When you open your car trunk, a light turns on to allow you to see inside. How does that happen? A switch containing liquid mercury signals that the trunk is up and turns the light on. (The mercury flows into a position where it completes the circuit so that the light comes on.) Now what happens to that mercury when the car is finally junked? Some of it can escape as the car is crushed. Then, what remains is melted down with the rest of the car body to make new steel and some of it goes up the smokestack and into the air.
But, now New Jersey has adopted a law that mandates removal of the switches from cars before they are crushed and melted down. Several other states have already done so or are thinking about doing so.
That's just the tip of the iceberg, however, since mercury switches are also found in irons, washing machines, deep freezers, space heaters, and other consumer items.
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