Air escaping when opening gas cap?

Everytime i open my cars gas cap i hear a hissing sound like air coming out when i take off the gas cap. Is that normal? I drive a 94 honda accord ex

Yes that is normal because evaporating fuel is a pollutant. So instead of the filler cap simply being vented, it traps pressure from fuel evaporation in the tank.

Yes, modern gas caps are air tight to slow down the amount of gas fumes that evaporate and escape into the environment. So it's normal for them to pressurise slightly and you get a "hiss" as you open them and let the pressure off.

Normal