Often gases are odourless and colourless. Of course, we have a few exceptions like Hydrogen Sulphide (H2S) and Ammonia (NH3). Ancient empires and their people tend to credit the phenomenon’s they can’t explain to their respective gods, like Zeus with his lighting. Since gases couldn’t be detected yet (and gas detection unfortunately wasn’t around) gas hazards were often credited to gods.
It's well known that Hydrogen Peroxide can be used for hair bleaching, but there are a lot of other uses as well.