Natural gas is naturally colorless and odorless, thus making it quite impossible for people to realize when there is a gas leak. However, it has been quite a while since gas has been added scent in form of traces of mercaptan, so that people can smell it and take the necessary actions. You cannot miss the smell of gas, as it is not a pleasant one, more like the smell of rotten eggs. In case of emergency gas leaks, the recommendation is to evacuate the area as soon as possible.
Most countries have specific laws concerning gas line leaks (red tag), such as the Natural Gas Pipeline Safety Act, passed a few years ago in the United States, which requires that the providing companies should secure inspection services in case of emergency gas leaks in any environment that receives natural gas.
