For two days this week, ambulances will only attend incidents and emergencies in Wales where there is an "immediate risk to life". During this time, anyone else needing urgent medical care or that needs to go to hospital is advised to arrange to make their own way there.
This is because thousands of paramedics and other employees at the Welsh Ambulance Service are going on strike, in a dispute over pay and conditions. Around 1,500 Welsh Ambulance Service employees voted in favour of strike action last month - and their trade union, GMB, has arranged for its members and those at eight other UK ambulance services to walk out on December 21 and 28.
Whilst "emergency care is still a priority" and "emergency services will still be available," the Welsh Ambulance Service says, people are very likely to see delays and disruption to their care. Scroll down for more detail on how the strike could affect you and your family.