Use your CGI to monitor the air around the building.
If gas concentrations are well below the lower explosive limit of 5 percent gas and you can enter the building without risk, check for natural gas in the following locations:
- The areas where any underground water, sewer, electric or drain lines enter the building.
- The regulator, meter bar and all piping that supplies natural gas, as well as the piping around all gas-fired appliances, such as water heaters and clothes dryers.
- The spot where the gas service enters the building.
- Any cracks in the wall.
- All high points in the ceiling where natural gas could collect.