Oregano, or Origanum vulgare, is a flavorful culinary herb belonging to the mint family, Lamiaceae. While its aromatic leaves are commonly used fresh or dried in cooking, some questions arise about the physiological effects of using the plant in non-traditional ways, such as smoking. Understanding this practice requires examining the plant’s chemistry and the universal consequences of inhaling combustion products.
Key Chemical Components of Oregano
The volatile essential oils of oregano contain phenolic compounds, primarily carvacrol and its isomer, thymol. These two compounds form the most biologically active portion of the oils and can account for a substantial percentage of the plant’s essential oil content, with carvacrol concentrations reaching over 75%.
In their natural state, these components have beneficial properties, including potent antimicrobial and antioxidant activity. When ingested or used topically, carvacrol and thymol are safe, contributing to the herb’s traditional use. This chemistry changes drastically when the plant material is exposed to intense heat rather than being consumed.
General Hazards of Inhaling Combusted Plant Matter
Inhaling smoke from any burning plant material, including oregano, subjects the respiratory system to hazards created by pyrolysis, the chemical decomposition caused by high temperatures. The primary danger is the generation of fine particulate matter (PM2.5), which consists of microscopic solids and liquid droplets. These particles bypass the body’s natural defenses, penetrating deep into the lungs and entering the bloodstream.
Combustion also produces gaseous toxins, most notably carbon monoxide, which interferes with the blood’s ability to transport oxygen. Other byproducts include polycyclic aromatic hydrocarbons (PAHs), nitrogen dioxide, and various tars. Inhalation of these products is directly linked to irritation of the throat and lungs, chronic inflammation, and long-term respiratory and cardiovascular damage.
Health Impact of Heating Oregano’s Active Ingredients
The health impact of smoking oregano stems from the thermal decomposition of its high concentration of carvacrol and thymol. These phenolic compounds are unstable when exposed to heat, with degradation beginning around 140°C to 190°C, well below combustion temperatures. Subjecting them to high heat causes their chemical structure to break down into new, more irritating breakdown products.
This thermal alteration results in the formation of various volatile organic compounds (VOCs), including aldehydes and ketones. Aldehydes are known respiratory irritants commonly produced from the pyrolysis of organic material. Inhaling these thermally altered oregano compounds leads to an acute, burning sensation in the mucous membranes of the nose, throat, and lungs, characterized by excessive coughing and inflammation.