The Channel Tunnel will soon be open and millions of people are expected to use it. But are there any health risks associated with travelling through the tunnel? Eurotunnel have recently issued guidelines for doctors (available from Eurotunnel*, and these have focused on the effects of such travel on the ears.

Everyone experiences some slight discomfort when entering a tunnel in a train or when flying. Rapid changes in ambient pressure occur when entering a tunnel at speed, or when two trains pass each other in a tunnel. This increase in pressure deflects the intact tympanic membrane medially.

The tympanic membrane is, of course, designed to move, and most people can equalise the relative pressures each side …