We are permanently exposed by ionizing radiation produced by radioactive matter in and on the ground and in the atmosphere, and by cosmic radiation. Further contributions are caused by man-made radiation sources, contaminated food and contaminated commodities. Its damaging effects on biologic organisms depend on the nature of radiation (Alpha-, Beta-, Gamma-radiation) (more). The dimension Sievert (Sv) has been introduced to describe its biologic effectiveness (more).

The mean annual exposure ("dose") applied e.g. to the population in Germany amounts to approx. 3.9 mSv. Natural sources contribute 2 mS. A second part of 1.9 mSv is due to man-made sources such as the fallout of past nuclear weapon tests, accident of nuclear facilities, and medical application (X-ray and CT, nuclear imaging, radiation therapy). This corresponds to a continuous dose rate of 0.23 μSv/h and 0.216 μSv/h rsp., and amounts to a combined average dose rate of 0.446 μSv/h. This values is indicated in all time charts to provide a reference for the assessment of the actual situation.

The presently installed sensor stations register the exposure of Gamma-radiation emanated from the atmosphere only. We do not apply any weighting with respect to the biologic effectiveness vs. the nature of radiation. Neither we compensate for the nonlinearity of the detector related to the Gamma spectrum. Nevertheless we apply the dimension Sievert per hour (Sv/h) for the representation of the readings to facilitate a comparative estimation of the exposure situation. Hence the readings must only serve as an indicator for abnormalities and for the tracking of trends.

On the following pages we provide a short introduction into the measuring process for ionizing radiation. Furthermore we describe the system components of the monitoring network, i.e. the sensor stations for the detection of the local doserate, the server for data collection, archival, processing and publishing, and communication links between sensor stations and server.

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