Health and Harm: The Complexity of the Sun (Part 1)

Part 1 explores the basics behind sunlight & UV radiation. Part 1 also touches on the effects the sun has on our body… Stick around for Part 2, where I go into more detail about exposure, as well as how to get safe exposure!

Wholesome driver of optimal health, or cancer-inducing power to be feared?

The sun has been dreaded for years. Decades of rising skin cancer has led to health establishment warnings to avoid sun.

In contrast, health enthusiasts & influencers have started to embrace the sun. They promote a different theory. That it is fundamental to life on Earth and optimal human health.

Central to the debate is UV radiation, emitted by the sun.

So naturally we ask…who’s right? How does the sun impact our health? Is it healthy or dangerous?

Like most things, the truth is most likely somewhere in the middle. So lets get to it:

First, a Physics Lesson

The sun emits radiation which is shown on the electromagnetic spectrum. The electromagnetic spectrum defines all radiation known to man. This includes radio waves, Wi-Fi, visible light, & X-rays (among others).

The electromagnetic spectrum is distinguished by wavelength, which is inversely related to frequency. This means as the wavelength decreases, the frequency increases.

Frequency is generally correlated with “energy”. So a higher frequency equals higher energy. In this case, more energy also equals more danger.

You can see how wavelength and frequency relate below.

At the left most point is cosmic radiation, the highest energy and most dangerous to human life. At the right is radio waves and alternating currents, the most benign.

It’s worth noting you should be increasingly careful as you move left of visible light, up to the point of avoiding completely.

Where the Sun Comes In

The sun emits across most of the electromagnetic spectrum, some wavelengths more than others.

Our atmosphere filters out most of the dangerous, high energy radiation leaving us exposed to less harmful stuff.

Visible light makes it through. That much is obvious. We get a lot of infrared radiation from the sun as well as, and to a lesser extent, UV radiation.

Infrared and UV radiation are important to our health for different reasons. Unfortunately we tend to misunderstand UV radiation, and it drives excessive (but not completely irrational) fear.

What Should I Know About UV?

First, there are three major types of UV radiation: UVA, UVB, & UVC.

UV radiation is adjacent to visible light, specifically purple light. This is why UV bulbs tend to have a blueish-purple tinge.

It’s also a clue UV wavelengths are shorter than visible light. Again, this correlates to more energy.

UVA has the longest wavelength of the three. UVC has the shortest. For reference, UVC is adjacent to X-ray radiation.

The sun emits full-spectrum UV, however that doesn’t mean we’re exposed to all of it. Our ozone filters out a good chunk of UV radiation as we’ll discuss in more detail below.

UVA the Bronzer

UVA is the lowest energy version of UV radiation.

This wavelength of radiation passes through our atmosphere rather easy. So much so, roughly 95% of the UV radiation at Earth’s surface is UVA.

Not even windows and (to some extent) clouds will stop UVA. This means you’re exposed to UVA pretty much anytime sunlight touches your skin. To avoid it requires shade (clothing, trees, buildings, etc).

UVA penetrates to the dermis (second layer of our skin). It oxidizes our melanin, which darkens it & produces that nice tan we desire.

Burns and cancer are less likely from UVA (relative to other UV rays) due to it’s lower energy. That’s not to say it’s completely harmless. Burns and cancer can still happen, but its orders of magnitude more difficult than stronger UV rays.

It’s more likely UVA will damage skin and DNA in other, less life-threatening ways. The most common is premature ageing of the skin and deeper wrinkles.

UVB the Burner

UVB is next up in energy.

Fortunately the ozone filters out a higher percentage of this. UVB only makes up roughly 5% of the UV radiation at Earth’s surface.

This does vary on local conditions, more so than UVA. Weather for example, is a bigger factor. UVB does not easily pass through clouds. It also gets filtered out by objects like windows.

UVB only penetrates the surface layer of our skin and is responsible for sunburns. It is also responsible for most types of sun-related skin cancers.

On the flip side, UVB is required for Vitamin D production, so it’s a bit of a catch-22.

Tanning is a byproduct of UVB as well since it triggers melanin production. Melanin is produced in response as a defense mechanism to partially shield us from UV rays.

This is not instantaneous. Rather the melanin develops over a few days. It does however last longer than the bronzing you get from UVA.

The UVC You Can Ignore

UVC is the third and most energetic UV ray.

As mentioned, UVC brushes up against X-ray radiation. Take that as a clue this is not something to mess around with. Fortunately, we don’t have to worry about UVC exposure from the sun. Our ozone filters all of it out.

This is good news because UVC will do serious damage rather quick. You can end up with severe burns after minutes of exposure.

This does make UVC a fantastic germicidal. It damages the DNA of microorganisms and their ability to reproduce, effectively killing them off.

We use man-made UVC in various air & water applications (e.g. HVAC systems). It’s a great chemical-free disinfectant.

In Summary

UV radiation is important to understand so you know how the sun affects you. This is the first step to determining proper exposure.

The sun’s high energy radiation can potentially harm, yes, but it’s also a source of full spectrum radiation. This full spectrum radiation seems to have numerous, irreplaceable benefits.

The key is to take what you’ve just learned and apply that knowledge towards safe sun exposure.

This may fly in the face of some recommendations, but it is my opinion that we cannot simply avoid the sun and expect optimal health. There is a balance that must be struck.

In Part 2, we’ll explore exposure in more detail…

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Feature Image: Marion Wellmann from Pixabay

EM Spectrum: Horst Frank, CC BY-SA 3.0, via Wikimedia Commons