Overview for Aprilaire 600M Aprilaire humidifiers provide maximum comfort throughout your entire home - every hour, every day, all season long, without the mess and inconvenience of portables. Heating your indoor air dries out your skin. This not only makes you feel itchy but can also make you feel chilly. This cold effect is not the only discomfort caused by too dry air. Annoying static electricity is another indication of low humidity levels. Proper relative humidity (RH) will reduce this discomfort.