A lighting fixture assembly includes a housing assembly that forms an interior. A valve mechanism is associated with the housing assembly and is configured to automatically vent fluid from the interior to the atmosphere when the pressure in the interior exceeds a threshold level. Otherwise, the valve mechanism seals the interior from the atmosphere. The lighting fixture also includes a pressure-equalization mechanism, separate from the valve mechanism, which is also associated with the housing assembly. The pressure-equalization mechanism is configured to, upon activation, substantially equalize the interior pressure with the atmosphere pressure and to otherwise seal the interior from the atmosphere.