Gas Mask the vision color doesn't change, I have done several training procedures with Gas masks, Night Vision and Thermal Imaging.
Gas mask: Clear vision but just have a slightly restricted view.
Night Vision: Generally is bright green shade, any lights should make it flare creating a bright white area/light green around the area of fire/Light/Heat.
Thermal Imaging: Generally a dark blue with reds,oranges and yellows for heat sources depending on where the infra red radiation would be the strongest. ( hottest area )
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