The Johns Hopkins Study
In 2018, researchers at Johns Hopkins Medicine published a landmark study comparing vaporized cannabis to smoked cannabis at identical doses.
The results weren't close.
At 10mg THC, vapers hit 7.5 ng/ml blood THC on average. Smokers hit 3.8 ng/ml. At 25mg, vapers reached 14.4 ng/ml vs smokers' 10.2 ng/ml. Nearly double the THC actually making it into the bloodstream.
The subjective effects matched: vapers reported significantly greater drug effects, more cognitive impairment, and made roughly twice as many errors on cognitive tests compared to smokers using the same dose.
The Numbers
At 10mg THC: 7.5 ng/ml (vaping) vs 3.8 ng/ml (smoking)
At 25mg THC: 14.4 ng/ml (vaping) vs 10.2 ng/ml (smoking)
Source: Johns Hopkins Medicine, 2018
Why Vaping Delivers More THC
The explanation is straightforward: combustion destroys cannabinoids.
When you smoke cannabis, the cherry of your joint or bowl reaches over 800°C (1472°F). A significant portion of the THC is literally burned before it can reach your lungs. What doesn't burn combines with combustion byproducts like tar and carbon monoxide.
Vaporization heats cannabis to a much lower temperature, typically 160-230°C (320-446°F). That's hot enough to release cannabinoids and terpenes from the plant material, but not hot enough to burn them. No material is lost to combustion.
The researchers put it simply: "The difference is most likely due to some destruction of the drug when the cannabis is burned, which doesn't occur when it is vaporized."
Head-to-Head Comparison
| Factor | Vaping | Smoking |
|---|---|---|
| THC Delivery | Higher (no combustion loss) | Lower (some destroyed by heat) |
| Onset | Fast (seconds to minutes) | Fast (seconds to minutes) |
| Duration | 1-3 hours | 1-3 hours |
| Flavor | Cleaner, more terpene-forward | Smokier, charred notes |
| Smell | Less lingering odor | Strong, persistent smell |
| Combustion Byproducts | None | Tar, carbon monoxide, etc. |
| Convenience | Highly portable, discreet | Requires rolling/packing |
Types of Vapes
Not all vapes are the same. The two main categories:
Dry Herb Vaporizers
These heat actual cannabis flower without burning it. You load ground bud into a chamber, the device heats it to release cannabinoids as vapor. The experience is closest to smoking: same material, different method.
Potency depends on the flower you use. A 20% THC flower vaped will be more efficient than smoking, but still flower-level potency.
Concentrate Vapes (Cartridges/Pens)
These vaporize cannabis extracts: distillate, live resin, liquid diamonds, or blends. The concentrate is already highly refined, often 70-95% THC.
This is where dosing gets serious. A 1g cartridge at 80% THC contains 800mg of THC. A 1g pre-roll at 20% THC contains 200mg (and you lose some to combustion). The difference is massive.
Dosing Guidance for Vape Beginners
If you're used to smoking flower and trying concentrates for the first time, go slow. Really slow.
- Start with one small hit. A 2-3 second draw. That's it.
- Wait 10-15 minutes. Effects come on fast but can intensify. Don't stack hits before you know where the first one lands.
- Understand the math. A cart with 80% THC delivers ~40mg per puff. A joint might deliver 5-10mg per puff with combustion loss. The numbers aren't comparable.
- Your smoking tolerance doesn't fully transfer. Concentrate highs can feel different, more intense, sometimes more heady. Give yourself time to calibrate.
The Rice Grain Rule
For dabbing concentrates, a piece the size of a grain of rice (about 25-30mg of extract) is a reasonable starting dose. For vape pens, one small hit achieves something similar. You can always take more. You can't take less.
Is Vaping Safer Than Smoking?
This is a more complicated question than people want it to be.
What we know: Vaping avoids combustion, which means no tar, carbon monoxide, or other combustion byproducts. Some studies suggest cannabis vapers report fewer respiratory symptoms than smokers.
What we don't know: Long-term effects of inhaling vaporized concentrates aren't fully understood. The 2019 vape lung illness outbreak (EVALI) was linked to vitamin E acetate in illicit cartridges, not regulated cannabis products. But it highlighted that vaping isn't inherently risk-free.
The honest take: Vaping likely exposes you to fewer harmful compounds than smoking. But neither is "safe" in an absolute sense. If respiratory health is a priority, edibles avoid inhalation entirely.