UV indices: understanding what they mean and protecting your skin effectively

To fully understand the role of the UV index, let’s first take a look at the different types of ultraviolet radiation emitted by the sun.

What is ultraviolet radiation?

The sun emits visible light and heat, but also ultraviolet rays, also known as UV.

There are three main categories of UV rays, classified according to their wavelength: UVA, UVB and UVC. Each has specific characteristics and does not affect the skin in the same way.

• UVA: these account for around 95 per cent of the ultraviolet rays that reach the Earth’s surface. Their wavelength ranges from 320 to 400 nanometres (nm). They easily pass through clouds and glass and penetrate deep into the skin. UVA rays contribute to premature skin ageing, loss of skin elasticity, and the appearance of wrinkles and pigmentation spots. They indirectly contribute to the development of skin cancers

• UVB rays: their wavelength ranges from 280 to 320 nm. They mainly affect the superficial layers of the skin. UVB rays are responsible for sunburn and can cause cellular damage as well as DNA alterations. However, they also play a key role in the body’s synthesis of vitamin D with moderate exposure

• UVC rays: their wavelength ranges from 100 to 280 nm. As they are highly energetic, they are almost entirely absorbed by the ozone layer and the Earth’s atmosphere. They therefore generally do not reach the Earth’s surface and do not pose a risk under natural exposure conditions.

This distinction is important, as both UVA and UVB rays can affect the skin, but their effects and mechanisms of action differ. Effective sun protection must therefore provide protection against both types of radiation.

So, what is the UV index?

The UV index is an international scale used to assess the intensity of ultraviolet radiation emitted by the sun at a specific location and time. It also indicates the level of risk associated with this exposure to the skin and eyes. The higher the index, the greater the UV intensity and the more vigilant you need to be.

This index varies depending on several environmental factors:

• The time of day: UV radiation reaches its peak around midday, when the sun is at its highest in the sky

• The season: UV indices are generally higher in spring and peak in summer

• Altitude: the higher the altitude, the less effectively the atmosphere filters out UV radiation. It is estimated that at an altitude of 1,000 metres, the intensity of radiation increases by around 10 per cent

• Latitude: regions close to the equator receive more intense UV radiation throughout the year, due to the rays having a shorter path through the atmosphere

• Reflection: certain surfaces such as water, sand or snow reflect some of the UV rays, which increases their impact on the skin

• Cloud cover and ozone: Clouds can partially attenuate radiation, but a significant proportion of UV rays still pass through the atmosphere. The thickness of the ozone layer also acts as a natural filter.

The UV index does not necessarily correlate to the temperature. It is entirely possible to have a cool day with a high UV index, which makes monitoring it particularly important for adapting your protective measures.

Contrary to popular belief, the UV index does not indicate your ability to tan. Its purpose is to measure the intensity of ultraviolet radiation and the risks associated with it.

When exposed to UV rays, the skin activates various defence mechanisms. These include, notably, the production of melanin, the pigment responsible for the skin’s natural colour. This phenomenon is primarily a protective reaction to external stress. UV rays can contribute to the development of pigmentation spots, accelerate skin ageing and gradually damage skin cells.

As soon as the UV index reaches 3, it is recommended that appropriate protective measures be taken.

This classification provides a simple guide to helping you adapt your daily routine and protect your skin from the cumulative effects of ultraviolet rays.

Good to know: in certain mountainous regions or areas close to the equator, the UV index may, in exceptional cases, exceed level 11.

When the UV index reaches 3 or higher, there are several additional measures you can take to effectively reduce the exposure of your skin and eyes to ultraviolet radiation.

Choose shaded areas

Shade remains one of the most effective ways to reduce your exposure to UV rays. Under a tree, a parasol or a shelter, the intensity of solar radiation is generally lower, although some UV rays are still present.

Wear clothing that covers your skin

Clothing acts as a physical barrier against UV rays. Long sleeves, wide-brimmed hats and special UV-protective clothing offer particularly effective protection on very sunny days.

Avoid the hottest hours of the day

UV rays generally reach their peak intensity between 12 noon and 4 pm in Europe. Where possible, it is best to enjoy outdoor activities in the early morning or late afternoon.

Protecting your eyes

UV rays can also affect the eyes. Wearing sunglasses that comply with current standards for UV protection helps to limit these effects, particularly near reflective surfaces such as water, sand or snow.

Use sun protection when the UV index is 3 or higher

When physical protection measures are insufficient or difficult to implement, a suitable suncare product can provide additional protection for the skin. It is important to apply a sufficient amount of the product to all exposed areas and to reapply it regularly, particularly after swimming or if you have been sweating heavily.

Support your skin with antioxidants

UV rays promote the production of free radicals, which are responsible for a phenomenon known as oxidative stress. Certain antioxidant active ingredients, such as Vitamin C or astaxanthin, help to protect cells against this phenomenon and to preserve the skin’s radiance.

The UV index and SPF are often confused, even though they are two completely distinct concepts.

• The UV index measures the intensity of ultraviolet radiation present in the environment at any given time. It enables you to assess the level of risk associated with the sun and to adapt your protective measures

• SPF (Sun Protection Factor), also known as the sun protection factor, indicates the level of protection provided by a suncare product against UVB rays, which are the main cause of sunburn.

SPF ratings are divided into several categories:

The higher the SPF, the more UVB rays the suncare product filters out before they reach the skin. However, no suncare product blocks 100 per cent of ultraviolet rays.

SPF alone is not sufficient to assess a product’s overall level of protection. For optimal protection, it is best to choose a suncare product that offers broad-spectrum protection against UVA and UVB rays.

Furthermore, the effectiveness of a suncare product depends on several factors:

• The amount of product applied

• How often the product is reapplied

• The intensity of the UV index

• Sweating

• Swimming

• Rubbing caused by clothing or towels.

This is why it is recommended to reapply sun cream regularly, particularly after swimming, even when the product is advertised as water-resistant.

Finally, it is important to bear in mind that SPF is only one aspect of sun protection. Seeking out shaded areas, wearing protective clothing, a hat and sunglasses remain essential when the UV index reaches 3 or higher.

Protecting yourself from UV rays is very important, but when choosing a suncare product, you should also consider its impact on the environment. Some of the sun filters applied to the skin are released into the water while swimming and end up in aquatic environments. It is therefore important to ensure that the filters used have a limited environmental impact and are released in small quantities into the aquatic environment.

All sunscreens have an environmental impact to varying degrees. The challenge is therefore to prioritise those whose effects on marine ecosystems – particularly coral reefs – are the least damaging. More and more consumers are looking for formulations that provide effective protection against UV rays while minimising their environmental impact.

To choose the right suncare product, there are several criteria to take into account: broad-spectrum protection against UVA and UVB rays, an SPF suitable for the conditions of exposure, good water resistance where necessary to help the product stay on the skin and limit its dispersion into the aquatic environment, and the nature of the sun filters used.

Sun filters are the ingredients that help limit the amount of ultraviolet rays reaching the skin. There are two main categories:

• Organic filters: these absorb some of the UV rays before they penetrate the skin

• Mineral filters: these act mainly on the skin’s surface by reflecting and scattering some of the ultraviolet radiation.

Among these mineral filters, zinc oxide is particularly valued for its broad-spectrum protection against UVA and UVB rays. It is notably used in many formulations designed for people wishing to combine sun protection with a commitment to the environment.

With this in mind, our suncare products are formulated with zinc oxide, a 100% naturally derived mineral filter. Certified organic and dermatologically tested, our formulations have been developed to ensure effective protection that meets rigorous quality and safety standards, while minimising their impact on the environment.

When the UV index reaches 3 or higher, physical protection remains a priority: seek shade, wear covering clothing and limit activities during the hottest hours of the day. Suncare products can then complement this protection to help the skin cope with ultraviolet radiation.

Mineral Sun Milk SPF 20

This SPF 20 mineral sun milk protects the skin from UVA and UVB rays thanks to a mineral filter based on 100% naturally sourced zinc oxide. Its certified organic formula also combines Pongamol and organic passion fruit oil, both of which have antioxidant properties. Water-resistant, it is suitable for the face and body from the age of 3. Its lightweight texture with an invisible finish leaves the skin feeling soft, without any stickiness or white residue.

Discover the SPF 20 mineral sun milk

Mineral Sun Milk SPF 30

Formulated with a 100% naturally derived mineral filter based on zinc oxide, this SPF 30 sun milk helps to effectively protect the skin against UVA and UVB rays. Its milky texture glides easily onto the face and body, leaving no white residue or sticky feeling. Water-resistant, certified organic and dermatologically tested, it is suitable for the whole family from the age of 3.

Discover the SPF 30 mineral sun milk

Mineral Sun Balm SPF 50

This SPF 50 sun balm combines high UVA and UVB protection with a melt-in, comfortable texture. Its certified organic formula is based on a 100% zinc oxide mineral filter, enriched with organic passion fruit oil and Pongamol. Water- and sweat-resistant, it helps protect the skin from UV-induced photoageing whilst leaving it supple and nourished. Suitable for children aged 3 and over, it can be used on both the face and body.

Discover the SPF 50 mineral sun balm

Mineral Sun Stick SPF 50

Convenient to take with you wherever you go, this SPF 50 sun stick is specially designed for sensitive areas of the face and body, such as the nose, cheekbones, lips, scars or tattoos. Its certified organic formula combines zinc oxide and Pongamol to provide high protection against UVA and UVB rays. Water-resistant and suitable for children aged 3 and over, it also contains organic passion fruit oil, which helps protect the skin against premature ageing caused by UV exposure.

Discover the SPF 50 mineral sun stick

No, using sun cream does not necessarily prevent the gradual development of a tan. Its main purpose is to limit the harmful effects of UV rays on the skin, particularly sunburn, pigmentation spots and premature skin ageing. Even when protected, the skin may gradually take on a slight tan. However, it is important to remember that a tanned complexion is the result of a defence mechanism triggered by the skin in response to ultraviolet radiation.

Good to know: For those who wish to look healthy and radiant without sun exposure, there are also alternatives such as radiance-boosting skincare products or self-tanning drops.

Infants and young children should not be exposed to direct sunlight. As soon as the UV index rises, seek out shaded areas and protect yourself with a hat, clothing that covers your skin and suitable sunglasses. If you use sun cream, apply it according to the manufacturer’s instructions and reapply regularly, particularly after swimming. Finally, bear in mind that sun cream complements other protective measures, but should not be used to extend the time spent in the sun.

Even when the sun isn’t particularly strong, UV rays can still be present. Before going for a walk, having lunch on a terrace or taking part in an outdoor activity, get into the habit of checking the UV index, just as you would check the weather forecast. This simple habit allows you to easily adapt your protective measures according to the day’s radiation levels.

Stéphanie Catrysse is a naturopath (certified by the FENA), a wellness massage and lymphatic drainage practitioner, and a personal development coach. She is passionate about alternative medicine and practices a holistic approach to health.