Some estimates of local variations in ozone level in a polluted atmosphere

Calculations are presented on the shape and size of the zone in the atmosphere where the ozone concentration is reduced on account of contamination with oxides of nitrogen. It is shown that the local effect of the contamination is small and short - lived, but that oxides of nitrogen taken globally form a persistent catalyst that progressively reduces the ozone level in the atmosphere. However, predictions on the latter effects are difficult because the available values for the photochemical reaction constants are very imprecise, as are the values for the levels of various minor components, in particular atomic nitrogen.