Lavender essential oil is a highly concentrated, volatile substance derived from the Lavandula angustifolia plant. Like many plant-based oils, this liquid contains organic chemical compounds capable of combustion. As a concentrated oil, it possesses inherent properties that make it a fire hazard under certain conditions. Understanding these characteristics is necessary for safe storage and use.
The Science of Ignition
The fundamental factor determining a liquid’s fire risk is its flash point. This is the lowest temperature at which a liquid produces enough vapor to form an ignitable mixture with air. It is the vapor, not the liquid itself, that actually catches fire. Lavender essential oil typically has a flash point ranging between \(149^\circ\text{F}\) and \(172^\circ\text{F}\) (\(65^\circ\text{C}\) to \(78^\circ\text{C}\)), though the exact figure varies based on the batch composition.
Since this temperature is significantly higher than standard room temperature, lavender oil does not spontaneously ignite under normal conditions. The oil must be heated to or above this flash point for the fire hazard to be present. Unlike highly flammable liquids like gasoline, which pose a risk at all times, lavender oil is classified as a combustible liquid. The liquid is also chemically stable.
Essential Safety Guidelines
Storing lavender oil requires specific precautions to prevent it from reaching its flash point. Containers must be kept away from all sources of ignition, including open flames, pilot lights, and electric heating elements. Avoid direct sunlight and storage near stoves or radiators, as heat accelerates the release of ignitable vapors. Oils should be stored in their original, tightly closed glass bottles.
When using the oil in diffusers, avoid overfilling the device or placing it near flammable materials. Rags or fabrics saturated with essential oils pose a risk of spontaneous combustion. These materials should be washed immediately or stored in an airtight, non-combustible container before disposal. If a spill occurs, use an inert absorbent material like sand or vermiculite for cleanup, rather than washing the oil down a drain with water.
Understanding Flammability Ratings
In a technical safety context, the terms “flammable” and “combustible” are distinct, based purely on the flash point temperature. Under National Fire Protection Association (NFPA) standards, a flammable liquid has a flash point below \(100^\circ\text{F}\) (\(37.8^\circ\text{C}\)). A combustible liquid, which includes lavender oil, is defined as having a flash point at or above \(100^\circ\text{F}\).
This classification system helps workers and consumers understand the relative risk of a substance. However, the Occupational Safety and Health Administration (OSHA) uses the Globally Harmonized System (GHS), which groups all liquids with a flash point below \(199.4^\circ\text{F}\) (\(93^\circ\text{C}\)) as “flammable.” This means that while lavender oil is a lower risk than highly volatile substances, it is still legally required to be handled with fire safety precautions. The key takeaway is that any liquid that can produce ignitable vapors requires careful storage and handling away from heat.