UV index and exposure level for various UV intensity

UV intensity (W/m2) UV Index Exposure level Protective measures

0-20

0-2

Low

  • No special protective measures required.

21-35

3-5

moderate

  • Seek shade during midday hours when staying outdoors
  • Use a sunscreen lotion that can block both UVA and UVB (with SPF 15 and PA+, or above)
  • Wear long-sleeved and loose-fitting clothing, wear a broad brim hat, use an umbrella, wear sunglasses

36-45

6-7

High

46-55

8-10

Very high

  • Avoid being outdoors in the sun during midday hours
  • If you must stay outdoors, seek shade
  • Use a sunscreen lotion that can block both UVA and UVB (with SPF 15 and PA+, or above)
  • Wear long-sleeved and loose-fitting clothing, wear a broad brim hat, use an umbrella, wear sunglasses

>=56

>=11

Extreme

Source: Hong Kong Observatory (2014).