[Microclimatic and air ionization problems in electronic telecommunication centers]. / Mikroklimatichni i aeroionizatsionni problemi v elektronni telekomunikatsionni tsentrali.

The electronic automatic telegraph stations are up-to-date telecommunicative equipment. There is no information in literature for hygiene characteristic of the working conditions in this type of modern industrial activity. The study shows, that the basic hygiene problems are related to the microclimate and ionization of the air of the working premises. The climatic installation creates extremely static microclimate during all the periods of the year and systematic aero-ionic insufficiency of the air. Possibilities for regulating the climatic installation regime are discussed in view of establishing physiologically sound and well-grounded microclimate and aero-ionic conditions.

[Occupational risk of asbestos injuries among workers in the asbestos cement industry]. / Profesionalen risk ot azbestovi uvrezhdaniia sred rabotnitsite ot azbesto-tsiemntovo proizvodstvo.

Dustiness in the asbestos-cement production department of the "Vulkan" plant in Dimitrovgrad was studied. The assay included concentration, dispersion, substance composition, morphology, asbestos content. Two types dustiness were encountered: In the storage and mixing shops the aerosol contained 7 to 78 percent asbestos needles, free from agglomeration; in the moulding and turnery shops the asbestos content rangeal from 2 to 21 percent. Considerable part of the needles were amalgamated by the cement and could be detected only on electron-microscopic observation. The total amount of inhaled asbestos exceeded the amount inhaled at threshold concentration of 0.2 mg pure asbestos aerosol 9 times in the preparatory division and from 2 to 14 times in other shops. In the moulding shop the content was lower than the threshold one. Elevel cases of asbestosis were established: 3 in the preparatory, 4 in the turnery and 3 in other shops. In five cases there were pleural plaques in addition to the parenchymal changes. The minimal length of service to develop asbestosis was 13-14 years at the preparatory division (more free asbestos in the aerosol) and 20-21 years at the turnery shop (less, but agglomerated asbestos). Work with asbestos-cement exposes the workers to a serious risk of development of asbestosis. No principal difference was established in the biologic activity of the two aerosol types; there only is a difference in the degree of their aggressiveness.

[Occupational risk in asbestos textile manufacture]. / Profesionalen risk pri asbestotekstilnoto proizvodstvo.

Detailed investigations of the environment in asbestostextile industry ("Asbestos produce" plant in the town of Sevlievo) were carried out. The parameters determined were: overall dusting, amount of asbestos in aerosol, its mineral and disperse composition. Data on the degree of dusting in the plant for the period 1960--1976 were analyzed and summarized. Professiograms were elaborated, with chronometry and appraisal of the burden of the work operations. All workers were tested clinically and roentgenologically. The data obtained on the degree of dusting in the different departments were re-calculated as amount of inhaled asbestos, depending on how hard the work is, resp. the pulmonary ventilation. The actual risk of asbestos injury was highest in the carding department, followed by the preparatory and the spinning departments. A distinct correlation exists between the degree of professional risk, determined by the asbestos contaminations, and the clinical and laboratory findings.