Tea tree oil (TTO) is a popular essential oil extracted from the leaves of the Australian native plant Melaleuca alternifolia. It is widely used in topical applications and aromatherapy due to its antiseptic and anti-inflammatory properties. Because this concentrated oil is often stored in homes, understanding its physical properties, especially its potential for fire hazard, is a significant safety concern. The chemical nature of this concentrated plant extract means it requires careful handling.
The Flammability Classification
The concentrated nature of tea tree oil classifies it as a hazardous material under international standards. Essential oils are composed of volatile organic compounds (VOCs), meaning they evaporate readily at room temperature and release flammable vapors. Regulatory bodies, such as those following the Globally Harmonized System (GHS), classify tea tree oil as a Flammable Liquid, typically in Category 3.
This classification indicates the liquid itself does not need to be hot to pose a fire risk. Instead, the invisible vapors released from the surface ignite when mixed with air and exposed to an ignition source. Although some liquids are described as “combustible,” the consensus across safety data sheets is the designation “Flammable liquid and vapor” (H226), signaling a fire hazard.
Understanding the Flash Point
Tea tree oil is combustible due to its high concentration of monoterpenes and sesquiterpenes, which are volatile hydrocarbons. The primary component, terpinen-4-ol, along with compounds like gamma-terpinene and alpha-pinene, contributes to the oil’s rapid vaporization. The “flash point” is the lowest temperature at which a liquid produces enough vapor to form an ignitable mixture with the air above its surface.
For pure tea tree oil, the closed-cup flash point is reported to be in the range of 50°C to 57°C (122°F to 135°F). This temperature is easily reachable in non-climate-controlled environments, such as a car parked in the sun or near a heat source. Once this temperature is reached, a spark, open flame, or hot surface can cause the accumulated vapors to ignite.
Essential Safety Guidelines
Handling tea tree oil safely requires treating it like any other flammable solvent, keeping it away from all ignition sources. Store the oil in its original, tightly sealed container, preferably made of glass, in a cool, dark, and well-ventilated area. Direct sunlight and elevated temperatures must be avoided to prevent the oil from reaching its flash point and maintain its stability.
When using the oil, avoid spills and ensure adequate airflow to prevent the accumulation of flammable vapors. If a fire occurs, do not attempt to extinguish it with water, as the oil will float and spread the flames. Instead, use a carbon dioxide extinguisher, dry chemical extinguisher, or fire-fighting foam to smother the blaze. Materials soaked with the oil, such as rags, should be disposed of properly, as they represent a fire hazard and should not be left near heat.