Who will pay for the gas leak?

If it's not in your house, you shouldn't be responsible for the air leak. Because you can't control the pipeline outside your home, of course, the natural gas company will bear it, or if they entrust property management, the property is also responsible. But generally speaking, the maintenance of this highly professional thing is carried out by their own company, and other companies are not professional. So, if something goes wrong, of course, he will bear it himself.