Sixty Miles Up

Today we are walking 60 miles along the surface but if we were able to walk sixty miles up we would get out of breath and very cold after just 5 miles which at the top of the mount everest is the highest we can physically walk and to do that most people need the help of oxygen.

Unlike the bottom of the atmosphere that we are walking through there is no hard edge at the top, the air gets thinner and thinner and the molecules further apart and some of the smallest and lightest at the top manage to escape the pull of the earths gravity and are lost to space.

At 15 miles up the oxygen in the upper atmosphere is constantly absorbing the most intense ultraviolet radiation, reducing its life damaging rays by turning them to heat. Each day, the sun’s ultraviolet creates 12% more ozone, then, every night, without the sun to keep making it, it reverts back to oxygen releasing some heat as it does so.

While I was growing up in London, industrial chemicals from aerosols and fridges escaped in apparently harmless quantities into the air I breathed. Although they appeared to cause me no harm, they were enough to disrupt this whole planetary ozone making process and let much more ultraviolet through. Fortunately, our observant scientists spotted what was going on and persuaded our policy makers to reverse the trend. Unfortunately, I’ll be long dead, maybe from cancer, before the levels recover fully to what they were when I was born, but the next global generation should see the benefit.

As we rub sunlotion on, in the midsummer sun today, we will remember that the 60 miles of air we walk through today is precious and vulnerable in unexpected ways to our modern rubbish.

And carry on supporting the scientific research that will unexpectedly find threats we never saw coming and keep us safe again.