A portable humidifier is an effective way to help you combat the effects of exposure to the harsh dry air while traveling on a plane or staying in a hotel room. Dry eyes, dry skin, nosebleeds, dry sinuses and cracked lips are all telltale signs that the humidity level in your environs could be low. Adding a fine cool mist of water to the air while you sleep with a mini humidifier can significantly remedy these symptoms, often overnight.