- 16 3. Conditions of detention a. introduction 23. In the course of its previous visits, the CPT found that, in general, conditions of detention in police establishments were not satisfactory5. In certain cases, the CPT characterised the situation observed as amounting to inhuman and/or degrading treatment; this was particularly - but not only the case as regards immigration detainees, who were often subjected for prolonged periods to a combination of negative factors (overcrowding, very poor material conditions and levels of hygiene, lack of outdoor exercise, absence of any activities) (cf. for example, CPT/Inf (2001) 18, Part II, paragraphs 11, 16 and 33).6 The CPT has made a large number of recommendations aimed at improving conditions of detention in police establishments, both generally and in respect of the specific establishments visited.7 The 2001 visit provided an opportunity to assess developments in this connection. b. situation in the establishments visited i. police headquarters and stations 24. The detention facilities in these establishments are designed to hold criminal suspects for short periods. It should be noted, however, that such facilities are in practice frequently used for holding persons for prolonged periods, in particular immigration detainees. Conditions were, on the whole, good for short periods of detention at Athens Airport and Heraklion Airport Police Stations, as well as at the Customs authority detention facility at Kristalopigi; they were also quite satisfactory at Kastoria Police Headquarters and at Agia Varvara, Agios Myronas, Myres and Nikea Police Stations. In those establishments, cells had adequate artificial lighting and ventilation and, in certain cases, had some access to natural light; they were clean and in a reasonable state of repair. Sleeping arrangements consisted of plinths or beds and, in most cases, the delegation observed that clean mattress and blankets were available to detainees. 5 The general criteria employed by the CPT when assessing material conditions of detention in law enforcement agency establishments were spelt out in CPT/Inf (94) 20, paragraph 52 and CPT/Inf (2001) 18, Part I, paragraph 20, and the specific requirements for immigration detention centres in CPT/Inf (2001) 18, Part I, paragraph 73 and CPT/Inf (2001) 18, Part II, paragraph 35 (cf. also, paragraphs 36 to 39 of this report). 6 Cf. also in this connection, the judgement of the European Court of Human Rights in the case of Dougoz v. Greece. 7 Cf. inter alia CPT/Inf (94) 20, paragraph 88, CPT/Inf (2001) 18, Part I, paragraphs 44 and 46, and CPT/Inf (2001) 18, Part I, paragraph 45 and Part II, paragraph 40.