The present status of investigations of acid rain, stratospheric ozone depletion and greenhouse effect and their relations to radiation exposure are reported. Soil acidification increases transfer rates of radioactivities to plants which increases the population dose. There are two types of ozone depletion, conventional type and ozone hole type and the latter is much more serious than the former. In the greenhouse effect, although there are large uncertainties both in theoretical and observational sides, present predictions about the global warming will not be very far from reality. Environmental effects are wide-ranging and serious. Radon and thoron exhalation rates are affected by the global warming. The influence of the greenhoure effect on ozone depletion is to suppress depletion for conventional type and enhance depletion for ozone hole type.

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A new simplified method for particle size estimation of radioactive aerosols was proposed for air monitoring. It does not need any new instruments but a traditional aerosol sampling device with a multistage filter system. The method is based on the particle size dependency of penetration for air filter. Decontamination factor data measured in each filter stage is inversed to a size distribution of aerosols. When air filter for a dust sampler such as Toyo HE-40T is used, the method can be applied for a size estimation of aerosols ranging from 0.2 to 10μm in which ICRP is interested for lung deposition model. In a size measurement of ¹⁹⁸Au aerosols, it was shown that the size distribution estimated by the present method was in a good agreement with the distribution by the existent method using a cascade impactor.

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Pressurized ionization chambers have been widely used as environmental radiation dose rate detectors because of their high sensitivity and wide-range adaptability. But their energy responses were not quite desirable especially in the region lower than 200keV. So we intended to develop a pressurized ionization chamber which has a flat energy response that corresponds to absorbed dose rate to air.
First we calculated the energy response of ionization chamber according to BURLIN's formula, modifying BRAGG-GRAY'S cavity theorem so that it took acount of interaction of photons or electrons in the cavity. Then we chose the most applicable wall material and filling gas. Aluminum wall was thought to be better than SUS wall that has been widely used. As for the filling gas, N₂ was chosen because it consisted of a major part of air, and a few percent of Ar gas was added to compensate lower energy response. As a result, developed 8-atom pressurized chamber could have energy response of ±15% for energy range from 60keV to 1.5MeV, and that agreed well with the calculated results.

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The performance of a dust respirator is affected mostly by the leakage through the interstice between mask and face. Mask man-test using NaCl aerosols has been developed to evaluate protection provided by worn masks. However, there are some problems in application of man-test to field test.
The sampling method of the NaCl aerosols inside the mask was discussed. The tool for sampling operated easily was selected, and the best sampling position at the mask was decided.
The correction of the measured values was also discussed. Because of NaCl aerosols deposition in the respiratory tract and sampling lines, the leakage might be underestimated. The correction coefficient was experimentally measured and discussed.

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Food consumption survey was carried out in Tokai-mura, Ibaraki prefecture, during the period 1983-1986, in relation to the calculation of the internal radiation dose for inhabitants living around the nuclear reprocessing plant. The investigator made house-to-house visit to inquire about the food consumption during one day and additionally to request that a dietary diary be kept for 5 consecutive days. Average consumptions for the over school-age members of the family were calculated. From the 5-day survey, it was recognized that the average daily intakes of vegetables and aquatic products including fresh water products were 446g (wet)/d/p and 159g (wet)/d/p, respectively. Consumptions of vegetables and aquatic products increased about 100g and 70g, respectively, compared to those of our previous survey in Tokai-mura during the period 1970-1973.

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