The gas pipes are buried in the ground, at a depth as provided under the law, and only in extreme situations there is a possibility for uncontrolled emission of natural gas in the atmosphere. Therefore, it is very important for the safety of the gas pipeline, the environment and the people, to observe the safety measures in the vicinity of the gas pipe. The biggest danger for the natural gas transmission pipeline system are the activities in the gas pipeline safety zone (construction and agricultural activities, effect from heavy-duty vehicles etc.) Due to such activities the term protective zone of the gas pipe was introduced in accordance with the Regulations for the technical requirements and norms for safe transport of liquid and gas hydrocarbons with national oil pipelines and gas pipelines and with oil pipelines and gas pipelines for international transport (Official Gazette 26/85). The natural gas is colorless, odorless and tasteless and for safety reasons odorant (aromatic substance) is added to it in order to feel its presence in concentrations below the lower limit of explosiveness.
If the natural gas is used properly it is harmless for man, animals and the environment. The malfunction of the gas devices, chimneys and the combustion air supply systems may lead to suffocation, intoxication or explosion.
The suffocation occurs with reduction of the oxygen concentration in the air.
The natural gas concentrations which are lower than 5% are harmless for the human organism, but the higher concentrations reduce the concentration of oxygen and lead to suffocation.
The intoxication may occur indirectly, in case of equipment malfunction and improper combustion of the natural gas and in such cases there is carbon monoxide in the smoke gas. The natural gas itself is not poisonous.
The natural gas belongs to the group of explosive gases, because it creates explosive mixtures in the air if its concentration in the mixture is higher than the determined minimum value, so called lower limit of explosiveness (Ld=5vol%), i.e. lower than the determined maximum value, so called upper limit of explosiveness (Lg=15vol%).
