Control measures (1)

The HSE's first recommendation is to avoid entering confined spaces in the first place. Employers should check if the work could be done another way so that entry or work in confined spaces is avoided. In particular it may be possible to do the work from the outside using special equipment, for example the use of remote cameras for internal inspection of pipes or vessels.

If entry cannot be avoided employers must ensure a safe system for working inside the space. A risk assessment should help identify what precautions are necessary, depending upon the nature of the confined space. Everyone involved must be properly trained and instructed.

It is essential that a supervisor be appointed. They should be given responsibility to ensure that the necessary precautions are taken, to check safety at each stage and may need to remain present while work is underway, say the HSE.

The people carrying out the task must also be suitable for the type of work, in terms of both experience and training. Physical features and fitness plus any medical conditions must also be considered as the layout may place constraints upon movement within the confined space. A check should be made on the size of the entrance/exit. It may seem an obvious question to ask but 'is it big enough?' This is especially important if breathing apparatus is required within the confined space.

It may be necessary to increase the number of openings and improve ventilation. Mechanical ventilation may be necessary to ensure an adequate supply of fresh air. This is essential where portable gas cylinders and diesel-fuelled equipment are used inside the space because of the dangers from build-up of engine exhaust. The HSE further warns that carbon monoxide from the exhaust of petrol-fuelled engines is extremely dangerous and must never be used within confined spaces.

It may be necessary to test the air inside the confined space to make sure it is free from both toxic and flammable vapours and that it is fit to breathe. Testing should be carried out by a competent person using a suitable and correctly calibrated gas detector. Continuous monitoring may be necessary if a risk assessment indicates that conditions may change or simply as a further precaution.