I have, for much of my life, lived close to sea level. Most people don't think too much about altitude, unless they travel a lot, climb mountains, or are professional athletes. If you live near hills or near mountains, you might not even think too much about a hike or drive up a couple thousand feet, or a few hundred metres or even a kilometre in elevation above where you live. You might not even notice it that much, particularly if you are driving. If you are hiking, well - any trouble breathing you may have can usually be blamed on exertion, and that spare tire you may be carrying. Certainly, hiking in the mountains around Vancouver, Canada, or skiing at Whistler when I was younger, I never had any problems. The base was a couple thousand feet above sea level, and that was no problem at all. Taking the lift up another 3000 feet (900m) or so and skiing back down, perhaps I felt it, but as I was not that confident a skier I had other things on my mind, like avoiding the row of trees up ahead. There are times, though, where changes in altitude can have a serious impact on you.  Specifically, the rate of change is a critical factor that can be life-and-death for you - and also for your projects. Listen to the podcast or read the full article on Gazza's Corner Blog.