Moderate risk. Unprotected skin can burn in 25-30 minutes.
UV index 4 sits in the middle of the moderate range. Burn risk is real for fair skin types, and sunscreen should be standard practice for outdoor activities.
UV 4 is typical of a clear spring or autumn day at mid-latitudes, or morning/late-afternoon in summer. The sun is strong enough to cause visible damage within a lunch break.
Estimated minutes until sunburn begins for each Fitzpatrick skin type at UV 4 without sunscreen or protective clothing.
| Skin Type | Burn Time | With SPF 30 | With SPF 50 |
|---|---|---|---|
| Type I - Very fair, always burns | 15 min | ~45 min | ~60 min |
| Type II - Fair, burns easily | 23 min | ~69 min | ~92 min |
| Type III - Medium, sometimes burns | 38 min | ~114 min | ~120 min |
| Type IV - Olive, rarely burns | 60 min | ~120 min | ~120 min |
| Type V - Brown, very rarely burns | 90 min | ~120 min | ~120 min |
| Type VI - Dark, never burns | 135 min | ~120 min | ~120 min |
Times are estimates based on Fitzpatrick skin typing at UV 4. Actual burn times vary by skin condition, altitude, reflection, and acclimatisation.
Outdoor exercise, gardening, and sports are fine with sunscreen. Plan water breaks in shade for activities exceeding 1 hour.
Yes - UV 4 is in the ideal tanning range (UV 3-5). Keep sessions under two-thirds of your burn time above and build up gradually.
Best UV index for tanning - full guide →Cá nhân hóa ước tính thời gian tiếp xúc với ánh nắng mặt trời dựa trên loại da, chỉ số SPF và quần áo của bạn.
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