The UV index is a number that tells you how strong the sun's ultraviolet radiation is expected to be at its peak that day. It is reported for the four hours around solar noon, which falls between about noon and 2 pm depending on where you are1. The World Health Organization recommends sun protection whenever the index is forecast at 3 or higher1.
| Index | Category | What the WHO advises |
|---|---|---|
| 0 to 2 | Low | Little protection needed |
| 3 to 5 | Moderate | Shade at midday, shirt, sunscreen, hat |
| 6 to 7 | High | Shade at midday, shirt, sunscreen, hat |
| 8 to 10 | Very high | Avoid being outdoors at midday |
| 11 and above | Extreme | Avoid being outdoors at midday |
Why Malaysia gets so much of it
MetMalaysia, the national weather service, explains that the closer you are to the equator, the shorter the path sunlight takes through the atmosphere, so more UV reaches the ground. It also rises with the sun's height and with altitude, by about 10% for every 1,000 metres3. The department publishes an hourly UV index from 11 am to 4 pm3.
We could not find an official MetMalaysia statement of a typical range for the country, so we will not quote one. A conference paper on measurements at Petaling Jaya reports maximum readings of 13 in 2016 and 2017 and 14 in 2018, but we only saw its abstract, so treat that as an indication, not a rule5. The number that matters is today's, for your town, on the MetMalaysia site.
Cloud, heat and windows do not help much
- Thin or light cloud does little to cut UV and can even increase it by scattering the light. MetMalaysia says a cloudy day does not mean you cannot burn3.
- You cannot feel UV, and it has nothing to do with the temperature3.
- UVA is about 95% of the UV that reaches the ground, keeps a similar strength through daylight all year and passes through windows and cloud. UVB is filtered by glass4.
What SPF and PA actually tell you
SPF measures protection against UVB, the rays that cause sunburn. SPF 15 filters about 93% of UVB, SPF 30 about 97% and SPF 50 about 98%, and no sunscreen blocks everything7. Broad spectrum means it also protects against UVA7.
PA is the Japanese grade for UVA. It is measured as UVAPF, and PA++++ means a UVAPF of 16 or more. The label must be shown together with the SPF6. That is why a sunscreen sold in Malaysia can carry both, for example SPF 50 PA++++.
What to do about it
- Wear a broad-spectrum SPF 30 or higher every day you go outside, and reapply about every two hours when you are out8.
- MetMalaysia is clear that shade, clothing and a hat are the best protection, and that sunscreen is for exposed skin, not for staying out longer3.
- Darker skin has more melanin and a lower skin cancer rate, but skin cancer does occur and is often found later. Eye damage does not depend on skin colour3.
