First of all, gas is toxic, while natural gas is not (leakage leads to hypoxia).

Secondly, natural gas is very light and will soon drift upward in the air. Generally, as long as there is ventilation, it will spread in the shortest time, and gas is not enough. Gas and air almost have to have wind to flow.

Third, the current urban gas pipeline installation specifications are very strict. There must be no problem with the pipeline, and some joints may leak. Always pour some soapy water on the joints to see if there are bubbles. You can check them.

The natural gas pressure of the fourth household is very low. Moreover, natural gas has an odor, and leakage is easy to smell.