Sunstop

How the estimate is made

Sunstop uses a published dermatology model: the minimal erythemal dose for each Fitzpatrick skin type, divided by the day's peak UV index from the local forecast. Your skin type comes from a short self-assessment quiz. Sunscreen, if you enter an SPF, is accounted for with a heavily discounted factor because real-world application is thinner than the lab standard, and every session is capped at 120 minutes regardless of SPF.

The model cannot see your skin. It does not know about medication that increases photosensitivity, recent sunburn, pregnancy, skin conditions, a family history of skin cancer, or reflection from water, sand and snow. All of these can make the real threshold much shorter.

What Sunstop is NOT

Not a medical device

• It does not diagnose, treat or prevent sunburn, photoaging or skin cancer.
• It is not a substitute for a dermatologist or your doctor.

Not a promise of a tan, and not a “safe tanning” tool

• There is no safe level of UV tanning. A tan is the skin's response to damage.
• Sunstop never promises a tan and never encourages more exposure than you planned. The product tells you when to stop.

Not a guarantee

• Forecasts can be wrong. Clouds, altitude and reflection change real UV exposure.
• Reminders can be missed if notifications are off, the phone is off, or the app was force-closed.

All skin types burn

Darker skin (types V and VI) burns less readily but still burns, still ages from UV, and still gets skin cancer, often diagnosed later. Sunstop gives every skin type the same care and the same disclaimers.

Basic sun safety, regardless of what the app says

• Use broad-spectrum sunscreen SPF 30 or higher, apply generously, reapply every two hours and after swimming or sweating.
• Seek shade when the UV index is 3 or above, especially between 10:00 and 16:00.
• Wear a hat, sunglasses and clothing that covers skin.
• Never use sunbeds.
• Check your skin regularly and see a doctor about any new or changing mole or spot.
• Children and people on photosensitising medication need extra protection; the app's estimate does not account for either.

Vitamin D

The vitamin D figure is a rough estimate of cutaneous synthesis and is shown for context only. It is not dietary or medical advice. Most people can meet vitamin D needs through diet and supplements without deliberate sun exposure; ask your doctor.

Sources

• World Health Organization, Global Solar UV Index: A Practical Guide.
• Fitzpatrick TB, The validity and practicality of sun-reactive skin types I through VI, Arch Dermatol 1988.
• Your national skin cancer prevention body (for example the American Academy of Dermatology, Cancer Research UK, or the Skin Cancer Foundation).

Limitation of liability

By using Sunstop you accept that we are not liable for sunburn, skin damage or any health outcome from decisions you make based on the app. The full limitation is in §9 of the Terms of Service.

Contact

Questions about how to read a result: support@aylanapps.com.