Evaporative and misting coolers use water to reduce air temperatures for cooling people and equipment. They have no refrigerant to recharge and typically cost less to operate than refrigerant-based air conditioners. Evaporative coolers pull in warm air, pass it through wet media (evaporative pads) to remove heat, and blow out the cooled air. Also called swamp coolers, they are most effective in drier climates where the dew point is less than 50°F. Misting coolers generate an atomized mist of water that quickly evaporates to cool surrounding air. They have no evaporative pads to clean or change out.