Burning cigarette butts discarded by careless smokers can cause veld fires. But it’s unfair and irresponsible to believe that all unexplained veld fires are caused by smokers.
Fires caused by cigarettes can be placed into two categories. The first is where a person uses a burning cigarette with the specific intention of causing malicious damage, while the second is where a carelessly discarded burning cigarette butt starts a vegetation fire.
For a cigarette butt to start a vegetation fire, a certain set of conditions must be present, including:
- Length of the cigarette remaining: If smoked right down to the filter there will be very little combustible material remaining to start the fire.
- Wind strength: A suitable wind needs to be blowing that is neither too weak to keep the tip glowing, nor too strong that it extinguishes ember.
- Orientation of the cigarette butt to the wind : The cigarette needs to fall so that the burning tip faces the wind.
- Angle of the cigarette: The cigarette needs to land with the glowing tip at a downward angle.
- Type of vegetation it lands in: There is more chance of a fire starting in fine dry grass than in a pile of thick rubbery leaves.
- Temperature: The higher the temperature, the more chance of a fire. However, temperature normally drops when the wind increases, so both these factors need to be considered.
- Relative humidity (the amount of moisture in the air): This plays an important part as to whether a plant will catch alight.
- Amount of moisture in the vegetation: The more moisture present, the more difficult it is for vegetation to catch alight e.g. green plants burn less easily than dry vegetation.
People who smoke are asked not to discard their cigarette butts in an irresponsible manner.