Response tactics for outdoor leaks differ from those for indoor leaks, as gas leaks from outdoor sources may involve higher-pressure pipelines.

In addition to the distinctive, sulfur-like odor of mercaptan, look and listen for any of the following:

• The distinctive odor of natural gas

• A hissing, whistling or roaring sound

• Dead or dying vegetation (in an otherwise moist area) over or near a pipeline

• Continuous bubbling in water

• Dirt or water being thrown into the air

• An exposed pipeline after a fire, flood or other disaster

• A damaged connection to a gas appliance