BUDDHA BASNYAT,
Amazingly, pollution-related ozone concentrations in the Mount Everest region are reported to be very high as shown by John Semple, colleagues from the University of Toronto in a 2009 March issue of the New England Medical Journal. This is potentially alarming because death rates from respiratory causes are associated with increasing concentrations of ozone. The Mount Everest region is somewhere you can inhale deeply without feeling a burning throat sensation as you do when you complete such a manoeuvre in Kathmandu. But if the ozone story is true, our lungs may be in for a rough ride even in the pristine Solukhumbu Valley.
Ozone concentrations in the troposphere have doubled globally since preindustrial times. They are now 30 ppb from estimates of 15 ppb in the pre-industrial era. And, not surprisingly, the major reason for this is burning of fossil fuel. (Not to be confused with the stratospheric ozone layer which is "good" ozone and protects the planet from harmful ultraviolet rays from the sun.)