system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it safer to turn off the engine/remove keys from the ignition when fueling a car?
gpt
Fuel emits a very flammable gas with a low ignition point. All you really need is a spark. On a windy day, when these fumes are dispersed quickly, it's generally ok. On a warm, humid, stagnant day, this can be very dangerous as your car is generating electrical energy while it runs which can easily spark enough to set off the gas.