water samples in Blackwood Canyon for comparison with snow samples. Flux of PAH (g.day −1 ) from Blackwood Creek into Lake Tahoe was calculated and compared to estimates of background flux, increasing from 74 g.day −1 to 480 g.day −1 over an 8-day period during spring run-off.

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