I wish to comment on natural radiation doses, particularly your paragraphs 283 and 285. It would help if paragraph 285 would give a range of the doses from terrestrial external gamma radiation and an estimate of the population fraction (or actual numbers) exposed to the higher end of the distribution. In paragraph 283 you state that inhabited areas of the world have annual doses from natural sources are much higher than 10 mSv. Since it is likely that this small fraction of the world population should receive the most dose reduction attention, a more detailed description of the source of this 10+ mSv exposure would be useful. For example, is the very high tail of the frequency distribution mostly from terrestrial gamma, internal emitters or radon? Thank you for the oppurtunity of commenting. Wesley R. Van Pelt, PhD, CIH, CHP, Fellow of the Health Physics Society.