Table 1.

Survey questions administered to participants before semi-structured interview.

Preamble	The next questions are about the use of marijuana, which is also called cannabis. Marijuana is often used for fun or medical purposes, and people can smoke, eat, or vape it. When answering please include marijuana in all forms, including leaves and buds, powder/wax, glass/shatter, hashish, hash oil, resin, and all parts of the dried plant.
Past 30-day marijuana use	In the past 30 days have you used any type of marijuana? Yes, No
Past 30-day marijuana-tobacco co-use	In the past 30 days, have you used marijuana and tobacco or nicotine products together at the same time (e.g. in a spliff, blunt, or moke)? Yes, No
Number of days marijuana use, past 30	During the past 30 days, how many days did you use any type of marijuana? 0–30
Number of days marijuana-tobacco co-use, past 30	During the past 30 days, how many days have you used marijuana and tobacco or nicotine products together at the same time (e.g. in a spliff, blunt, or moke)? 0–30
Preamble	The next set of questions focuses on different ways that you may have used marijuana in the past 30 days, including joints, spliffs, blunts, pipes, bongs, vaporizers and dab rigs.
Preamble	A joint is rolled with marijuana only. A spliff is rolled with marijuana and tobacco mixed together.
PastS 30-day joint use	In the past 30 days, have you smoked a joint rolled with only marijuana? Yes, No, Prefer not to answer
Past 30-day spliff use	In the past 30 days, have you smoked a spliff rolled with marijuana and tobacco mixed together? Yes, No, Prefer not to answer
Preamble	Sometimes people take some tobacco out of a cigar and replace all or some of it with marijuana, or roll marijuana using a blunt wrap. This is sometimes called a “blunt.”
Past 30-day blunt use	In the past 30 days, have you smoked a blunt? Yes, No, Prefer not to answer
Past 30-day pipe use	In the past 30 days, have you smoked marijuana using a pipe? (Do NOT include bongs or waterpipes) Yes, No, Prefer not to answer
Past 30-day pipe co-use	When you smoked marijuana using a pipe in the past 30 days, did you ever mix tobacco in with the marijuana? Yes, No, Prefer not to answer
Past 30-day bong use	In the past 30 days, have you smoked marijuana using a bong or waterpipe? Yes, No, Prefer not to answer
Past 30-day bong co-use	When you smoked marijuana using a bong or waterpipe in the past 30 days, did you ever mix tobacco in with the marijuana? Yes, No, Prefer not to answer
Preamble	The next few questions are about vaporizers that are used to vape marijuana. These include larger table-top vaporizers (such as Volcano) and smaller, portable vaporizers such as e-joints or vaporizer pens, but do not include dab rigs.
Past 30-day oil vape use	In the past 30 days, have you used a vaporizer with hash oil or marijuana concentrates (such as hash, wax, resin, shatter, or budder)? Yes, No, Prefer not to answer
Past 30-day flower vape use	In the past 30 days, have you used a vaporizer with dried marijuana leaves, buds, or flowers? Yes, No, Prefer not to answer
Past 30-day vape co-use	In the past 30 days, have you used a vaporizer with marijuana and tobacco (dried loose tobacco or nicotine liquid) together? Yes, No, Prefer not to answer
Preamble	Next, we would like to ask about use of marijuana with a dab rig. Dab rigs are water-filled devices (similar to a bong) that often have a metal, glass, or quartz bowl (commonly called a “nail”) that is heated with a torch. Once the nail is very hot, the user touches marijuana concentrate to it using a stick or “dabber.” This produces a vapor that is inhaled through the dab rig’s mouthpiece.
Past 30-day dab rig use	In the past 30 days, have you used a dab rig with marijuana? Yes, No, Prefer not to answer
Past 30-day edible use	In the past 30 days, have you used edible marijuana (food, candy, or drink made with marijuana)? Yes, No, Prefer not to answer
Preferred co-use method	What is your preferred way of using marijuana and tobacco (dried loose tobacco or nicotine liquid) together? Spliff, Blunt, Pipe, Bong or waterpipe, Vaporizer; Smoking a cigarette, cigar, or cigarillo while high from smoking or vaping marijuana; Vaping nicotine while high from smoking or vaping marijuana, Some other way (describe), I do not have a favorite way, Prefer not to answer