Comment on two articles, 3 September 2001 issue of Eos



In “Reassessing Past European Gasoline Lead Policies” by von Storch et al., beginning geophysics students will be impressed by the superb precision in Figure 1, which relates to 110 587.9 ton of European lead emissions in 1965. Recalling their freshman physics, they will note that the last digit given has some significance; that is, it is presumably close to 9 and is not 8, nor is it 0. Thus, the full number should be meaningful to plus-or-minus 0.1 ton, which happens to be about my mass. Hence, the number is apparently good to one part in 10,000,000; the reader is invited to search for similar precision in geophysics.