40 26. Point of entry holding facilities have often been found to be inadequate, in particular for extended stays. More specifically, CPT delegations have on several occasions met persons held for days under makeshift conditions in airport lounges. It is axiomatic that such persons should be provided with suitable means for sleeping, granted access to their luggage and to suitably-equipped sanitary and washing facilities, and allowed to exercise in the open air on a daily basis. Further, access to food and, if necessary, medical care should be guaranteed. 27. In certain countries, CPT delegations have found immigration detainees held in police stations for prolonged periods (for weeks and, in certain cases, months), subject to mediocre material conditions of detention, deprived of any form of activity and on occasion obliged to share cells with criminal suspects. Such a situation is indefensible. The CPT recognises that, in the very nature of things, immigration detainees may have to spend some time in an ordinary police detention facility. However, conditions in police stations will frequently - if not invariably - be inadequate for prolonged periods of detention. Consequently, the period of time spent by immigration detainees in such establishments should be kept to the absolute minimum. 28. On occasion, CPT delegations have found immigration detainees held in prisons. Even if the actual conditions of detention for these persons in the establishments concerned are adequate -which has not always been the case - the CPT considers such an approach to be fundamentally flawed. A prison is by definition not a suitable place in which to detain someone who is neither convicted nor suspected of a criminal offence. Admittedly, in certain exceptional cases, it might be appropriate to hold an immigration detainee in a prison, because of a known potential for violence. Further, an immigration detainee in need of in-patient treatment might have to be accommodated temporarily in a prison health-care facility, in the event of no other secure hospital facility being available. However, such detainees should be held quite separately from prisoners, whether on remand or convicted.