Ultraviolet Radiation and Health
The sun emits radiation of different wavelengths, including ultraviolet (UV) radiation, which is invisible and cannot be felt.
A moderate amount of sun exposure helps our body to produce vitamin D, which is important for keeping our bones healthy.
Excessive exposure to UV radiation may cause painful sunburn, wrinkling and premature ageing of the skin, as well as an increased risk of skin cancers and cataracts.
The UV Index and Forecast
The Hong Kong Observatory measures and forecasts UV intensity, adopting the scheme provided by the World Health Organization (WHO) to calculate the UV Index and classify it into the corresponding exposure level.
The UV Index is a measure of the potential harm of UV radiation on human skin. The higher the number, the greater the potential for damage to the skin. In Hong Kong, the UV index value can often exceed 10 on a sunny day in the summer.
The UV Index and the corresponding exposure level defined by the WHO are shown in the table below:
UV Index |
Exposure Level |
0-2 |
Low |
3-5 |
Moderate |
6-7 |
High |
8-10 |
Very High |
>11 |
Extreme |
Protective Measures against UV Radiation
Sun Safety Tips for Children
Children are at a higher risk of UV damage than adults, and therefore require special protection. To enjoy the sunshine with them, parents/carers should consider the following tips: