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Security requirements when working on personal computers. Occupational Safety and Health

Occupational Safety and Health / Legislative basis for labor protection

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Currently, personal computers (PCs) are widely used in educational institutions in the educational process.

Dangerous and harmful production factors when working on a PC:

• PC as a direct source of electromagnetic and electrostatic fields, and in some cases X-rays;
• negative factors arising from the perception and display of information from the display screen and affecting vision;
• non-compliance of the environment (lighting, microclimate, room coloring, excessive noise, vibration, etc.) with the physiological needs of the human body;
• inconsistency of the workplace with the anthropometric data of the PC operator;
• monotony of work.

These factors cause increased fatigue, memory impairment, headache, trophic diseases, sleep disturbance, pain in the wrists and fingers, as well as in the lower back.

Harmful effects when working on a PC:

• ultraviolet and infrared radiation;
• electromagnetic radiation;
• x-ray study;
• static electricity;
• glare and shimmer.

The design of the PC should provide the ability to rotate the display case in a horizontal and vertical plane with fixation in a given position to ensure frontal observation of the display screen. The design of the PC should include painting the case in soothing soft colors with diffuse light scattering. The PC case, keyboard and other blocks and devices must have a matte surface with a reflectance of 0,4-0,6 and not have shiny parts that can create glare. The design of the display must provide for the regulation of brightness and contrast. The area per one workstation of a PC user should be at least 6 m2, volume - at least 6 m3.

The optimal combination of temperature, relative humidity and air velocity creates comfortable working conditions. The air temperature in the office should be within 19-21°C, relative air humidity within 62-55%. Before the start of classes and after each academic hour, cross-ventilation of the office should be carried out. Every day it is necessary to carry out wet cleaning, and wipe the screens of video monitors from dust. Glass, window frames and fixtures should be cleaned at least twice a year.

Requirements for the microclimate at the workplace equipped with a PC:

• air temperature, ° С ..... 21-25
• relative air humidity, %.....40-60
• air speed, m/s.....0,1
• temperature difference at the floor level and at the level of the seated operator's head, °C..... no more than 3

Premises in which video displays are installed must have natural and artificial lighting. Windows in rooms where computer equipment is used should mainly be oriented to the north and northeast. Artificial lighting can be both general and combined. Illumination on the surface of the table in the area where documents are placed should be 300-500 lux. Local lighting fixtures may be used to illuminate documents. Workplaces should be placed in such a way that the monitor is oriented sideways to the light openings, and natural light falls mainly on the left (Fig. 6).

Fig.6. The location of the workplace with a PC in relation to the light openings 1 - door, 2 - operator's chair, 3 - desktop, 4 - windows

Glitter is eliminated by rational placement of workplaces and the choice of an appropriate lamp. Luminaires for local lighting must have a non-translucent reflector with a protective angle of at least 40°.

It is necessary to adjust the position of the lamp so that there is no glare on the monitor screen. Periodically, the brightness of the screen should be adjusted, if necessary, checking it with a special device (luminance meter). The level of artificial lighting should be checked regularly with a luxmeter.

In the premises of all educational institutions where PCs are located, noise and vibration levels should not exceed the permissible values ​​established by the current sanitary and epidemiological standards for residential and public buildings (Table 2).

Table 2. Permissible values ​​of sound pressure levels in octave frequency bands and sound level generated by PC (SanPiN 2.2.2/2.4.1340-03)

The permissible noise level when working on a PC without a printing device (printer) is 50 dB, with the printer turned on - 75 dB.

The printing device is mounted on a sound-absorbing surface autonomously from the workplace of the PC operator.

Noisy equipment (printing devices, servers, etc.), whose noise levels exceed the normative ones, should be located outside the premises with a PC.

Premises where workstations with a PC are located must be equipped with protective grounding (zeroing) in accordance with the technical requirements for the operation of a PC. PC grounding is mandatory.

Before connecting a PC, check:

• serviceability of connectors;
• absence of kinks and damage to the insulation of wires; no open live parts.

First, plug the power cord into the system unit and only then into the network. It is necessary to provide free access to the socket into which the PC is turned on.

The floor surface in the office should be flat, without potholes, non-slip and easy to clean, with antistatic properties. The walls of the office should be painted in cool colors: light blue, light green, light gray. The use of shiny surfaces in the interior decoration of the office is not allowed. It is forbidden to use polymeric materials (particle boards, laminated paper plastics, synthetic carpets, etc.) that emit harmful chemicals into the air for interior decoration. The windows should have curtains (blinds) matching the color of the walls that do not let in natural light and completely cover the window openings. Black curtains are not allowed. All information on the walls must be covered with a film. Chalk boards are not allowed in the office.

When placing workplaces with a PC, the distance between desktops with video monitors (in the direction of the rear surface of one video monitor and the screen of another video monitor) must be at least 2 m, and the distance between the side surfaces of video monitors must be at least 1,2 m.

The video monitor screen should be at a distance of 600-700 mm from the user's eyes, but not closer than 500 mm, taking into account the size of alphanumeric characters and symbols. Protective filters are mandatory for PCs that do not have a hygiene certificate. Full protection class filters are recommended.

The design of the desktop should provide optimal placement on the working surface of the equipment used, taking into account its quantity and design features, as well as the nature of the work performed. It is allowed to use work tables of various designs that meet modern ergonomic requirements. The desktop surface should have a reflection coefficient of 0,5-0,7. The height of the table surface for adult users should be adjustable within 680-800 mm, in the absence of such a possibility, the height of the working surface of the table should be 725 mm. The modular dimensions of the working surface of the PC table, on the basis of which the structural dimensions should be calculated, should be considered: width 800, 1000, 1200 and 1400 mm, depth 800 and 1000 mm with an unregulated height of 725 mm.

The work table must have legroom at least 600 mm high, at least 500 mm wide, at least 450 mm deep at the knees and at least 650 mm at the level of the outstretched legs.

The design of the work chair (chair) should ensure the maintenance of a rational working posture when working on a PC, allow you to change your posture in order to reduce static tension in the muscles of the neck-shoulder region and back to prevent the development of fatigue. The type of work chair should be chosen taking into account the height of the user, the nature and duration of work with the PC. The work chair must be lifting and swivel, adjustable in height and angle of inclination of the seat and back, as well as the distance of the back from the front edge of the seat. At the same time, the adjustment of each parameter should be independent, easily carried out and have a reliable fixation. The surface of the seat, back and other elements of the chair should be semi-soft, with a non-slip, slightly electrified and breathable coating that provides easy cleaning from dirt.

The design of the work chair should provide:

• width and depth of the seat surface not less than 400 mm;
• seat surface with rounded front edge;
• height adjustment of the seat surface within 400-550 mm and tilt angles forward up to 15° and back up to 5°;
• the height of the supporting surface of the backrest is 300 + 20 mm, the width is not less than 380 mm and the radius of curvature of the horizontal plane is 400 mm;
• backrest tilt angle in the vertical plane within +30°;
• adjustment of the backrest distance from the front edge of the seat within 260-400 mm;
• fixed or removable armrests with a length of at least 250 mm and a width of 50-70 mm;
• adjustment of the armrests in height above the seat within 230 + 30 mm and the internal distance between the armrests within 350-500 mm.

The workplace of the PC user should be equipped with a footrest with a width of at least 300 mm, a depth of at least 400 mm, adjustable in height up to 150 mm and in the angle of inclination of the supporting surface of the stand up to 20°. The surface of the stand must be corrugated and have a 10 mm high edge along the front edge.

The keyboard should be placed on the table surface at a distance of 100-300 mm from the edge facing the user, or on a special height-adjustable work surface, separated from the main tabletop.

For teachers of secondary and higher educational institutions, teachers, the duration of work in display classes, in the classrooms of informatics and computer technology is set to no more than 4 hours a day; for service personnel, it should not exceed 6 hours a day.

Sufficiently strict restrictions on the duration of work have been introduced for students in schools and secondary educational institutions, as well as for students.

The duration of students' work in the classroom using a PC is determined by the course of study, the nature (data entry, programming, program debugging, editing, etc.) and the complexity of the tasks performed.

For first-year students, the optimal time for training sessions when working with a PC is 1 hour, for senior students - 2 hours with the obligatory observance of a break of 15-20 minutes between two academic hours of classes. It is allowed to increase the time of training sessions with a PC for first-year students up to 2 hours, and for senior students up to 3 academic hours, provided that the duration of training sessions in the display class (audience) does not exceed 50% of the time of direct work on a PC, and subject to preventive measures - exercises for the eyes, physical education minutes and physical education breaks.

Mandatory activities for overwork prevention are:

• performing exercises for the eyes every 20-25 minutes of work at the PC;
• organization of breaks after each academic hour of classes, regardless of the educational process, lasting at least 15 minutes;
• cross-ventilation of rooms with a PC during breaks with the obligatory exit of students from it;
• performance during exercise breaks of physical culture pause for 3-4 minutes;
• performing physical exercises for 1-2 minutes to relieve local fatigue, which are performed individually when initial signs of fatigue appear;
• change of sets of exercises once every 2-3 weeks.

Physical culture breaks should be carried out under the guidance of a physicist, teacher or centrally with the help of information on local radio against the background of moderately pleasant music.

Authors: Volkhin S.N., Petrova S.P., Petrov V.P.

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