We, as pilots, know how much influence the sun has on the weather and by extension, the aircraft. The sun heats the air and causes all the unfavourable and favourable weather events for us to fly in. But do you know how much the sun affects our skin?
The sun emits UV rays. The rays are sub-divided into UVA, UVB, and UVC. UVC (shortest wave-length) gets completely absorbed by the Earth’s ozone and atmosphere so it doesn’t reach the surface. UVB damages DNA and causes most sunburns. UVA penetrates deeper into the skin and accounts for 95% of all the UV radiation that reaches the Earth’s surface. We spend roughly 2 hours per flight under the sun so it’s a good idea to know how the sun can affect our biggest organ.
UVC has the shortest wave-length, meaning it has the highest energy, so it has a higher chance to damage our DNA. Fortunately for all life on Earth, the ozone blocks UVC. The base of the ozone varies depending on the season and latitudes, but starts around 42000’. Most flights rarely go above 40000’ and even if they do, it’s towards the end of the flight. Therefore, UVC isn’t a major concern.
The amount of UVB does decrease as it reaches the surface of the Earth due to the ozone and a thicker atmosphere. Unfortunately, it’s not enough to reduce the damage caused to us. The majority of information that you know regarding UV damage is caused by UVB. It’s the main cause of sunburn and skin redness, skin cancer, tanning, etc. UVB is most intense from April to October between 1000 and 1600. The usual method to minimize the amount of UVB exposure is limiting time outside, which doesn’t quite work since most training flights occur during day VFR. The next best solution is by wearing sunblock and/or covering up exposed skin with clothing. The majority of UVB have trouble penetrating glass so there is somewhat of a filter for UVB in the aircraft.
UVA can penetrate clouds and glass because it has a longer wavelength so roughly 95% of it reaches the surface of the Earth. It affects deeper into the skin compared to UVB. UVA is the main cause of wrinkles, photoaging, and some types of skin damage and skin cancer. Due to its longer wavelength, it’s not as intense as UVB, but because it’s so prevalent throughout the year, the accumulative damage adds up. Similar to UVB, we wear sunblock and/or proper clothing to protect us from UVA, but with a caveat covered in the next section.
Sunblock (and Sunglasses)
SPF (Sun Protection Factor) is used to measure the effectiveness of sunblock. Generally, at least a minimum of SPF 30 is recommended. However, SPF is primarily a measurement for blocking UVB. In Canada (and US), there is currently no regulated measurement of how effective a sunblock is in preventing UVA damage. The next closest are the words “broad spectrum” on the container that indicates the sunblock formulation covers the UVA-UVB spectrum. Unfortunately, the requirements to include “broad spectrum” are so low and vague that the sunblock may not necessarily provide proper protection. There is a rating used for UVA, but it’s primarily used in the Asian markets. Look for at least PA+++ (PA++++ is highest) in addition to an SPF 30+ on the package. EU markets use a “UVA” icon to indicate the amount of UVA protection is at least 1/3 of the UVB SPF protection.
When applying sunblock, use liberal amounts to ensure all exposed skin is covered and reapply every 2-3 hours.
We need our medical, hence our eyes, to fly. UV rays can cause cataracts and invalidate our medical. Simply get glasses with UV 400 rating to reduce the amount of eye damage. Plus, it makes us even more exceptionally cool!