What topics does this cannabis study cover?

This study covers research on: THC, CBD.

Where was this research published?

Published in Journal of breath research on January 13, 2026.

THC exists mainly as vapor in breath, not aerosol droplets

Q: What did this research study find?

**All three cannabinoids (*THC*, *CBD*, and *CBN*) exist primarily in the vapor phase** of exhaled breath at body temperature, contradicting the common assumption that they are carried only in aerosol droplets

Vapor pressure measurements on Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol to inform cannabis breathalyzer development.

Journal of breath research • January 13, 2026 • Highly Relevant

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AI Summary

This groundbreaking study challenges a fundamental assumption about cannabis breathalyzer technology by demonstrating that THC, CBD, and CBN exist primarily in vapor form rather than in aerosol droplets in exhaled breath. Using precision measurements at temperatures ranging from 364 K to 424 K (approximately 91°C to 151°C), researchers determined the vapor pressure of these three major cannabinoids and extrapolated the findings to human body temperature. The measurements revealed that CBD has the highest vapor pressure (0.0826 Pa to 13.44 Pa), followed by THC (0.0459 Pa to 7.833 Pa), and CBN (0.0199 Pa to 5.678 Pa). Most significantly, their vapor-aerosol partitioning model predicted that all three cannabinoids reside predominantly in the vapor phase of breath at body temperature, not carried on aerosol particles as commonly assumed.

These findings have major implications for cannabis detection technology and forensic testing. Current breathalyzer devices designed to capture only aerosol particles may be missing the majority of cannabinoids present in breath, which could explain the large variabilities observed in breath THC measurements. The research demonstrates that accurate cannabis breath testing requires devices capable of collecting both vapor and aerosol phases. However, the study also revealed that relatively small changes in temperature or aerosol concentration can significantly affect how cannabinoids partition between phases, adding complexity to breathalyzer design. This work provides critical scientific data needed to develop more reliable forensic drug tests and clinical diagnostics based on breath analysis.

💡 Key Findings

All three cannabinoids (THC, CBD, and CBN) exist primarily in the vapor phase of exhaled breath at body temperature, contradicting the common assumption that they are carried only in aerosol droplets

High

85%

CBD has the highest vapor pressure among the cannabinoids tested (0.0826 Pa to 13.44 Pa), followed by THC and then CBN, indicating CBD is the most volatile

High

90%

Current breathalyzer devices that only collect aerosols may be missing the majority of cannabinoids in breath, potentially explaining the large measurement variabilities reported in previous studies

High

80%

Small changes in temperature or aerosol concentration can significantly impact cannabinoid partitioning between vapor and aerosol phases, complicating breathalyzer design and accuracy

High

85%

📄 Original Abstract

Δ9-tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, and other drug molecules that have large molar masses, are often described as "nonvolatile" and are presumed to be carried in exhaled breath aerosols. Large variabilities in THC concentrations in breath have been measured with devices that only collect aerosols; it is possible that neglecting the vapor phase could be responsible. Partitioning of compounds between vapor and aerosol phases is directly dependent on vapor pressure (psat), which itself is strongly dependent on temperature. We describepsatmeasurements for THC, cannabidiol (CBD), and cannabinol (CBN) using a gas-saturation apparatus. The measured values ofpsatfor 364 K to 424 K are 0.0459 Pa to 7.833 Pa for THC, 0.0826 Pa to 13.44 Pa for CBD, and 0.0199 Pa to 5.678 Pa for CBN. The combined standard (k= 1, 68 % confidence) measurement uncertainty inpsatranges from 2.9 % to 5.3 % for CBD and CBN, and from 5.2 % to 9.5 % for THC. To obtain thepsatat human body and exhaled breath temperatures, we extrapolated the measurements for each cannabinoid with a thermodynamic correlation. Then a vapor-aerosol partitioning model was used to predict mole fractions of each cannabinoid in each phase of exhaled breath. All three cannabinoids were predicted to reside primarily in the vapor phase of exhaled breath. However, relatively small changes in temperature or aerosol concentration can significantly impact the predicted partitioning. This work illustrates the utility of low-uncertaintypsatmeasurements for any drug, including those thought to be too low in volatility for vapor-phase sampling, and may extend the market for forensic drug tests and clinical diagnostic tests via breath analysis.

Paper Type

📄 Research

Publication

Journal: Journal of breath research
Published: January 13, 2026
PMID: 41529405
DOI: 10.1088/1752-7163/ae3794

Authors (7)

Cheryle Beuning Applied Chemicals and Materials Division, National Institute of Standards and Technology, 325 Broadway, MS 647.07, Boulder, Colorado, 80305, UNITED STATES.
Jennifer Berry Applied Chemicals and Materials Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado, 80305, UNITED STATES.
Eugene Paulechka National Institute of Standards and Technology Applied Chemicals and Materials Division, 325 Broadway, Boulder, Colorado, 80305-3337, UNITED STATES.
Marcia Huber National Institute of Standards and Technology Applied Chemicals and Materials Division, 325 Broadway, Boulder, Colorado, 80305-3337, UNITED STATES.
Kavita M Jeerage Applied Chemicals and Materials Division, National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado, 80305, UNITED STATES.
+2 more authors