For fire to start, three things are needed : a source of ignition, a source of fuel and oxygen.
Examples of sources of ignition you may find on a construction site are:
Heaters; lighting; naked flames; electrical equipment; hot processes (such as welding or grinding); smokers’ materials (cigarettes, matches etc) and anything else that can get very hot or cause sparks.
Examples of sources of fuel you may find on a construction site are:
Flammable liquids (petrol, paint, varnish, white spirit etc); wood; paper; plastic; rubber or foam; liquefied petroleum gas (LPG); acetylene; loose packaging materials; waste rubbish; furniture.