A vaporizer (or vaporiser) is a device used to release the active ingredients of plant material, commonly cannabis, tobacco, and many other therapeutic or medicinal herbs or blends (phyto-inhalation; see also: aromatherapy). Vaporization is an alternative to smoking. Rather than burning the herb, which produces numerous harmful by-products, a vaporizer heats the material in a controlled manner so that the active compounds contained in the plant boil off into a vapor. This new gas is not smoke from combustion, but an evaporated vapor that has the appearance of light smoke. The vapor ideally contains virtually zero particulate matter (tar) and reduced noxious gases such as carbon monoxide. Vapor may be filtered and cooled further using a water pipe or an inline water/ice attachment. The vapor is then inhaled directly through a hose or pipe for highest activity, or stored for subsequent inhalations in a container such as a "dome" or "balloon." With little to no smoke produced, cooler temperatures, and less material required to achieve the same effect, the irritating/harmful effects of smoking are greatly reduced or eliminated, along with second hand smoke, by using a vaporizer. This makes vaporizers useful in places where there are public bans on smoking and under circumstances in which a more medical-like delivery medium is preferred.
Several scientific studies have been done showing that vaporization is superior to smoking healthwise for the delivery of medical cannabis and cannabis in general. Vaporizers, especially the old ones, can show great variation according to technology. When using high-end vaporizers along with high grade cannabis (containing elevated levels of THC), all undesired compounds are found to be eliminated, in a manner consistent enough for clinical trials. In comparison to other THC delivery methods such as ingestion, vaporization offers the advantages of: rapid onset, direct delivery into the bloodstream (via the lungs), and the possibility of gradually increasing delivery until the desired level is reached, enabling more effective self-dosage.
Vaporizers are available in many varieties and price ranges.
Simple vaporizers commonly use a jet flame lighter as a heat source. Although common lighters can also be used, jet flame or torch lighters are preferred, because they don't stain the vaporizer pipes with soot.
Precise vaporizers use an electric heating element, often featuring a temperature control and thermo-couple for accurate thermal exchange. High-end models may cost several hundred U.S. dollars.
Broadly, vaporizers may be classified by how they heat the substance:
In conduction heating, the substance is placed on a metal plate that is then heated to release the active constituents. Conduction vaporizers were the first type to appear on the market, and some are still made today. The direct contact between hot metal and the herbs can cause them to burn; thus this is not a preferred approach and is rarely used in modern vaporizer designs. This design also relies on a collection dome in most cases and the prolonged exposure of the vapor to air during the collection phase and prior to the inhalation phase is known to decrease bio-activity via oxidation.
In convection heating, the substance itself never touches a heating element. Instead, hot air passes through it, heating it rapidly, and allowing the release of the active constituents. This method of heating releases more active constituents than conduction heating, especially if the extraction chamber utilizes Venturi effect design such as seen in proprietary vaporization chamber bowls.
In radiation heating, the substance is subjected to bright light. The substance absorbs radiant energy and its temperature rises. Radiation vaporizers are rare but capable of duplicating the performance of convection vaporizers.
Most vaporizers deliver dry vapor: that is vapor that is extracted and delivered dry. Usually a cooling of the vapor takes place between the point of extraction and the point of delivery, but the dry warm nature of this kind of vapor will often irritate the throat and upper tracheo bronchial tree. It must be remembered that at least in terms of Cannabis, heat is the primary culprit leading to damage of the tracheo-bronchial tree whether smoking or vaporizing. Cannabis smoke contains tars and noxious gases known to be harmful not present in accurately extracted vapor; however, THC is a powerful expectorant and will cause the tars consumed to be subsequently coughed up (unlike nicotine which does not have a medicinal expectorant quality). Vaporizers or vaporization systems that feature rapid extraction and delivery combined with water / ice cooling and conditioning of the vapor deliver the best of all: cleaner more concentrated and aromatic inhalations of vapor that is cooled and moisturized for maximized bio-activity and minimized impact.
Regardless of the benefits of medical cannabis, the widely perceived health risks of smoking as a route of administration have been viewed as a major obstacle for the legal approval of cannabis for medical uses, though some studies indicate that the expectorant activity of THC may help the lungs remove much of the inhaled tar through coughing. In response to the concerns, several studies have aimed to establish whether or not vaporizers could offer a clinically reliable and safe route of administration for cannabis. Though vaporizers show great variations in performance, such studies have consistently found vaporization superior to smoking and with best case (high-end vaporizers used with potent cannabis) results showing an elimination of undesired compounds suitable for clinical trials. In comparison to other routes of administering cannabis such as eating, vaporization offers the advantages of inhalation - immediate delivery into the bloodstream, rapid onset of effect, and more precise titration, the ability to more accurately control the dosage to produce a desired effect.
All Studies have found the release of harmful constituents dramatically reduced or completely eliminated. Substantial reductions were also found for the M1-volatizer. However, a 1996 study including two simple vaporizers still found ten times more tar in the vapor than THC, although this was nevertheless up to a 30% improvement compared to the best alternative smoking method.
The most recent study, published in the Journal of Psychopharmacology in May 2008, investigated the acceptability and usefulness of intrapulmonary THC administration using a Volcano Vaporizer and pure THC instead of cannabis. Rising doses of THC (2, 4, 6 and 8 mg) were administered with 90 minutes intervals to twelve healthy males. Very low between-subject variability was observed in THC plasma concentrations, characterising the Volcano Vaporizer as a suitable method for the administration of THC.
In 2007, a study by University of California, San Francisco published in the Official Journal of the American Academy of Neurology examined the effectiveness of a vaporizer that heats cannabis to a temperature between 180°C (356°F) and 200°C (392°F) degrees and found:
Using CO as an indicator, there was virtually no exposure to harmful combustion products using the vaporizing device. Since it replicates smoking's efficiency at producing the desired THC effect using smaller amounts of the active ingredient as opposed to pill forms, this device has great potential for improving the therapeutic utility of THC.
In 2006, a study performed by researchers at Leiden University, tested a Volcano Vaporizer with preparations of pure THC and found that:
Our results show that a safe and effective cannabinoid delivery system seems to be available to patients. The final pulmonal uptake of THC is comparable to the smoking of cannabis, while avoiding the respiratory disadvantages of smoking.
When using plant material (crude flower tops), besides THC, several other cannabinoids as well as a range of other plant components including terpenoids were detected in the plant material. However, using pure THC in the Volcano Vaporizer, no degradation products (delta-8-THC (D8-THC), cannabinol (CBN), or unknown compounds) were detected by HPLC analysis. Also, a substantially larger fraction of the THC was delivered to the vapor by using pure THC.
Analysis of the vapor from the Volcano Vaporizer found that using multiple passes it delivered 36% - 61% of the THC in the sample. A more recent study using pure cannabinoid preparations achieved a maximum of 54%. For comparison, studies of cannabis cigarettes smoked via a smoking machine under varying conditions of puff duration and air speed found very similar efficiencies of 34% to 61%. Consequently, users can achieve the desired effect with a similar amount of material as when smoking.
In a 2001 study testing a device called the M1 Volatizer, the researchers found that "it is possible to vaporize medically active THC by heating marijuana to a temperature short of the point of combustion, thereby eliminating or substantially reducing harmful smoke toxins that are normally present in marijuana smoke." The M1 Volatizer, produced THC at a temperature of 185°C (365°F), while eliminating three measured combustion products, benzene, toluene and naphthalene. Carbon monoxide and smoke tars were also reduced, but not quantified.
These positive results are in contrast to MAPS/NORML's previous studies into vaporizers which found less encouraging results, leading one to the conclusion that the effectiveness of vaporization varies greatly from vaporizer to vaporizer. See Factors affecting vaporizer output for possible causes of variation.
A 1996 MAPS study tested two simple vaporizer models against water pipes and filtered and unfiltered cannabis cigarettes (joints). The smoke produced by each was analyzed for solid particulates (tars) and 3 major cannabinoids. The various smoking methods were then rated based on their cannabinoid-to-tar ratio. The two tested vaporizers performed up to 25% better than unfiltered cannabis cigarettes (second best) in terms of tar delivery. However, both vaporizers produced more than ten times more tars than cannabinoids, which may partly be attributable to the low potency (2.3%) of the NIDA-supplied cannabis used in the study. Surprisingly, the same study found that water pipes (bongs) and filtered cigarettes performed 30% worse than regular, unfiltered joints. The reason was that waterpipes and filters filter out psychoactive THC with the tars, thereby requiring users to smoke more to reach their desired effect. The study did not, however, rule out the possibility that waterpipes could have other benefits, such as filtering out harmful gases such as carbon monoxide.
These studies have not measured the presence of toxic gases, such as ammonia, hydrogen cyanide and carbon monoxide, though previous studies have indicated unquantified decreases in carbon monoxide with vaporization.
Although vaporizers produce cleaner vapors than smoking, they do not completely eliminate respiratory irritation. A puff of strong vaporized cannabis will occasionally cause coughing. This however, could be due to THC itself, which is known to have a strong expectorant effect.
The wide range of results from tests of different vaporizers suggest that the choice of vaporizer is a major factor in determining extraction and delivery efficiency as well as the amount of harmful byproducts produced, or not produced, as in the case of a superior system. In Cannabis and many other medicinal plants, the components responsible for the aromatic nature of the plant will often vaporize at a low-end temperature in the range of extraction temperature values for all the bioactive components. In Cannabis, the temperature range across which the actives will vaporize is at least 56°C (132°F) starting at around 127°C (260°F) where only aromatic compounds of minimal bioactivity will release and going all the way up to 200°C (392°F) with the higher end of this range representing where the cannabinoids of higher bioactivity appear to be released. It is believed that both the total amount of actives delivered as well as the breadth of spectrum delivered per inhalation is critical in determining the value of the delivered dose and, in turn, systems that deliver the highest amount of actives and broadest spectrum of actives per inhalation are believed to be the most effective for medicinal applications: i.e. venturi enhanced extraction / convection based systems.
Proposed factors affecting output include:
Not all those have been scientifically tested. Research using the vaporizer found the delivery efficiency highest at around 226°C (439°F), falling to about half efficiency at 150°C (302°F) to 180°C (356°F) degrees depending on material. The purest preparations produced the highest efficiencies, about 54% for pure THC versus 29% for plant material (female flower tops) with 12% THCA content. Besides THC, several other cannabinoids as well as a range of other plant components including terpenoids were detected in the plant material. Using pure THC in the Volcano Vaporizer, no degradation products (delta-8-THC (D8-THC), cannabinol (CBN), or unknown compounds were detected by HPLC analysis.
The longer vapor is stored, the more of the THC is lost as it condenses on the surface of the vaporizer or the balloon. This loss may be negligible over a few minutes but may exceed 50% after 90 minutes.
Interestingly, the Leiden Univsersity study found that as much as 30%–40% of inhaled THC was not absorbed by the lungs and simply exhaled. However, they did not find large individual differences in the amounts exhaled.
Unlike the black ashes produced by burning plants, the byproducts of vaporization are usually brown. Cannabis trichomes containing very high concentrations of active compounds burst during vaporization and appear flattened afterwards under a microscope. The vaporized remains of cannabis may still contain THC or any number of the other 60 cannabinoids found in the plant. It is possible to extract these cannabinoids using a number of methods, including cooking, making a tincture, or revaporizing. It is also possible to smoke these remains and gain a possibly strong psychoactive effect, but the negative health effects typically leave this option as a last resort. Some of the slang terms used to refer to the vaporized remains of cannabis include: Browns, Cached, Cashums, Coffee Grounds, Duff, Eva Brown, Floyd Tibbs, Gak, Mary Brown, No, Obama Browns, Post Roast, ReBurn, Revap, Snizap, Spent, Toasties, Vapor-leavin's, Vapoo, Vapor poo, Vented, Vapeweed, Vapedoof, Vaped Chron, Vaped Bud or Wheeler's Weed. When scraped off, the resin buildup within a vaporizer, known as Scrapings, can also be re-vaporized for a potent effect.
|Plant common name||Scientific name||Part utilized||Temperature|
|Eucalyptus|| ||Leaves||130°C (266°F)|
|Hops|| ||Cones||154°C (309°F)|
|Chamomile|| ||Flowers||190°C (374°F)|
|Lavender|| ||Leaves||130°C (266°F)|
|Lemon balm|| ||Leaves||142°C (288°F)|
|Sage|| ||Leaves||190°C (374°F)|
|Thyme|| ||Herb||190°C (374°F)|
|Cannabis|| ||Flowers||180°C (356°F)|