Irish people have not had that much call to use sunscreen over recent years thanks to the poxy pox that derailed so many of our travel plans so frequently between the spring of 2020 and, well, now.

Before anyone gets cross, that is not to say we have had no call to use sunscreen. There is no doubt that it is essential even in a country which is not frequently smiled upon by the sun god, and anyone who would even consider spending a lovely summer’s day in Ireland outdoors without putting on the stuff is, frankly, a bit thick.

And we say that having been that person far too many times over far too many years.

But with foreign travel now firmly back on the agenda — as the mad queues in airports across Europe clearly show — more Irish people will be spending more time in the serious sun this year than at any time since 2019 and could, maybe, do with a masterclass in the art of staying safe in the sun.

Which is better: spray, pump or bottle? How much do you actually need and how often should you apply it? Does waterproof really mean waterproof? Is the cheap-as-chips option in Aldi just as good as the madly expensive one in BTs? How long does a bottle last and how can you find out if it is still “fresh”? What do SPF, UVA and UVB mean and how the hell does sun cream work, and where on earth does it come from?

Can we start at the beginning? How long have people been using sun creams?

A lot longer than you might think. Anyone who was a child in Ireland as recently as the 1980s might believe sunscreen is an invention of recent years. There was certainly no sign of it being applied to Irish skin all that frequently until the 1990s. Before then, there were tanning oils that people would slather over themselves during the “peak tanning hours” between midday and 2pm to help the sun’s burning rays do their work (side note: these are not in fact the peak tanning hours, there is no such thing and those midday hours are the very ones in which you might consider not being in the sun at all). There was also calamine lotion which the same people would slather over themselves as night fell in order to soothe the pain of the sunburn.

But despite our woeful ignorance back in the day, sun blocks of sorts are not new. In fact the ancient Greeks were fond of an olive-oil-based potion which they used as sun protection. Mind you, the protection it offered was at best minimal because while the Greeks might have been wonderful at inventing philosophy and making a civil society, their science when it came to the sun was atrocious.

For starters, they thought sun damage was caused by heat. Yes, yes yes, that IS something Pricewatch could easily imagine thinking far more recently than the times before Christ. Now we know that the damage and the burning is caused by the ultraviolet spectrum. That discovery was made by scientists about 100 years ago, with the first synthetic sunscreen hitting the market 92 years ago.

How does sunscreen work anyway?

Well, without getting into too much complex detail — something that would surely expose our ignorance on the topic to rays of fury more burning than the midday sun — the creams or oils either block the sun from reaching our skin to the same extent that it otherwise might by using compounds such as zinc to scatter light. Alternatively, chemicals can be deployed to absorb the UV light so our skin doesn’t have to.

And is all ultraviolet light the same?

Nope. There are two types we are concerned by when it comes to sun blocks: UVA and UVB. UVA ages the skin while UVB does the burning.

And speaking of three letter combos, what is SPF and where did it come from?

Sun protection factor (SPF) as a notion was the brainchild of Swiss chemist Franz Greiter. He had a particular interest in the topic of sunburn, having once turned a painful shade of lobster red while on the Swiss mountain of Piz Buin. He called his sun cream after the mountain and it is still one of the most popular sun creams on the market.

So, what does SPF mean?

It measures a sunscreen’s ability to prevent UVB from damaging your skin. If it takes 20 minutes for your unprotected skin to start going red, an SPF of 15 sunscreen should stop you burning for 15 times 20 minutes, or about five hours. SPFs can also be viewed through a percentage prism. So 15 filters out 93 per cent of UVB, 30 keeps out 97 per cent and SPF 50 keeps out 98 per cent. Incidentally Greither’s first standardised sun cream had an SPF of 2.

So, all I need to consider is the SPF?

Ah no. SPF is only half the story when it comes to protection. While it lessens the damage done by UVB radiation, it does little to stop harmful UVA radiation. For that you have to look to the star rating. A one-star cream offers “minimum” protection while five-star cream provides “ultra” cover.

So, if I slather myself in SPF 50 in the morning am I good to go all day?

Sadly, that is not how it works. The protection most sun creams offer starts to wane after roughly the same amount of time but the higher SPFs block more of the sunlight. You should really consider applying sunscreen every two hours and immediately after swimming or sweating.

But my sun cream is waterproof so I’m grand, right?

No. No sunscreen is ever really waterproof, although some are more water resistant than others.

Do I need to know anything about how to apply it?

Just lash it on to you is the best tip we can give. It is also important to apply sun cream 20 minutes before going into the sun as that gives it time to bond with the skin. And when it comes to how much to put on the answer is almost certainly more than you think. Repeated studies over many years have shown that most of us apply only 20-50 per cent of the recommended amount of sunscreen and get a lot less protection than we think. It should be applied thickly and evenly, with an amount about the size of a golf ball in your hand for use over your entire body. A better way of looking at it might be teaspoons. You should apply a teaspoon for the face, each arm, each leg, the front of the body and the back. You will probably end up using 35ml of sun cream for your whole body.

And how much do I need to spend?

If you apply the right amount at the right intervals using a fairly well-known brand, an average-sized adult will probably have to spend about €35 over the course of a week. If you use an expensive brand found in a high-end department store, the same coverage will cost closer to €100 while if you go own-brand and stock up in Aldi, Lidl or Tesco, a seven-day supply will cost no more than €15.

But if I spend more I will get a better product, right?

Nope. When it comes to sun creams, the price you pay isn’t really an indicator of quality — at least in terms of pure protection. Truth be told, the more you spend the more you are likely to use it sparingly and the more sparingly you use it, the less protection you will get. British consumer group Which? frequently tests sunscreens and has repeatedly said good things about much cheaper own-brand options while some high priced alternatives have been found wanting. That is not to say all products are identical and some of the more expensive options do smell nicer and go on much easier.

Is the bottle I bought last year and barely used, because, you know, staycations and all that, still safe to use?

There is an easy way to check. There should be an icon of small jar and a number — 3, 6, 12 — followed by an M on the label somewhere. That indicates just how many months after opening a product will last. But given that your sun cream was probably in the sun, and heat damages chemicals, it might not last as long as it says, so you may as well chuck last year’s bottles before you go into the sun this year.

Am I better of buying all my sunscreen when I travel overseas?

That depends on where you are going and where you are buying. The German discounters here have great value sun creams and may not be easy to find on the beach in Marbella. Boots has great value sun creams, particularly when the ranges are on special. Sun creams in France are expensive, much the same price as here in Italy and cheaper in Spain, although the closer you get to the beach resorts there, the higher the prices.