Why has it taken the Government so long to come up with a face mask policy, and which ones work best?

All this week, the National Public Health Emergency Team (Nphet) has been discussing face masks in advance of Ireland moving to step one of a five-stage exit from lockdown come Monday.

Chief Medical Officer Dr Tony Holohan is expected to recommend we all start wearing masks while shopping in supermarkets, using public transport and perhaps in other situations too.

Will the Irish public get on board with this?

That remains to be seen. According to a recent opinion poll, 21pc of us already use masks, but only 28pc say we'll do so if the Government advises it.

However, Taoiseach Leo Varadkar has already promised there is no question of them actually being made compulsory.

Why has it taken so long for Ireland to come up with a mask policy?

According to the Taoiseach, it's because medical experts differ.

The World Health Organisation has been lukewarm about masks, claiming they're necessary only for people who actually have Covid-19 or are looking after coronavirus patients.

This is directly contradicted by the Euro- pean Centre for Disease Prevention and Control, which says masks can help healthy people too.

"It's not one of those straightforward decisions where science tells you what the right thing to do is," Mr Varadkar argued last month.

What's the case for face masks?

Put simply, supporters think they can stop the droplets caused by coughing or sneezing dead in their tracks.

Wearing a mask may not protect you, since particles flying through the air at high speed will often penetrate it.

The covering should, however, protect other people from your droplets if you're infected.

Since the symptoms of Covid-19 can take several days to appear, many scientists think it's common sense for everyone to use masks, whether they feel ill or not.

"You want the lockdown to finally end, don't you?" asked Trinity College professor of biochemistry Luke O'Neill in a recent article.

"Wear a face mask. Make a fashion statement. Wear one in your team colours. You'll be caring for others and, yes, the science says it all: face masks will hasten the end of this lockdown."

What about the arguments against?

Sceptics point out that there have been very few clinical trials involving masks and Covid-19, which means their value remains unproven. In fact, masks could even help to spread the virus if users fail to clean them properly or touch their faces afterwards.

Above all, there's a danger that masks may lull people into a false sense of security and cause them to neglect the basic precautions - washing their hands, wiping surfaces and staying two metres away from others.

Are all masks more or less the same?

No, they divide into three main categories.

Cloth masks are the most basic and can be made at home from old sheets or T-shirts.

Surgical masks contain non-woven fabric for added protection but must be used only once, making them environmentally unfriendly.

At the top end of the scale, N95 respirators are usually worn by doctors and nurses while carrying out difficult medical procedures.

The National Public Health Emergency Team (Nphet) is strongly encouraging us all to stick with cloth masks and leave the others for healthcare professionals who need them as a matter of urgency.

If I don't want to make my own mask, how easy is it to buy them?

It's about to become a lot easier. During the early days of Covid- 19, there were reports of price-gouging in areas where masks had almost sold out.

Now the market is being flooded, with Lidl offering them at cost price (€43.30 for a packet of 50) and companies such as Irish start-up Measc promising to manufacture tens of thousands at less than a euro each.

For the fashion-conscious, more stylish coverings are available from luxury brands including Prada and Gucci.

How does Ireland's mask policy compare with the rest of the world?

Essentially, we're playing catch-up. For several weeks now, masks have been almost universally worn across Asian countries with low infection rates, such as South Korea and Taiwan.

Europe is rapidly moving in that direction, with Germany, France and Spain all making them compulsory in public places. The UK has started advising people to wear masks in enclosed spaces, but not for exercising.

Over in the United States, things are a bit more confused. The country's Centres for Disease Control and Prevention recommends that Americans use masks, and they're mandatory for staffers in the White House, where two cases of Covid-19 have been confirmed.

President Donald Trump, however, is refusing to wear one, reportedly because he fears it would make him look ridiculous.

"Wearing a face mask as I greet presidents, prime ministers, dictators, kings, queens?" Trump said last month. "I just don't see it."

Could the formation of a new government make any difference to mask policy?

If anything, it might make them an even more central feature of Ireland's fight against this disease. Fianna Fail leader Micheal Martin, who's widely expected to become Taoi- seach within weeks, has expressed great en- thusiasm for masks, and recently discussed them with his sister-in-law in Singapore.

"She's been screaming at me metaphorically over the phone, 'Why aren't you guys wearing masks?'" he revealed this week.

Finally, will Ireland's introduction of face mask guidelines be a game-changer or is this mainly being done for optics?

Like so much else to do with this pandemic, it may be years before we know the full truth.

For now, the only certainty is that Covid-19 works like an invisible killer, and covering our faces is a powerful symbol of Ireland's determination to beat it.

Visit our Covid-19 vaccine dashboard for updates on the roll out of the vaccination program and the rate of Coronavirus cases Ireland