Tanning booths (sunbeds) emit ultraviolet (UV) radiation, primarily in the form of UVA (315–400 nm), and to a lesser extent UVB (280–315 nm). While natural sunlight contains a balanced amount of both types of radiation, tanning equipment typically emits higher levels of UVA, which can have different biological effects on the skin and overall health. This article examines the medical and dermatological implications of UVA and UVB exposure from tanning booths.
1. UVA vs. UVB: Key Differences
| Characteristic | UVA (Long-wave) | UVB (Short-wave) |
|---|---|---|
| Penetration Depth | Deep (dermis) | Superficial (epidermis) |
| Tanning Effect | Immediate (oxidative) | Delayed (melanin-stimulating) |
| Vitamin D Synthesis | Minimal to none | Primary source |
| DNA Damage Mechanism | Indirect (ROS generation) | Direct (thymine dimers) |
| Carcinogenicity | Linked to melanoma | Linked to squamous cell carcinoma (SCC) |
| Immunosuppression | Strong (systemic) | Moderate (localized) |
2. The medical effects of UVA in tanning machines
A. Skin ageing (photoaging):
UVA penetrates deep into the dermis, breaking down collagen and elastin via reactive oxygen species (ROS).
This leads to wrinkles, leathery skin and solar elastosis (premature ageing).
B. Immune Suppression:
UVA alters the function of Langerhans cells, thereby reducing skin immunity.
This increases susceptibility to skin infections (e.g. HPV and herpes) and may weaken vaccine responses.
C. Melanoma Risk
UVA induces oxidative DNA damage, which contributes to malignant melanoma (the deadliest form of skin cancer).
Studies show that people who use tanning beds have a 59% higher risk of developing melanoma (JAMA Dermatology, 2014).
D. No significant vitamin D production
Unlike UVB, UVA does not convert 7-dehydrocholesterol into vitamin D₃, meaning that tanning beds are ineffective for synthesising vitamin D.
3. Medical effects of UVB in tanning machines
A. Sunburn and DNA damage
UVB causes direct DNA mutations (thymine dimers), which increases the risk of squamous cell carcinoma (SCC) and basal cell carcinoma (BCC).
Tanning beds with UVB contribute to erythema (sunburn).
B. Vitamin D synthesis (limited in tanning beds)
While UVB is necessary for vitamin D₃ production, most tanning machines minimise UVB exposure to reduce the risk of burns, which makes them inefficient for this purpose.
C. Localised Immune Suppression
UVB reduces the number of antigen-presenting cells in the skin, but causes less systemic immunosuppression than UVA.
How to deal with UV damage:
Wear protective sunglasses.
Use sunscreen with UVA/UVB protection.
Choose low-radiation equipment.