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This study aims to establish Lebanese national diagnostic reference levels (NDRLs) for full field digital mammography (FFDM) and digital breast tomosynthesis (DBT). Data were collected from 34% of the total number of health facilities with FFDM and/or DBT units in Lebanon. NDRLs were set as the third quartile of mammography units’ median value of average glandular dose (AGD). NDRLs for different compressed breast thickness (CBT) and age groups were also proposed. Statistical analysis were performed to test the difference of AGD between cranio caudal (CC) and medio lateral oblique (MLO) views, FFDM and DBT, and AGD across health facilities, CBT and age groups. Data from 2803 women with a total of 10462 images were included in the study. For FFDM and DBT, NDRLs for CC and MLO views were equal to 1.85 and 2.24 mGy, and 2.65 and 3.04 mGy, respectively. Lebanese NDRLs were higher than most published DRLs while remaining below the European Commission’s maximum acceptable dose level (2.5 mGy) for FFDM. AGD increased significantly (p < 0.05) with the increase in CBT for both views and techniques. This first set of mammography DRLs reveals the need for optimizing the radiation exposure in Lebanon and will serve as a national/international benchmark.

The problem of determining the concentration changes of reactive hydrocarbon immissions as a function of time was solved by means of an automatic gas chromatograph which, without enrichment, could record ethylene and acetylene in ppb concentrations. At the same time various other pollutants were covered, so that by a mutual allocation of the individual components it was possible to identify certain emitter groups. The results clearly show that ethylene and acetylene primarily originate from the combustion processes of the automobiles, while the handling and storage of petroleum products and their processing do not exert any influence on the immission of the two components. By way of time series measurements during a summer week in 1976 with very intensive solar radiation it was possible to show indirect secondary photochemical reactions.

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