Petrol is a highly flammable liquid and gives off flammable vapour even at very low temperatures. When this vapour is mixed with air in proportions between 1% and 8% a risk of fire or explosion exists. Petrol vapour is heavier than air and does not disperse easily in still conditions. It tends to sink to the lowest possible level of its surroundings and may accumulate in tanks, cavities, drains, pits or other depressions.
Further information about safety issues and relevant contact details can be found by going to Licence - Petroleum and LPG, Liquefied Petroleum Gas (Petrol Storage and Filling Stations)