What Are The Effects Of UV Light On The Skin?

Ultraviolet (UV) rays are among the many types of rays the sun emits. UV rays are however the most damaging.

Facilities such as phototherapy lamps as well as tanning beds and lamps are also common sources of artificial UV rays.

You have probably heard a thing or two about the dangers of exposure to UV light. But what really are the effects of UV light on the skin?

Read on to learn more about the implications of UV light for skin health.

Types of UV Rays

The two main types of UV rays that have effects on the skin are:

UVA Rays

Most controlled facilities such as tanning beds largely emit UVA rays. These rays accelerate the aging of skin cells and can cause extensive damage to the DNA of the skin cells.

UVA rays can also result in symptoms of skin damage such as wrinkles. More importantly, UVA rays can increase the risk of skin cancer due to the damage to the skin cell DNA.

UVB Rays

UVB rays are a little more intense than UVA rays and have a direct impact on the skin cells’ DNA. These rays can cause sunburns and prolonged exposure can increase the risk of skin cancer.

Although UVB rays tend to cause the most damage in terms of predisposing a person to different types of skin cancer, both UVA and UVB rays are equally harmful to skin health.

Factors Affecting UV Radiation Intensity

The intensity or amount of UV rays that reach your skin at any given time depends on several factors including:

Time of the day

As you might guess, UV rays are more intense during the day when the sun is high up. In particular, the hours between 10 am and 4 pm are the peak times for strong UV rays.


Summer and spring are the warmest seasons of the year and UV rays from the sun are the strongest at this time.


Those living closer to the equator are more exposed to strong UV rays than those living further away.

Weather conditions

It goes without saying that UV rays are strongest on sunny days in which there is little to no cloud cover. However, bear in mind that UV rays can be so intense that they penetrate the clouds.

UV Radiation Effects: Risk Factors

Several factors can increase a person’s risk for skin cancer.


The risk of skin cancer is higher among people who live in areas that experience bright sunlight much of the year or throughout the year.


If you frequently spend a prolonged amount of tie under the sun without adequate protection in the form of protective clothing and sunscreen, you can increase your risk for skin cancer.


If you have a history of sunburns due to overexposure to sunlight, you have a high risk of developing skin cancer later on.

Skin Type

While exposure to UV rays can affect anyone’s skin, people with light skin have a higher risk of developing skin cancer. However, it is not uncommon for people with darker skin to develop skin cancer.

People with naturally dark skin are less prone to skin cancer because their skin contains large amounts of melanin, which prevents harmful UV rays from penetrating the skin.

In addition to these factors, you are more prone to skin cancer if:

  • You have a family history of melanoma
  • You have many moles and freckles
  • You have autoimmune diseases such as lupus or systemic lupus erythematosus
  • You have medical conditions such as HIV, nevoid basal cell carcinoma syndrome
  • You take medicines that increase your sensitivity to sunlight or suppress your immune system

Harmful Effects Of UV Light

The effects of UV light can be chronic or acute. The acute effects of exposure to UV rays can resolve in the short term. Symptoms include tanning and sunburns.

On the other hand, the chronic effect of exposure to UVA or UVB rays can be adverse and even fatal. These include skin cancer, premature skin aging, immune system suppression, and severe damage to the eyes.

Acute Effects

The two most common acute effects of UV light on the skin are sunburn and tanning.


Also known as erythema, sunburn occurs due to an increased flow of blood to the skin when blood vessels dilate due to exposure to UV radiation. This typically results in reddening of the skin, painful blisters, peeling, and edema.

Exposure to UVB radiation is the main cause of sunburns but in areas with intense sunlight or during hot summer months, exposure to UVA rays can also contribute to the development of sunburns.

Redheads, blonde-haired people, and those with fair skin and freckles are more prone to sunburns. Even just a little exposure to the sun can cause sunburns in high-risk people.

Sunburns, which mostly affect the face, neck, and trunk area, can worsen 8-12 hours after exposure but the symptoms tend to clear out after a day or two.

Children and the elderly also face a high risk of developing sunburns when exposed to the sun.


Tanning, which is pigmentation of the skin’s melanin content, occurs due to direct exposure to the sun.

A tan becomes noticeable a day or two after exposure to the sun and may last for weeks or months.

Exposure to the sun increases the number of pigment cells in the skin, which leads to an increase in melanin in the skin.

For light-skinned people, the increase in melanin in the skin may seem to be beneficial but this amount of melanin is not enough to protect the skin from the harmful effects of UV rays.

In at-risk people, exposure to sunlight can cause thickening of the skin, a condition that can last for up to two months.

Chronic Effects

Premature aging of the skin and skin cancer are the most chronic effects of UV light on the skin.

Premature Aging

Overexposure to the sun can cause permanent structural damage to the skin. UVA radiation largely contributes to premature aging of the skin causing extensive damage to the elastin and collagen compounds found in the skin.

Common symptoms that can develop over a span of time include wrinkles, dryness, sagging, deep furrows in the skin, pigmentation, and loss of elasticity.

Skin Cancer

The most common types of skin cancer include melanoma, and non-melanoma skin cancers—basal carcinoma and squamous cell carcinoma.

Excessive exposure to UV light over the years can increase a person’s risk of developing non-melanoma cancer.

On the other hand, it is believed that irregular but intense exposure to UV light can increase the risk of melanoma.

Basal Cell Carcinoma

Majority of skin cancer cases are non-melanoma basal cell carcinomas. Basal cell carcinoma tumors usually do not metastasize and they grow slowly.

The tumors typically grow in areas that are exposed to the sun including the neck and head.

Age seems to play a role in increasing the risk of basal cell carcinoma with those aged over 50 years being more prone to this type of cancer.

Genetics may also contribute to the development of basal cell carcinoma in Caucasian individuals facing a higher risk.

People with inherited DNA defects and those with a suppressed immune system are also more likely to develop basal cell carcinoma.

Extensive exposure to the sun in childhood can increase the risk of developing this and other types of cancers.

Squamous Cell Carcinoma

Squamous cell carcinoma, a form of non-melanoma skin cancer is more prevalent among older adults and tends to affect men more than women.

This type of cancer is more potent than basal cell carcinoma, accounting for up to 75% of non-melanoma skin cancer.

The good news is that squamous cell carcinoma is readily treatable.

The most common sign of this skin cancer is the formation of lesions resulting from extensive exposure to the sun. The lesions have a keratin build-up, are red or the color of the skin, and have a rough texture.


Tumors causing melanoma skin cancers originate from the skin’s pigment cells. Because these tumors have a higher likelihood of metastasizing, melanoma skin cancers can cause death.

Young women are particularly at risk of developing melanoma cancers where the tumors tend to occur on the legs and back.

Older men are also at an increased risk with tumors typically developing on the upper back.

Intermittent exposure to UV radiation is enough to increase a person’s risk for skin cancer.

However, the occurrence of moles larger than 2 mm is the biggest risk factor for melanoma cancers.

The most common indication of melanoma is when these molds change color to become dark blue, gray, brown, red or, black. The moles may also begin to itch, form an irregular border, and cause pain.


Chronic exposure to the sun can drastically increase a person’s risk of developing skin cancer and other problems such as eye cataracts.

If you must go out in the sun, it is always recommended that you wear protective clothing and apply the right type of sunscreen to adequately protect your skin from the harmful effects of UVA and UVB radiation.