(Comment) ICRP should provide a dose conversion convention that depends on smoking habits on the basis of scientific knowledge. It should be left to the discretion of each country to determine how radon exposure should be regulated, e.g., using the simple regulation for radon concentration, the detailed regulation for dose due to radon exposure using the dose conversion convention given in proportion to the degree of smoking habit and so on. (Reason) ICRP indicates that the lifetime excess absolute risk (LEAR) due to radon exposure increases in proportion to the degree of smoking habit. However, the ICRP recommends the simple dose conversion convention including smoking habit effects. Since the smoking habit of members of the public and workers under radon regulation would be vary according to the characteristics of the population, the recommendation of the simple regulation for radon concentration does not lead to a scientific and rational radiation safety regulation. As a conclusion in this draft report, the ICRP proposes to treat radon and the radon progeny in the same manner as other radioactive nuclides, and to publish dose coefficients calculated using dosimetric models. However, the current dosimetric models do not involve and cannot account for smoking habit effects. Therefore, it is inappropriate to simply give the dose coefficients for radon exposure using such dosimetric models.