[Limits in the use of cobalt filters for protection against infrared radiation]. / Ograniczenia w stosowaniu filtrów kobaltowych do ochrony przed promieniowaniem podczerwonym.

Cobaltic filters are widely used to protect eyes against infrared radiation. They absorb a greater part of the incident on the filter radiation. The radiation absorbed by the filter enhances its temperature and thus increases infrared radiation regenerated by the filter. This paper describes the study of the effect of Tk cobaltic filter exposed to infrared radiation in the range from 500 W/m2 to 3000 W/m2 on the quantity of infrared radiation regenerated by the filter. The results of the study show the increase in the filter temperature depending on the filter irradiance and the exposure duration. In the case of the filter exposure to irradiance of 3000 W/m2 lasting longer than 10 min the filter temperature may go over 120 degrees C. Radiation regenerated by such a filter reaches about 1250 which exceeds the safe value for ocular exposure. On the basis of the results obtained the conditions for protecting eyes against infrared radiation by cobaltic filters are described.

[Methods for in vivo measurement of light transparency in the human crystalline lens]. / Metoda wyznaczania przezroczystosci soczewek ludzkich in vivo.

A method for the in vivo measurement of light transparency of the human crystalline lens, based on the measurement of the blue and red light threshold radiance, in presented. The threshold limit values for radiances of 477 nm (blue) and 620 nm (red) were measured for people at age from 17 to 66 years old without cataract. The people recognised the geometric figures by left and right eye separately, after being adapted to darkness. The radiance of the figures was changed smoothly by ADM adaptometer. The threshold limit values were measured several times for each eye. For each eye the average of the threshold limit values for radiances of 620 nm and 477 nm and their quotient were calculated. Values of these quotients practically did not change for young eyes (to 32 years old) and they decreased for older eyes. These results indicate the increase of the threshold radiance of 477 nm in relation to threshold radiance of 620 nm for older people, and this means the reduction of the crystalline lens transparency for blue light in relation to red one as they grow old. It seems that the reduction should precede the development of cataractous changes and this fact may be used in the diagnostics of precataractous states.

[Influence of low frequency electromagnetic fields on the nervous system]. / Wplyw pól elektromagnetycznych malej czestotliwosci na uklad nerwowy.

The methods present a short review of the literature dealing with non-thermal bioeffect of electromagnetic fields (EMF), mainly of low and extremely low frequency. The main attention is paid to the information about disorders of the nervous system and about epidemiologic studies of brain tumors in the population exposed to EMF. All quoted authors have stressed great difficulties in the right assessment of adverse effects due to EMF's because of their non-specific influence on the biological structures.

[Usefulness of selected psychophysical methods in the evaluation of lighting conditions]. / Przydatnosc wybranych metod psychofizycznych do oceny warunków oswietlenia.

The author examined the frequency of blinking and the position of the near point influenced by practicing a work of considerable visual requirements in various conditions of illumination. It was established that a 7-hours work causes an increase in the frequency of blinking in all the examined persons and receding of the near point in 93 p.c. of subjects. Calculated was the coefficient of correlation and the tangent of the inclination angle of the extent of changes of the measured functions from the logarithm of intensity of the illumination on the work stand. The received coefficients of correlation were -0.08 in case of changes of the near point and -0.63 for the changes of blinking frequency; instead the tangent of inclination angle respectively -0.41 and -122.

[Evaluation of the optical properties of video display terminals]. / Ocena optycznych wlaciwosci monitorów ekranowych.

Video display terminals (VDTs) pose to these operating then professionally risks resulting from optical properties of the screen, lighting conditions and organization of VDT workplaces. The latest Polish VDTs have been tested to determine their ultraviolet and infrared radiation, screen luminance depth and light reflection factors of the casing, key-buttons and documents serving as information sources. The ultraviolet and infrared radiation did not reach a health-hazardous level, however the light reflection factors were highly differentiated and showed unsuitable distribution inside the operator's visual field; the luminance pulsation of the screen exhibits a considerable depth. The findings promoted defining some rules of the proper use of VDTs.

[Effect of directed infrared radiation on the skin and eye of rabbits after acute and chronic exposure]. / Wplyw kierunkowego promieniowania podczerwonego na skóre i narzad wzroku królików w wyniku ostrego i przewleklego narazenia.

The establish a threshold dose, an acute experiment was carried out by 30 min. radiation of the rabbit's shaved head with all ranges of infrared, 200 W/m2, 350 W/m2 and 500 W/m2 intensities. Irradiation was prolonged up to 2 hrs. Having established the threshold dose, a chronic (5 months') experiment was carried out, irradiating 9 rabbits' skin (in 3 groups) with 350 W/m2 intensity in the range of all three bands. Similarly, tests on the eye transparent part were performed, irradiating only one eye, the other being handled as the control. The results show that the 350 W/m2 intensity of IR-A and IR-C radiation induces a slight erythema on rabbits' skin under long-lasting radiation, and under all radiation ranges no changes in the eye transparent part result at the 350 W/m2 intensity for the IR-A band and 200 W/m2 for the IR-C band. On the other hand, when irradiating the eye with the IR-B band at the 350 W/m2 intensity, slight infiltrations and defects of the eyeball cornea were found. Temporarily, the 350 W/m2 value for human skin was suggested as the TLV for the directional radiation intensity within IR-A and IR-B. On the other hand, for the eye transparent part the following TLVs have been suggested: for the IR-A band--250 W/m2, for the IR-B--150 W/m2, for the IR-C band--150 W/m2. Those values do not refer to laser radiation and do not guarantee the development of cataract under many-years' exposure.