Denver-based Green Dragon grows its popular Death Star marijuana strain inside a 120,000 foot greenhouse. The set-up helps the company save money on electricity.

(Grace Hood/CPR News)

Three years after Colorado began selling legal marijuana, buyers have access to extra-potent pot. Cannabis-concentrate products like Shatter can reach up to 90 percent tetrahydrocannabinol, or THC, the main psychoactive compound in marijuana. 

Researcher Kent Hutchinson of the University of Colorado Boulder Change Lab studies how marijuana potency relates to cognition and health, and how THC works alongside another cannabis compound, cannabidiol, or CBD. He tells Colorado Matters host Ryan Warner how the chemicals might affect pain, anxiety and impairment.