ECHOES AND UPDATES

Why is ozone good in the stratosphere, yet persecuted by the EPA on the ground? asks a reader. Because two different proper-ties of it are involved. When sunlight strikes an ozone molecule, it breaks it down to oxygen molecules of one and two atoms each. The energy needed for this break-up is, because of a basic quan-tum-mechanical effect, taken from the ultraviolet component of sunlight which would be harmful to life if much of it reached the earth. By making this component spend itself (absorbing it), ozone is a good guy.

Ozone is also produced by complicated photochemical reac-tions in sunlight in the presence of hydrocarbons (such as automo-bile exhaust gases) and gives rise to smog, especially if trapped on windless days in terrain such as the Los Angeles basin. It then causes short-term irritation of the lung and possibly chronic ef-fects, also damaging plants and certain materials (rubber, paints). The property involved in such damage is ozone's very strong oxidi-zation capability: it oxidizes (much the same as "burns") most materials with which it comes in contact. In water treatment plants this is welcome, and artificially made ozone is used in some of them to destroy toxic materials as well as bacteria; but it is this property that makes it a bad guy when it arises inadvertently.

New data, or their absence, on genetic damage by radiation were reported at the 16^th International Congress of Genetics in Toronto in August. A report was delivered on the search for child-hood cancers, birth defects, infant deaths, chromosome damage and other health effects among 24,000 children whose parents were known to have been exposed to large doses of radiation in Hiroshima or Nagasaki. No statistically significant differences were found when compared to a control group of children of parents known not to have been exposed. The study, now in its fifth decade, is the largest body of data on genetic effects of ionizing radiation in humans. The result does not agree with the post-war estimates based on experiments with mice, and some health physi-cists now hypothesize that humans may be three times less sensi-tive to radiation than mice.

I lost any enthusiasm for Margaret Thatcher when she sold out Hong Kong to the Red Chinese, but I have to give her credit for abolishing tenure for new appointments at British universities. Tenure is needed only by the incompetent, and is in the US given only to professors and government bureaucrats (evidently because of their more acute need in this respect). Talk about academic freedom in institutions that persecute dissident editors (Dart-mouth), do not let opponents of totalitarianism speak (Harvard), threaten their life (Northwestern), and otherwise give a free hand to the stormtroopers of the Left (most of them) is irrelevant and hypocritical.