'Laughing gas' stolen from Prince Charles Hospital
Cylinders of nitrous oxide - also known as laughing gas - were stolen from a hospital.
The anaesthetic gas is used for pain relief in dentistry and childbirth but can also create a euphoric feeling if inhaled recreationally.
A number of 4ft cylinders were taken from Prince Charles Hospital, Merthyr Tydfil, in the early hours of Sunday.
South Wales Police warned people against buying them, saying they could be dangerous.
Cwm Taf Morgannwg health board, which runs the hospital, said thieves cut chains from gates and entered the estates department where the cylinders were stored.
"Nitrous oxide can be extremely dangerous to the public," a spokesman added.
Empty silver canisters of the gas have become a common sight outside nightclubs, with it most commonly inhaled from balloons.
Legislation introduced in 2016 made it illegal to sell the gas, also known as "noz", for recreational purposes.
But its supply is difficult to control because it has legal uses, such as to produce whipped cream in the catering industry, and in medicine as an anaesthetic.
Police believe a vehicle was used to take the cylinders from Prince Charles Hospital.
- Effects: Feelings of euphoria, relaxation and calmness, dizziness, difficulty in thinking straight and fits of giggles/laughter, sound distortions or even hallucinations
- Risks: If gas is consumed in an enclosed space or if a plastic bag is used, it may cause lack of oxygen; heavy regular use can lead to severe vitamin B12 deficiency and anaemia; it may also depress formation of white blood cells
- If someone collapses after using nitrous oxide, call an ambulance immediately, turn them on to their side to avoid choking and stay with them until the ambulance arrives