Every Day Is Special: ultraviolet light

Showing posts with label ultraviolet light. Show all posts

September 16 – International Day for the Preservation of the Ozone Layer

Posted on September 16, 2017

Do you know about the ozone layer?

This thin layer of gas protects our planet - well, let's face it, what I really mean to say is that it protects the living things on our planet - from the harmful parts of the Sun's radiation.

The Sun makes all of life on Earth possible - we count on it for
light and warmth and for the crucial starting energy of most food chains.

But the Sun also pours out more energetic forms of radiation that are
harmful to life. Ultraviolet radiation (UVR) causes sunburns and skin cancer,
and it is the ozone layer that generally protects us from the brunt of UVR.

In other words, the ozone layer protects people from speedy sunburns and elevated rates of skin cancer - but it also protects humans and indeed all of life!!! - from dying out!

It's been 30 years since the Montreal Protocol, an agreement made by 193 countries to outlaw certain human-made chemicals that were destroying the ozone layer. These chemicals, CFCs, were commonly used in aerosol spray cans.

When some scientists first pointed out the dangers of CFCs, some people pooh-poohed them. They thought it was more important to keep our spray cans than to think about some far-off danger that they weren't sure even existed.

Luckily, scientists kept working on the theory of the CFC danger, and by 1976, the U.S. National Academy of Science concluded that CFCs and other human-made chemicals posed a credible threat. A few countries, including the U.S., moved to ban CFCs in aerosol cans. By 1985, a hole in the ozone layer over Antarctica was discovered. And just two years later, nations met to discuss a larger, hopefully worldwide CFC ban - the Montreal Protocol I mentioned above.

The ban went into effect in 1989, and ozone levels stabilized in the mid-1990s and began to increase again in the 2000s. Recovery is hopefully going to continue, and scientists hope that even the Antarctic hole is going to close up by 2075.

Because of this success, some people call the Montreal Protocol the most successful international environmental agreement so far.

Let's do the same for climate change!!

Also on this date:

Mayflower Day

Biologist and activist Albert Szent-Gyorgyi's birthday

Stay Away from Seattle Day

Software Freedom Day

Third Saturday in September

Clean Up the World Weekend

Anne Bradstreet Day

Mexico's Independence Day (El Grito)

Glyndwr Day in Wales

Play-Doh Day

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June 27 – National Sunglasses Day

Posted on June 27, 2016

Sunglasses can be fun!

They are often very cool.

They can make our eyes more comfortable in glary places like beaches and sunlit snow fields. And they can make us safer when drivers can see the road, signs, pedestrians, and other cars better on sunny days – especially when the sun is low in sky.

But...sunglasses are good for your eyes?

The Vision Council is taking advantage of National Sunglasses Day to point out that sunglasses help protect our eyes from harmful UV light. Ultraviolet rays have been linked to such things as cataracts, macular degeneration, and other eye problems. Even the highest energy visible light may cause macular degeneration; this is called HEV (for High-Energy Visible) or blue light.

By the way, the very best way to protect your eyes (or to protect your identity, if you are famous and want to go unnoticed) is to wear a hat AND sunglasses. Also, wrap-around sunglasses protect more than the more typical open-sided styles.

Actress Meg Ryan avoids recognition with shades and hat...

Not all sunglasses are equal...

Of course you want a style you like and a fit that is comfortable, but you really should pay the most attention to the UV protection offered by sunglasses. Look for 100% UV protection labels (which sometimes are labeled UV 400). Those lenses will protect from both kinds of ultraviolet light.

Apparently a consumer-protection test was run on sunglasses; all of the expensive and moderate sunglasses labeled “100% UV protection” really did offer the protection. Most of the bargain-basement sunglasses with that label did, too – but at least one $5 pair did not. If you have any doubts, an optometrist can easily and quickly test your shades.

By the way, here are some sunglasses factors that have nothing to do with UV protection:

being polarized – this can help you see better but does not guarantee UV protection
being anti-glare – ditto the above
being a particular color or darker tint – there is no proof that particular colors of sunglasses (not even the amber “Blue Blocker” lenses), nor that darker-tinted sunglasses, do a better job of protecting your eyes than other colors or tints.

Kids' eyes need protection from UV radiation just as much as adults' eyes do!!

Modern or...?

Of course sunglasses with UV protection are pretty modern, but there were some early forms of eye protection invented over the course of history. Inuit people had to cope with a lot of sun-on-snow glare, and they often wore “glasses” made out of walrus ivory; they would view the world through narrow slits. The Roman emperor Nero watched gladiator fights through emeralds; I'm pretty sure he wasn't thinking of protecting his eyes from radiation! Another sort of early sunglasses was invented in 12^th Century China; these were flat panes of smoky quartz.

Inuit snow goggles

It wasn't until the 1900s that sunglasses were used by loads of people. They were first mass produced in 1929, and polarized lenses became available in 1936. Ray Ban invented anti-glare sunglasses for aviators during World War II, and his aviator-style shades also caught on with the general public.

Also on this date: