We just went through the case mates. Here are the cannons that are aimed at the river. The work down in the cannon rooms can be harmful as they are filled with smoke by the cannons and many soldiers inhale the smoke. Some faint or even die from smoke poisoning.

There are therefore chimneys that are placed above the cannons with the aim of clearing the cannon smoke as efficiently as possible. Another problem with the work in the cannon rooms is that the loud bangs from the cannons cause some of the crew to have hearing loss or even become deaf.