Natural Gas is a major issue because if levels become significant the smallest electro-static spark could inflict serious damage to anyone in the house or building.
Natural gas detectors are generally installed in kitchens because the primary source of a natural gas leak is a gas stove and oven. While you can smell gas, carbon monoxide is mixed in making it even more deadly because you think it is just a gas smell when the silent killer is attacking you and others. Also, if you aren’t home you want to be informed that this problem is occurring.