Marijuana Could Worsen Air Pollution
Volatile organic carbons (VOCs) react with nitrogen oxides and sunlight to form the pollutant ozone, which can contribute to smog. A recent study found that marijuana produces large amounts of potent VOCs called terpenes. The pot farms around Denver, CO are so numerous and so large scale that the VOCs emitted potentially double the smog pollution for the city. You can find more information about the research in the following article from Science News:
http://www.sciencemag.org/news/2019/01/legal-pot-farms-expand-so-do-air-pollution-worries