Bike Helmet Care
Do not use chemical solvents to clean a helmet. Manufacturers recommend only the use of a soft cloth or sponge, plus mild soap and water. Removable pads may be washed. Do not store a helmet in an attic, garage, car trunk or other area where heat can accumulate. Excessive heat may cause bubbles to form on helmet parts. Do not wear a heat-damaged helmet. Avoid loaning your helmet to others. You want to know exactly what kind of use your helmet has experienced during its lifespan.
When to Replace a Helmet Bike helmets are designed to absorb a single impact, so always assume that a helmet involved in any type of accident is damaged. Even if it looks OK, get a new one. Bike helmet does not have an expiration date, even if you've been crash-free, you should still replace any helmet after five years. Pollution, UV light and weathering may weaken key components over time.
source - rei.com
