Millions of people witnessed Danish footballer Christian Eriksen suffer a cardiac arrest at the European Championships last month.

It's a scene every football fan dreads.

Thankfully, the 29-year-old survived, and now questions over the importance of defibrillators are being asked across the world.

Fabrice Muamba is a former professional footballer. He also suffered a cardiac arrest during a match in 2012 and survived.

Like many others, Muamba saw the incident involving Eriksen live on TV and said it "brought back a lot of memories".

"It was very difficult to watch," he added.

"But I was just pleased he was able to come out of the pitch in a very positive circumstance, rather than the negative one."

Muamba says he and Eriksen are prime examples that anyone could suffer a sudden cardiac arrest.

In the UK, there are over 100k deaths recorded each year because of heart complications.

And with this in mind, campaigners like Muamba say that having a defibrillator at all levels of sport, not just the elite, is vital.

"We also have to channel that down to the lower league level to grassroots level so that if it happened in grassroots level somebody in there should be able to do CPR, somebody should be able to use a defibrillator they should have access to a defibrillator," he said.

It's estimated that there are around 10,000 publicly accessible defibrillators across the UK.

They are crucial to saving lives. Health experts say that using one five minutes after collapse could boost the chance of survival from 5 percent to 70 percent.

But a common misconception is that that they are hard to use or that a certain level of expertise is needed to use one.

Dr Andrew Deaner - a cardiologist who helped save Muamba's life - said that is not the case.

"You get one, you turn it on, it starts talking to you, it tells you where to put the pads that you need to put onto the patient's chest.

"It tells you what to do every step of the way. It will even tell you how to do the resuscitation part, so they're really easy to use."

The Premier League has vowed to donate 2,000 defibrillators to grassroots sports clubs.

But Muamba says there is still more to be done.

"When you go to every building, there's a fire extinguisher," he said.

"But I'm sure that not every building has a defibrillator in the building.

"So it's something that we hope the government will make mandatory."

He, along with other campaigners, hope that legislation will be introduced to ensure that defibrillators are always accessible at all sports grounds and more public spaces in the near future.