Air pollution

Press, 12 July 1979, Page 16

Air pollution

Sir, — I wish to take issue with my namesake G. Boston (June 30) when he says that “the recent high pollution readings . (in Christchurch) may not have been from manmade sources.” Your graph of the same date and page shows that smoke and nitrogen oxides are twice as great in the central city as in the suburbs. Indeed, pollution is worst in Christchurch in the winter and at night when plants are least active. We know that the Los Angeles smog is caused by the action of sunlight on the waste gases of motor vehicles and heavy industry, oxidising them into highly noxious sub-

stances which are soluble in water. The resultant vapour together with carbon particles is known as photochemical smog and is worst in summer. Quite clearly therefore smoke, smog and photochemical pollution are the products of human activity. — Yours, etc., Dr G. H. BOSTON. July 7, 1979.

Sir, — Your correspondent D. W. King (July 9) quotes references to smog in 1911. I stand corrected. Glasgow and Edinburgh are not afforested areas, and while Reefton is in the vicinity of bush-clad slopes, it. does not meet the term 1 used, densely afforested. The two cities usually mentioned as having the worst smog problem, Los Angeles and Tokyo, are certainly not renowned for trees in large numbers. My point was, that if vegetation was the cause of smog, surely the worst evidence should be in the vicinity of major afforested areas, which it is not. — Yours, etc., (Mrs) A. J. FLANAGAN. July 9, 1979.