All hearing aid batteries are toxic and dangerous if swallowed. Keep all hearing aid batteries (and hearing aids) away from children and pets. If anyone swallows a hearing aid battery it is a medical emergency and the individual needs to see a physician immediately.
How long hearing aid batteries last
Typically hearing aid batteries last 5-14 days based on 16 hours per day use cycle. Generally, the smaller the battery size, the shorter the battery life. The sizes of hearing aid batteries are listed below along with their standard number and color codes.
Size 10: YELLOW
Size 13: ORANGE
Size 312: BROWN
Size 675: BLUE
Today's hearing aid batteries are "zinc-air." Because the batteries are air-activated, a factory-sealed sticker keeps them "inactive" until you remove the sticker. Once the sticker is removed from the back of the battery, oxygen in the air contacts the zinc within the battery, and the battery is "turned-on". Since many of today's automatic digital hearing aids do not have "off" switches, removing the battery from the hearing aid circuit by opening the battery door when not in use, assures the device is turned off.
Zinc-air hearing aid batteries have a "shelf life" of up to three years when stored in a cool, dry environment. Storing zinc-air hearing aid batteries in the refrigerator has no beneficial effect on their shelf life. In fact -- quite the opposite may happen. The cold air may actually form little water particles under the sticker. Water is made of oxygen and hydrogen. If the water vapor creeps under the sticker, oxygen may contact the zinc and the battery could be totally discharged by the time you peel off the sticker. Therefore, the best place to store batteries is in a cool dry place, like the back of your sock drawer, not the fridge.