UV radiation is a form of electromagnetic energy from the sun that can damage skin cells, leading to premature aging and increased cancer risk. While the cabin environment feels controlled and safe, the high altitude at which commercial jets cruise significantly alters the amount of UV radiation reaching the aircraft. This unique combination of high-altitude exposure and the properties of aircraft materials makes sun protection during flight a necessary consideration.
The Science of Increased UV Exposure at High Altitudes
Commercial airliners typically fly at altitudes between 30,000 and 40,000 feet, where the atmosphere is considerably thinner than at ground level. The atmosphere, including the ozone layer, acts as the Earth’s natural sunscreen, absorbing much of the sun’s UV radiation. As an aircraft climbs, there is less protective atmosphere above it to filter these rays.
For every 3,280 feet (1,000 meters) of altitude gained, the intensity of UV radiation increases by approximately 12% to 15%. This means that at a typical cruising altitude of 30,000 feet, the total UV radiation can be up to double the intensity experienced at sea level. This effect is further magnified when flying over dense cloud cover or snow, as both surfaces can reflect up to 85% of UV radiation back up toward the aircraft.
The direct path to the sun at altitude also means window seats, particularly on long daytime flights, expose passengers to intense, continuous UV light. This atmospheric thinning is the primary reason UV exposure is a concern during air travel. Studies suggest that pilots and flight crew have a higher incidence of melanoma, indicating a clear link between frequent flying and elevated UV risk.
How Aircraft Windows Filter UV Radiation
Standard commercial aircraft windows are constructed to handle the extreme pressure differential between the cabin and the outside air, but their material composition has a variable effect on UV light. The windows are generally made of multi-layered materials, often incorporating acrylic or polycarbonate, which are highly effective at blocking one type of UV radiation.
These materials block nearly all UVB rays, the shorter-wavelength radiation responsible for causing sunburn. However, the longer-wavelength UVA rays, which penetrate deeper into the skin and are linked to premature aging and skin cancer, are not as fully blocked. Standard passenger windows can allow a significant amount of UVA radiation to pass through, with some studies showing a transmission rate of up to 50%.
The cumulative effect of UVA exposure is the primary concern for passengers, as it can cause damage over time without the immediate warning of a sunburn. Newer aircraft window technologies are emerging that incorporate specialized treatments to block more than 99% of both UVA and UVB rays, but these are not yet universally implemented across all fleets.
Essential Sun Protection Strategies for Air Travel
Given the heightened UV intensity at cruising altitude and the incomplete filtering capabilities of most aircraft windows, a proactive sun protection strategy is recommended for air travelers. Applying a broad-spectrum sunscreen with a Sun Protection Factor (SPF) of 30 or higher is the most direct way to mitigate this risk. This sunscreen should be applied to all exposed skin, including the face, neck, and hands, approximately 30 minutes before boarding.
It is also important to reapply the sunscreen every two hours on long-haul daytime flights, as its effectiveness diminishes over time. Physical barriers offer additional protection and are highly effective.
Travelers should also utilize physical barriers:
Protection Measures
- Keep the window shade closed, particularly during the middle of the day when the sun is highest.
- Wear protective clothing, such as long-sleeved shirts and pants made of tightly woven or UV-protective fabrics.
- Wear UV-blocking sunglasses to shield the eyes from intense UV exposure, which is important even if the window is closed.
For frequent flyers or those who often take daytime window seats, these measures are particularly important to limit cumulative exposure.