“Sorry it carbon monoxide not C02. A gas leak can cause that”
Gas leaks do not produce CO.
Gas leaks can kill by displacing the oxygen in the air, causing asphyxiation, or by releasing toxic gases like carbon monoxide which bind to the blood, preventing it from carrying oxygen, ultimately leading to death; both scenarios can happen when a gas leak builds up in a confined space, making it difficult to detect due to the odorless nature of the gas.
From a quick google search