The sun is the strongest source of ultraviolet radiation in our environment. Solar emissions include visible light, heat, and ultraviolet (UV) radiation. The UV radiation spectrum is divided into three regions called UVA, UVB, and UVC.
What is the Difference Between UVA, UVB, and UVC?
The three types of UV radiation are classified according to their wavelength. They differ in their biological activity and the extent to which they can penetrate the skin. The shorter the wavelength, the more harmful the UV radiation.
- UVA (315-400 nm): Can penetrate into the deeper layers of the skin and is responsible for immediate tanning effects.
- UVB (280-315 nm): Very biologically active but cannot penetrate beyond the superficial skin layers. It enhances skin aging and promotes the development of skin cancer.
- UVC (100-280 nm): Completely filtered by the atmosphere and does not reach the earth's surface.
Which Environmental Factors Affect a Person's UV Exposure?
Several environmental factors affect a person's UV exposure, including:
- Time of Year and Time of Day: UV levels vary mainly with the height of the sun in the sky.
- Latitude: UV levels are higher closer to the equator.
- Altitude: With increasing altitude less atmosphere is available to absorb UV radiation.
- Clouds and Haze: Cloud cover generally reduces a person's exposure, but light or thin clouds may even enhance UV levels due to scattering.
- Ozone: Ozone absorbs some of the UV radiation that would otherwise reach the Earth’s surface.
- Ground Reflection: Different surfaces reflect UV radiation to varying extents.
Protecting Against UV Radiation
To protect against UV radiation, people can use a variety of measures, including:
- Wearing protective clothing and seeking shade when possible
- Using sunscreen with a Sun Protection Factor (SPF) of at least 30
- Wearing sunglasses that provide 100% protection from UVA and UVB rays
- Avoiding prolonged exposure to the sun during peak hours
The World Health Organization (WHO) has developed a number of resources to help people protect against UV radiation, including the SunSmart Global UV App. This app provides information on the level of solar UV radiation at specific locations and offers time slots when to apply sun protection measures.
By understanding the effects of ultraviolet radiation on human health and taking steps to prevent excessive exposure, individuals can reduce their risk of skin cancer and other related health problems.
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