MONITORING PLACES OF DETENTION : A PRACTICAL GUIDE FOR NGOS 109 examine the case of each prisoner in order to ascertain whether specific security measures are really justified in his/her case. Further, even when such measures are required, they should never involve depriving the prisoners concerned of natural light and fresh air. The latter are basic elements of life which every prisoner is entitled to enjoy; moreover, the absence of these elements generates conditions favourable to the spread of diseases and in particular tuberculosis. The CPT recognises that the delivery of decent living conditions in penitentiary establishments can be very costly and improvements are hampered in many countries by lack of funds. However, removing devices blocking the windows of prisoner accommodation (and fitting, in those exceptional cases where this is necessary, alternative security devices of an appropriate design) should not involve considerable investment and, at the same time, would be of great benefit for all concerned.” CPT, GR 11, §30 Comments It is essential that detainees have access to natural light and fresh air. The windows must thus not be obstructed and it must be possible to open them. Detainees must be able to switch the lights inside the cell on and off themselves. 3