Gasoline Safety
High Risk Areas for Gasoline Vapor Ignition
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§Basements and Closed Garages
§     - Most likely areas for gasoline storage and use
§   -  May have little air movement
–      -  May contain ignition sources    
 High Risk Areas for Gasoline Vapor Explosion

Basements and closed garages are the household areas where gasoline vapor ignition is most likely to occur. Think of them as small engine compartments, just waiting to explode when someone handles gasoline carelessly or uses it for a purpose it was never meant to serve.
They are the areas where any gasoline in the house is most likely to be stored, and used for a purpose for which it was not intended.
They likely have little air movement.
And they may be contain several potential ignition sources.

(Bridge)  What are those potential ignition sources?