Understanding ultraviolet radiation

By Dr. Mariusz Sapijaszko

The sun - the source of energy for life on earth - also emits potentially dangerous rays that damage our skin

Ultraviolet light is essential to life on earth – but it can also kill. Emitted by the sun, ultraviolet light warms the earth, is used by plants to store energy as carbohydrate molecules (which also releases life-giving oxygen as a waste product) and enables our bodies to produce vitamin D, an essential mineral for our health. However, ultraviolet light also has a dark side, causing damage to our cells that can lead to premature skin aging and cancer.

Although we can’t see ultraviolet radiation, we can certainly feel it when we’re out in the sun and our skin tans or burns. Tanning is our body’s way of protecting itself from damaging radiation. When ultraviolet light strikes our skin, its energy is transferred to our cells. When the cells are damaged, they produce more of a protective pigment called melanin. However, if our cells can’t produce enough melanin, the result is a radiation burn, more commonly known as a sunburn.

The severe tissue damage caused by ultraviolet radiation leads to inflammation and an alteration in basic cell functions. Over time, this results in skin ageing, including skin thinning, skin fragility, abnormal pigmentation, sagging and wrinkles. It can also affect the functioning of our DNA, resulting in abnormal cell function, an inability to heal and cancer.

How our bodies respond to ultraviolet radiation varies from person to person and depends on many factors, including our genes, what we eat, what we apply to our skin and the medications that we take. 

The lighter our skin, eyes or hair colour, the more sensitive we are to ultraviolet radiation. Our skin can also become much more sensitive to the sun if we eat or are even in contact with certain foods, including limes, celery, carrots, figs, dandelions, parsnips or artichokes.

In addition, certain medications can make us more susceptible to the harmful effects of ultraviolet radiation. These include common heart medications (such as hydrochlorothiazide or amiodarone), anti-inflammatories (like ibuprofen), antibiotics (such as tetracyclines) and antidepressants (such as fluoxetine or St. John’s wort).

Ultraviolet radiation is a double-edged sword: needed for life on earth, yet deadly at the same time. We need to respect the sun’s power while taking precautions to minimize our individual risk from the damaging effects of exposure to ultraviolet radiation.   

Dr. Mariusz Sapijaszko is a nationally and internationally trained dermatologist and cosmetic surgery and laser surgery expert. He is a medical director of the Western Canada Dermatology Institute and Youthful Image Clinic, and as a clinical associate professor at the University of Alberta Division of Dermatology he is involved in training future dermatologists. 


The severe tissue damage caused by ultraviolet radiation leads to inflammation and an alteration in basic cell functions

UV radiation 101

Skin damage is caused by exposure to UVA and UVB radiation. Protect yourself by staying sun safe – use sunscreen daily, wear clothing that covers your skin and avoid peak hours of intense sun. 


  • 320 nm - 400 nm
  • not absorbed by the atmosphere
  • represents 95 per cent of ultraviolet radiation that reaches earth
  • present every day, all day, and is not affected by weather
  • penetrates deep into the skin, causing skin aging, tanning and cancer


  • 290 nm - 320 nm
  • much more powerful than UVA
  • represents 5 per cent of ultraviolet radiation that reaches earth
  • mostly absorbed by the atmosphere
  • helps us make vitamin D
  • responsible for tanning, sunburns, cancer and skin aging

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