MONITORING PLACES OF DETENTION : A PRACTICAL GUIDE FOR NGOS 120 All the premises used by or for the detainees must be kept permanently clean. In general, it is the detainees themselves who see to the upkeep of the premises. They should therefore be given the means and products necessary to carry out this task. 3 Reference points ■ Are the living quarters adequate as regards: ➤ the number of m2 per person? ➤ the number of hours that persons must spend in their cells (number of hours spent locked in over a 24-hour period)? ➤ ventilation and the amount of air available when the premises are closed? ➤ the planned length of detention? ■ Is maintenance material available?