[The biological effect of low-frequency noise (cytogenetic and immunologic studies)]. / O biologicheskom deistvii nizkochastotnogo shuma (tsitogeneticheskie i immunologicheskie issledovaniia).

The study revealed that during 3 months noise with the frequency of 31.5 Hz and intensity of 90 dB modified the integrity of hepatocyte chromosomes, activated C-chair and oppressed B-chain immunity of white random-bred male rats aged 3-4 months.

[Methodologic approaches to assessing the noise level of health resorts and places of mass recreation of the population]. / Metodicheskie podkhody k otsenke shumogo rezhima kurortov i mest massovogo otdykha naseleniia.

Methodological approaches to the assessment of noise regime at health resorts and places of rest of the population were set forth when carrying out preventive and current sanitary surveillance. The sources governing the noise regime of health resorts and places of rest were identified, and the problems of zone arrangement of places of rest according to its type (long-term or short-term) analysed. Permissible noise levels were given for various functional zones and the measures for normalization of noise regime proposed.

Intermittent-noise effects and hygienic standards.

Effects of variable equivalent intermittent noises on hearing acuity, peripheral vascular tonus and the latent period of motor responses were studied experimentally. Two-hour exposure to noise in the form of noise intervals of rectangular shape alternating with pause intervals at ratios of 20 :5, 20 :20, 20 :30, 10 :20 and 30 :60 seconds or to nonfluctuating noise was used. In all instances the equivalent level of noise was 80 dB(A). It was found that the degree of biological effect depended on the summary duration of the noise intervals in the total exposure period. A formula for correcting noise-level safety standards in the case of intermittent noises was proposed, viz: (formula; see text) where tau = summary duration of noise intervals and T = exposure time under evaluation. The possibility of using this relation also in evaluating situations where complementary to the equivalent level also the peak level of a given noise is subject to standardization is discussed.