Prison overcrowding is one of the key contributing factors to poor prison conditions around the world. It is arguably the biggest single problem facing prison systems; its consequences can be life-threatening at worst and at best prevent prisons from fulfilling their proper function. Data from 2016 suggest that the number of prisoners exceeded official prison capacity in at least 115 countries, while as many as 51 countries had a problem of extreme overcrowding (above 150 per cent of capacity).
The overuse of solitary confinement in prisons around the world is becoming an increasing concern. Some form of short-term isolation from the rest of the prison population is used almost everywhere as punishment for breaches of prison discipline. However, many states increasingly use solitary confinement routinely and for longer periods of time. In the United States, for example, it is estimated that 80,000 individuals are being held in some form of isolation.
States have an obligation to protect the lives and well-being of people in custody. States also have an obligation – in line with the prohibition on ill-treatment and the right to health – to ensure hygiene and adequate healthcare in prisons. Poor sanitary conditions, inadequate lighting and ventilation, extremes of temperature, insect and rodent infestation and insufficient or non-existent personal hygiene supplies all have a negative impact on prisoners’ health.
Rates of infectious disease, notably HIV/AIDS and TB, are much higher in prisons than in the rest of the population in most countries. UNAIDS estimates that prisoners are five times more likely to be living with HIV. Notification rates for TB in European prisons ranges between 11 and 81 times higher than in the general population (WHO).