Sunblock

Going to the beach or out into the desert on a sunny day it's common sense that you would bring along sunscreen and make sure that you're protected against sunburn, and climbing into the mountains should be just the same. Although the weather is much cooler and it may even be cloudy, the atmospheric conditions bring an increased risk of burning. At higher altitudes the atmosphere becomes thinner, and the air and airborne particulates that normally shield us from much of the ultraviolet rays are much more transparent. Above 9,000 feet especially, where the atmosphere is 30% thinner, the rays of the sun hit much more directly, and since the activity of hiking involves exposure to the sun practically all day, the danger is greatly intensified. Even on a cloudy day some of the harmful sunlight passes through the overcast skies. Ultraviolet let also penetrates clothing, and over prolonged exposure can develop into sunburn under covered areas.

The best policy when spending a lot of time in the daylight is to expect that the sunlight is a danger to your skin and eyes. For exposed skin you will need to apply sunblock that has a strong SPF (sun protection factor). The SPF indicates multiplier of the time it will extend your skin's natural resistance to sunburns. SPF 10 suggests that it will extend the protection by ten times normal, though the natural protection is difficult to pin down due to the intensity of the sun and the complexion of the skin. In general the natural protection is between 5 and 10 minutes. For activities in the water or that bring about excessive perspiration it is important to keep the sunblock on, so either use a waterproof lotion or reapply regularly. It is also very good to wear clothing to cover as much of the skin as possible, such as long pants, a long-sleeved shirt, and a hat with a sun visor. Don't forget to protect your eyes with sunglasses. Most normal eyeglasses have built-in ultraviolet like blocking, and wearing tinted or darkened lenses greatly reduces fatigue from squinting. Anything you can do to reduce discomfort while on a long hike really helps.