Physics Question #2853

Tracy, a 26 year old female from the Internet asks on July 25, 2005,

Why is a magnet classified as dangerous goods when shipping by air?

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The answer

James Livingston answered on July 28, 2005

A package containing a magnet would certainly not be "dangerous" in most cases. However, if it were a very large and very strong magnet so that substantial magnetic fields extended some distance from the package, and it was in close proximity to something containing magnetically coded data, such as ATM or credit cards, computer hard drives, memory chips, etc., it could cause some damage. If it were near some iron or steel, it could create an attractive force that could cause unexpected motion. (I was once shipped a magnet by UPS, and the delivery man complained that the small package containing it jumped up and stuck to the side of his truck.) People who have iron or steel in or on their bodies could be hurt by such motion. Motion of an iron or steel item within a package might also damage some sensitive devices. There are also concerns about the effects of magnetic fields on human health, although there are little data proving that such worries are justified for static magnetic fields.

Geoff Hilton, Director, Magnet Centre, University of Sunderland, UK answered on August 2, 2005

There is a set of IATA regulations for the transport of magnets by air. We carry out tests for clients called 'compass safe distance test'. This ensures that and magnetic materials are packed correctly and are shielded so that the magnetic fields emanating from the magnets do not interfere with navigational systems used on the aircraft.

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