introduce
The sun emits rays that can penetrate our skin. While these rays are essential for health, they can also have harmful effects. Children's skin is more vulnerable to UV damage than adults', with weaker resistance, and sunburn can take years to heal. Therefore, childhood is a critical period for sun protection, and parents play a vital role in protecting their children's skin. Learning to recognize the dangers of sunlight is essential for providing appropriate protection for your baby!
Solar radiation
Different types of radiation
Of the solar radiation reaching Earth, three types can affect our bodies:
• Visible light (visible to the human eye)
• Infrared (IR)
• Ultraviolet (UV): UVA and UVB
The ozone layer blocks ultraviolet radiation (UVC) with wavelengths below 290 nm and the shortest UVB (280-290 nm), preventing them from reaching the Earth.
Effects on the skin
The effect of light on the skin depends on its wavelength: the longer the wavelength, the deeper it penetrates the skin. Therefore, UVA and UVB have different effects.
• UVB rays cause sunburn, skin aging, and even skin cancer, and are harmful to the skin.
• UVA penetrates deeper, causing tanning, skin aging, and wrinkles. Although UVA is less intense than UVB, it is more abundant: it accounts for 98% of all ultraviolet radiation, while UVB accounts for only 2%. Furthermore, UVA is present consistently throughout the day and year, while UVB is strongest at midday and in summer, and weaker in the morning, evening, and winter.
Good sun protection should protect against both UVA and UVB rays.
Absorbed radiation
The amount of solar radiation absorbed by the skin depends on several factors:
• Season: In July in the Northern Hemisphere, the risk of sunburn from UVB rays is 100 times higher than in winter.
• Latitude: The equator receives the strongest sunlight because the sun shines directly on the earth, and the distance it takes to pass through the ozone layer is the shortest.
• Altitude: UVB exposure increases by 4% for every 300 meters (about 1,000 feet) of elevation gain, which explains why the risk of sunburn is high in mountainous areas.
• Time: Sunlight is at an angle in the morning and evening, with the strongest UVB from 11 am to 2 pm.
• Clouds: Clouds can filter out ultraviolet rays to some extent, but you can still get sunburned on cloudy days.
• Ground properties: Different reflectivities, snow (85%), sand (17%), water (5%), grassland (3%). Therefore, mountainous areas are particularly dangerous because of the high altitude and the strong reflectivity of snow.
• Water surface: It can reflect up to 20% of ultraviolet rays, so there is a risk of sunburn even in water.
The effects of sunlight on the skin
Positive impact
Sunlight promotes vitamin D synthesis, stimulates calcium metabolism, and promotes bone growth. Sunlight can also improve mood; moderate sun exposure can prevent seasonal affective disorder.
Negative impact
Solar radiation can cause both short-term and long-term harm:
- Several hours after sun exposure, depending on the duration and intensity of exposure and skin type, the following may occur:
• The infrared thermal effect can cause heatstroke (dizziness, headache) and even heat exhaustion (dehydration, confusion), which is especially common in children.
• UVB and some UVA rays cause sunburn on the skin.
- Prolonged and repeated sun exposure without protection can damage skin cells:
• UVA accelerates skin aging and damages elasticity.
• The combined effects of UVB and UVA may trigger skin cancer (photocarcinogenesis). Skin cancer includes:
• Epithelioma: Presents as a small, round, white or pink protrusion or a persistent crust.
• Malignant melanoma: appears after changes in normal skin or moles.
Early detection of melanoma requires attention to changes in the appearance, color, shape, or thickness of the mole, and regular consultation with a doctor.
