In recent times increasingly found in the production processes, based on the use of ultrasound energy. Ultrasound has also found applications in medicine. In SV’in connection with the growth of individual capacities and speeds of different units and machines are growing levels of noise, including in the ultrasonic frequency range.

The ultrasound is called the mechanical vibrations of an elastic medium with a frequency, exceeding the upper limit of audibility -20 kHz. The unit of measurement of sound pressure level is dB. The unit of measurement of the intensity of ultrasound is the watts per square centimeter (Ut/cm2).

Ultrasound is the main way local effects on the body, because it is transmitted by direct contact with an ultrasonic tool, workpiece or environments, where ultrasonic vibrations are excited. Ultrasonic vibrations, generating a low-frequency industrial ultrasound equipment, affect the human body. Long-term systemic exposure to ultrasound, is spread through the air, causes changes in the nervous, the cardiovascular and endocrine systems, auditory and vestibular analyzers. The most characteristic is the presence of dystonia and asthenic syndrome.

The severity of the changes depends on the intensity and duration of influence of ultrasound and enhanced if the spectrum of high-frequency noise, herewith attached marked reduction hearing. In the case of continued contact with ultrasound these disorders are becoming more stubborn.

When the local effect of ultrasound raises the phenomenon of vegetative polyneuritis of the hands (less legs) varying severity, until the development of paresis of the hands and forearms, vegetative-vascular dysfunction.

The nature of the changes, occur in the body under the influence of ultrasound, dose-dependent effects.

Small doses - the sound level 80-90 dB - give a stimulating effect - the micro-massage, acceleration of metabolic processes. Large doses - the sound level 120 and more dB to give a striking effect.

The basis of prevention of adverse effects of ultrasound on persons, serving ultrasound unit, is hygienic standardization.

According to GOST 12.1.01-89 “Ultrasound. General safety requirements”, “Sanitary norms and rules in the operation of industrial ultrasonic systems” (No. 1733-77) limited to sound pressure levels in the high-frequency region of audible sounds and ultrasounds in the workplace (from 80 to 110 cerebrohepatorenal dB at frequencies one-third octave bands from 12,5 to 100 kHz).

Ultrasound, what is transmitted by contact, normalized “Sanitary norms and rules when working with hardware, which creates ultrasounds, transmitted by contact to the hands working” No. 2282-80.

Measures to prevent adverse effects of ultrasound on human operators of process plants, personnel treatment and diagnostic rooms are primarily in the activities of a technical nature. These include the establishment of automated ultrasonic equipment with remote control; where possible, use low-power equipment, contributing to the reduction of intensity noise and ultrasound in the workplace on 20-40 dB; placement of equipment in the premises zvukolan cabinets with remote control; equipment acoustic devices, covers, screens of sheet duralumin or steel, rubber coated, anti-noise mastic and other materials.

When designing ultrasonic systems it is advisable to use operating frequencies, the most remote from the audible range - below 22 kHz.

To exclude the influence of ultrasound upon contact with liquid and solid environments, it is necessary to establish a system of automatic disconnection of ultrasonic transducers during operations, during which contact is possible (for example, loading and unloading of materials). To protect the hands from contact action of ultrasound is recommended to use special working tool with a handle vbrosa.

If for operational reasons it is impossible to reduce the level of noise intensity and ultrasound to valid values, it is necessary to use PPE - protium, rubber gloves with cotton lining, etc..

The development of equipment and vehicles, improvement of technological processes and equipment accompanied by an increase in output and dimensions of machinery which causes a trend of increasing low-frequency components in the spectra and the appearance of infrasound, that is a relatively new, not fully studied the factor of production environment.

Called infrasound acoustic oscillations with a frequency below 20 Hz. This frequency range lies below the threshold of hearing and the human ear is unable to perceive the vibrations of these frequencies.

Infrasound production occurs through the same processes as the noise audible frequencies. The highest intensity infrasound vibrations create machines and mechanisms, having the surface of large dimensions, what do low-frequency mechanical vibrations (infrasound mechanical origin) or turbulent flows of gases and liquids (the aerodynamic infrasound Il! hydrodynamic origin).

Maximum levels of low-frequency acoustic oscillations from industrial and transport sources reach 100-110 dB.

Study of biological effect of infrasound on the body showed, when the level of 110 to 150 dB more and it can cause people unpleasant sub’objective sensations and numerous reactive changes, which include changes in the Central nervous, the cardiovascular and respiratory systems, vestibular analyzer. There is evidence that, that infrasound causes hearing loss mainly at low and medium frequencies. The intensity of these changes depends on the intensity level of the infrasound and duration of action of factor.

According to Sanitary norms of infrasound at the working places (No. 2274-80) in nature infrasound spectrum is divided into broadband and harmonious. The harmonic spectrum character set in octave frequency bands the level is exceeded in one lane over adjacent not less than 10 dB.

On temporal characteristics of infrasound is divided into permanent and non-permanent.

Normalized characteristics of infrasound in the workplace are sound pressure levels in decibels in octave bands with geometric mean frequencies 2, 4, 8, 16 Hz.

Permissible levels of sound pressure are 105 dB in the octave band 2, 4, 8, 16 Hz and 102 dB in the octave band 31,5 Hz. The total sound pressure level should not exceed 110 dB Lin.

For non-permanent infrasound normalized characteristic is the total sound pressure level.

The most effective and almost the only means of dealing with infrasound is reducing it at the source. When selecting the designs preference should be given to smaller machines high rigidity, because in structures with flat surfaces of large area and low stiffness are created conditions for generation of infrasound. The suppression of the infrasound at the source of emergence must lead in the direction of changing the mode of operation of technological equipment - increase his speed (for example, the increase in the number of working strokes of press-forging machines, to the basic repetition rate of power pulses lay outside the infrasonic range).

Action should be taken to reduce the intensity of the aerodynamic processes - limiting speed of traffic, reduced speed of expiration fluids (aircraft and rocket engines, internal combustion engines, system reset a couple of thermal power plants, etc.).

In the suppression of the infrasound on the specific pathways of the effects of the interference type muffler, usually in the presence of discrete components in the spectrum of infrasound.

Made recently a theoretical analysis of nonlinear flow processes in the absorbers of the resonant type opens a real way of constructing sound-absorbing panels, covers, effective in low frequencies.

As personal protective equipment we recommend the use of headphones, inserts, protecting the ear from adverse action of the associated noise.

Prevention organizational plan should include the compliance regime of work and rest, prohibition of overtime work. In contact with the ultrasound more 50% working time recommended breaks 15 minutes every 1,5 opening hours. Significant effect is a complex physical therapy - massage, Ut-irradiation, water treatments, fortification, etc.