SMOKE VS. VAPOR
At least four scientific studies have examined vaporizers. Studies focusing on high-end vaporizer ranging in price from $149 to $600 have found the release of harmful constituents dramatically reduced or completely eliminated. However, a 1996 study including two simple vaporizers still found ten times more tar in the vapor than active ingredients , although this was nevertheless up to a 30% improvement compared to the best smoking method.
The most recent study (2006) , performed by researchers at Leiden University, tested the high-end Volcano vaporizer with preparations of popular smoking material and found that:
|"Our results show that with high end vaporizers a safe and effective herbal delivery system seems to be available to patients. The final pulmonal uptake of active ingredients is comparable to the smoking of them, while avoiding the respiratory disadvantages of smoking."
When using plant material (crude flower tops), several other active ingredients as well as a range of other plant components including terpenoids were detected in the plant material. However, using popular smoking herbs in the Volcano, no degradation products were detected by HPLC analysis. Also, a substantially larger fraction of the active ingredients were delivered to the vapor.
A 2004 study found that the aforementioned vaporizers were "remarkably clean", their vapor consisting of 89% active ingredients. In contrast over 111 different components appeared in the gas of the combusted smoke, including a half dozen known PAHs. Non-prefered compounds accounted for as much as 88% of the total gas content of the smoke. The study used popular plant material containing 4.15% active ingredients, and used Gas chromatography and mass spectrometry to analyze the vapor for a wide range of toxins, focusing on pyrene and other polynuclear aromatic hydrocarbons.
Analysis of the vapor from these vaporizers found that they delivered 36% - 61% of the active ingredients in the sample - a more recent study using pure herbal preparations achieved a maximum of 54% . For comparison, studies of herb 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 another device, the researchers found that "it is possible to vaporize medically active ingredient by heating herbs to a temperature short of the point of combustion, thereby eliminating or substantially reducing harmful smoke toxins that are normally present in smoke." The device produced active ingredients at a temperature of 365 degrees Fahrenheit (185 degrees Celsius), while completely eliminating three measured toxins, benzene, toluene and naphthalene. Carbon monoxide and smoke tars were also reduced, but not quantified.
These positive results are in contrast to 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 section 'Factors affecting vaporizer output' below for possible causes of variation.
A 1996 study tested two simple vaporizer models against common smoking devices and filtered and unfiltered herb cigarettes. The smoke produced by each was analyzed for solid particulates (tars) and 3 major active ingredients. The various smoking methods were then rated based on their active ingredient-to-tar ratio. The two tested vaporizers performed up to 25% better than unfiltered cigarettes (second best) in terms of tar delivery. Surprisingly, the same study found that filtered cigarettes performed 30% worse than regular, unfiltered ciagrettes. The reason was that filters filter out more active ingredients than they do tars.
As a word of caution, 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, it does not completely eliminate respiratory irritation. A puff of strong vaporized herb will occasionally cause coughing. This however, could be due to active ingredients themselves, which are known to irritate the bronchial tract.
Factors affecting vaporizer output
First of all, the wide range of results from tests of different vaporizers suggest that the choice of vaporizer is a major factor in determining delivery efficiency and the amount of harmful byproducts produced.
Proposed factors affecting output include:
- specimen density,
- weight, content of water and essential oils,
- consistency of material in the filling chamber
- different preparations such as crude flowertops, herbs , extracts & oil, etc.
- storage time of the vapor
- proportion of active ingredients exhaled (breathing technique)
Not all those have been scientifically tested. Research using the vaporizer found the delivery efficiency highest at around 226 degrees Celcius, falling to about half efficiency at 150 to 180 degrees depending on material. The purest preparations produced the highest efficiencies, about 54% for pure herb versus 29% for plant material ( flowertops) with 12% active ingredient content. Using pure herb in the Volcano, no degradation products or unknown compounds were detected by HPLC analysis.
The longer vapor is stored, the more of the active ingredient 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.
Common Vaporization Temperatures
LOW TEMPERATURE: up to (150C) 302F
Clove: (125C to 150C) 257F to 302F
Dandelion: (125C to 150C) 257F to 302F
Lavender: (100C to 125C) 212F to 257F
Meadowsweet: (100C to 150C) 212F to 302F
Passionflower: (100C to 150C) 212F to 302F
Peppermint: (100C to 150C) 212F to 302F
Sage: (125C to 150C) 257F to 302F
Saint Johns Wort: (100C to 150C) 212F to 302F
Thyme: (100C to 150C) 212F to 302F
Tobacco: (125C to 150C) 257F to 302F
MEDIUM TEMPERATURE: up to (175C) 347F
Cats Claw: (150C to 175C) 302F to 347F
Damiana: (150C to 175C) 302F to 347F
Fennel: (150C to 175C) 302F to 347F
Coffee: (150C to 175C) 302F to 347F
Ginkgo: (125C to 175C) 257F to 347F
Hawthorn: (125C to 175C) 257F to 347F
Saw Palmetto: (125C to 175C) 257F to 347F
HIGH TEMPERATURE: up to (200C) 392F
Aloe Vera: (175C to 200C) 347F to 392F
Evening Primrose: (150C to 200C) 302F to 392F
Garlic: (175C to 200C) 347F to 392F
Ginger (175C to 200C) 347F to 392F
Ginseng: (175C to 200C) 347F to 392F
Licorice: (175C to 200C) 347F to 392F