From Big Medical Encyclopedia

LIGHTING — use of light energy of the sun and artificial light sources for providing vision of the world around.

Gigabyte. value O. is defined by the fact that it, providing a possibility of visions, exerts impact on the general tone of the person and a condition of many systems of its organism. Level of visual working capacity, productivity and quality of work, mood and health of the person, comfort of the environment depends on O. Insufficiently good O. causes exhaustion of sight, reduces working capacity, increases operational and street injuries, promotes development of short-sightedness.

The lake shall be rather intensive and uniform, biologically full on spectral structure, provide the correct teneobrazovaniye, not have the blinding effect and not distort color.

For O.'s characteristic such concepts as illumination, a light flux, luminous intensity, brightness and nek-ry others, applied for a gigabyte are used. estimates of types and systems O. (luminosity, brightness, etc.).

Illumination represents the size of the light flow falling on a surface unit. Unit of illumination — luxury (lx) — illumination of a surface of 1 m 2 at hypodispersion on it the 1 lumen light flow. For determination of level of illumination use light meters — the photo-electric devices consisting of a selenic photo cell and a galvanometer.

For a dignity. services are most convenient Yu-16 light meters with ranges of measurement of illumination from 25 to 50 000 lx and light meters of 10-17 type for measurement of small levels of illumination — from shares of luxury to 100 lx.

Luminous intensity is the size characterizing a luminescence of a source in nek-rum the direction and equal to the relation of a light flow to a space angle, in Krom it extends. It is measured in candelas (cd).

Light flux — the power of a radiant energy estimated on the visual feeling made by it.

Unit of a light flow — lumen (lm) — the light flux radiated in a single space angle (steradian) by a point source of light with luminous intensity in 1 candela.

Brightness — the relation of luminous intensity in this direction to the area of a projection of a radiating surface to the plane, perpendicular to this direction. Unit of brightness — candela on square meter (cd/m 2 ) it is measured by subjective or photo-electric bright Mer or is defined by a calculation method. Brightness of a reflective surface is calculated by a formula:


where L — brightness, E — illumination of a surface, ρ — coefficient of reflection of a surface, π = 3,14.

The coefficient of reflection, or albedo, the size characterizing reflective ability of a surface of a subject is measured albedometry — the photo-electric device which is at the same time registering density of the falling and reflected light flow.

The number of lighting — the size of the light energy which fell per acre the surfaces of the lit body.

Luminosity — the size of the full light flow which is let out by a surface unit of a light source is measured in lumens from square meter (lm/sq.m).

Lightness — the dimensionless quantity used for quantitative assessment of distinction between the visual (light) feelings caused by two adjacent one-color surfaces.

Brightness (direct, peripheral, reflected, blinding) — property of the shining surfaces (at an adverse ratio between their brightness, luminous intensity and brightness of surrounding space) to violate conditions of comfortable sight or to worsen contrast sensitivity (visibility) or to have at the same time both of these effect; brightness direct — from the shining surfaces (lamps, windows and so forth) located near the direction of sight; brightness peripheral — from the shining surfaces located far from the direction of sight; the brightness reflected — from the surfaces possessing elements of specular reflection of beams from the shining surfaces towards an eye; the brightness blinding — the brightness breaking visibility.

At assessment of indicators of intensity and O.'s quality their compliance to requirements of existing rules of natural and artificial O. and a gigabyte is defined. to recommendations. Gigabyte. O.'s assessment includes assessment of level of visual acuity, light, contrast and color sensitivity of sight, stability of clear vision, an optical chronaxia, speed of distinguishing, perception of visual information and a number of psychological functions at given O. Chem the light situation is better, that indicators of a condition of sight and working capacity are more near optimal to the level of functioning, the general and visual exhaustion in the course of work is less expressed to those.

Requirements to intensity and O.'s quality depend on the nature of the performed work, and also on a condition of sight and age of the person. Optimum levels of illumination for persons are more senior than 45 years much above, than for young people with normal sight; the blinding brightness of badly screened lamps has an adverse effect on elderly people.

Fig. 1. The graphic representation of a zone of visual comfort at various light sources; on abscissa axis — color temperature in degrees Kelvin, on ordinate axis — illumination (E) in luxury (lx): I \the upper bound of a zone of comfort, II — the lower bound of a zone of comfort: LTBTs — a lamp of warm this world with the improved color rendition, DB — a lamp of this world, LE — a lamp of natural light, LHE — a lamp of cold natural light, LDTs — a fluorescent lamp with the improved color rendition (shooters designated borders of color temperatures of different groups of light sources).

The level O. providing feeling of comfort depends also on type of the used light source; e.g., at the luminescent O. which is characterized by high content of short-wave beams in a range of visible light, comfortable level O. is higher, than at O. filament lamps (fig. 1).

The lake of rooms is carried out by means of natural and artificial light and subdivided into the natural, artificial and combined lighting.

Natural lighting is provided with natural light sources — direct sunshine and a diffuse light of a firmament (from the sunshine disseminated by the atmosphere). The lake is not considered by direct beams of the sun (insolation) owing to the inconstancy at natural O.'s calculations and normalized separately from it. Initial size for natural O.'s characteristic is illumination from a diffuse light of a firmament.

Natural O. as a natural factor is biologically the most valuable view of the Lake. Its action is defined on the person by high intensity of a light flow and the favorable spectral structure combining hypodispersion of energy in the field of visible light, ultra-violet and infrared types of radiations. Long stay of the person in the conditions of insufficient natural O. leads to development of the «light» or «solar» starvation which is shown in disturbance of phosphorus-calcium exchange, in decrease in resistance of an organism to influence of infectious, toxic and other adverse factors of the environment, in increase in incidence, especially at children promotes development short-sightedness (see).

Natural O. is changeable, its intensity and spectral structure depend on time of day and a season of year, from meteorol, conditions (intensity and the nature of cloudiness * albedo of the land surface), the geographic latitude of the place and extent of pollution of free air. Cloudiness of an upper tier of the atmosphere doubles illumination almost, cloudiness of the lower tier reduces illumination by 25 — 38%, storm — for 87%. The albedo of Earth at new-fallen snow makes 81%, at stale snow — 70%, at dry asphalt — 20%, at wet — 5%.

Pollution of the atmosphere in big cities and industrial centers dust, smoke and gases reduces natural illumination by 25 — 40% of willows of considerable degree detains biologically active short-wave part of sunlight.

Assessment and natural O.'s rationing because of its variability are made not in absolute values of illumination, and in relative indicators of coefficient of natural illumination — the relation of natural illumination in the considered point indoors (Ev) to simultaneous value of outside (Han) of horizontal illumination under the open sky without direct sunlight. The Coefficient of Natural Illumination (CNI) is expressed in shares of unit or as a percentage:

KEO = (Ev / Han) • 100.

Influence size KEO the size and the configuration of the room, size and an arrangement of svetoproyem reflecting ability of inner surfaces of the room and the objects shading it. Depending on purpose of the room and an arrangement of svetoproyem of KEO in it it is normalized ranging from 0,1 to 10%. Size KEO is defined by simultaneous measurement of illumination in the set point of the room and outside of the building under the open sky or is calculated by the lighting method considering the land area of the firmament seen from a settlement point, a delay of light by a glazing and covers of svetoproyem, reflection of light indoors and from the resisting buildings. Simpler, but less exact is the geometrical method of assessment of natural O., at Krom only the relation of the glazed area of svetoproyem to the area of a floor — the light factor (LF) is defined. Approximate sizes SK: for living rooms and administration premises 1: 8 — 1: 10; for chambers of BC and sanatoria 1: 6 — 1: 8; for school classes 1: 4 — 1: 6; for operational and drawing halls 1: 2 — 1: 3.

Natural O. is divided by an arrangement of svetoproyem on side, upper and combined, and also on unilateral and bilateral. Side natural O. is carried out through light apertures in outside walls (window), upper — through light apertures in a covering (so-called lamps), combined — through light apertures in walls and in a covering. Unilateral side O. is applied in rooms where irregularity of illumination is admissible nek-paradise and a certain orientation of shadows is useful — in offices, schools, etc. At unilateral O. orientation of svetoproyem is of great importance, edges influences illumination and insolation of the room. At orientation to the North insolation is excluded, but relative constancy of lighting at light one o'clock in the afternoon remains that is rational for operating rooms, studio of artists, but it is irrational for chambers of BC, living rooms, group rooms of child care facilities, etc. Bilateral side O. is applied in rooms with a deep water of laying where there are no strict requirements to an orientation of light and constancy of illumination (e.g., in assembly halls). Upper O. bilateral and «antiaircraft» lamps creates uniform O., favorable conditions for vision in the horizontal and vertical planes and is widely applied, as well as the combined O., at construction of industrial facilities, sports constructions, show rooms, etc.

Natural O.'s norms of rooms are established separate for a side and upper arrangement of svetoproyem. At side O. the KEO minimum value is normalized (in a point of the working surface located at distance of 1 m from a wall, the most remote from windows). In rooms with the upper or combined O. the average value of KEO on a working surface is normalized (not closer than 1 m from walls).

Svetoproyema, in addition to O. of rooms natural light, provide visual communication with surrounding space that is a valuable psychogienic factor, and access to the room of direct sunshine — insolation. Insolation significantly increases illumination and ultra-violet irradiance of the room, renders the revitalizing, bactericidal and positive psychoemotional impact. The existing standards provide 3-hour continuous insolation of residential buildings and the territory of the residential development of the inhabited places in days of an equinox.

For the prevention of excessive insolation during the periods when it leads to an overheat of rooms and has the blinding effect, sun-protection devices of stationary or adjustable type — visors, horizontal and vertical screens, special gardening, transparent curtains and blinds are used. The construction of buildings without natural O. is allowed only in cases special tekhnol, requirements, napr, in need of maintenance in strictly constant temperature and humidity or a particular light status. The construction of buildings with insufficient natural O. of rooms for long stay of people with use of the combined lighting is allowed for those productions where such space-planning characteristics of rooms are necessary, at to-rykh the normalized levels of natural illumination (e.g. cannot be provided, at placement of the large-size equipment in multi-storey industrial buildings of big width, etc.). Natural O.'s lack shall be compensated by high quality of artificial O., and at big deficit of natural light and preventive uv radiation of people (in fotariya or from svetooblu-chatelny installations in production rooms).

Artificial lighting is a necessary condition of continuation of vigorous activity of the person in night-time. It is carried out by means of lighting lamps — light sources with an intensive radiation in the visible range of a range.

The electric lamps generating light radiation due to heating of the shining element — a filament lamp are most widespread; or at the expense of a luminescence of electric discharge in gas independently or together with the luminescence excited by it phosphors (see) — arc, gas-discharge lamps. Electric light sources are favorable in a gigabyte. the relation because they are rather effective, do not absorb oxygen from air and do not pollute the environment products of combustion.

Filament lamps make various power, tension and types, they are compact, simple in use, are reliable, almost independent of conditions of the environment. A lack of filament lamps are: imperfection of a range of their light flow, in Krom yellow-red radiations prevail; the blinding brightness of filament; the small sizes of the shining elements creating big irregularity during the use of single lamps; limited endurance (no more than 1000 hours of burning).

Gas-discharge light sources (see), to the Crimea also fluorescent lamps belong, is more effective than filament lamps thanks to higher light return, bigger endurance (to 5000 hours and more) and a significant area of the shining surface increasing uniformity of the Lake. Use of phosphors allows to receive various range of O., including approximately imitating natural light that is the basic, about a gigabyte. positions, basic advantage of these light sources. Lack of gas-discharge lamps are: complexity of the scheme of inclusion; insufficient compactness; unreliability of work at temperature variations of the environment and tension in network; the lineychatost of a range distorting colors; the pulsation of a light flow (time history of a light flow at food of gas-discharge lamps alternating current) causing stroboscopic effect (the seeming change or the termination of the movement of a subject during the lighting by its light which is periodically changing on intensity with a certain frequency); the increased exhaustion.

Fluorescent lamps are divided into 4 standard types — daylight (LD), cold this world (LHB), this world (LB) and warm this world (LTB) and 4 types of lamps of the class «delyuks» with the improved color rendition — LDTs (daylight with the improved color rendition), L of E (natural light), LHE (cold natural light) and LTBTs (warm this world with the improved color rendition). Lighting fluorescent lamps from an ultra-violet component of a light flow (LDTsUF), and also erythematous fluorescent lamps (LE) and germicidal lamps (DB) making long-wave and short-wave ultraviolet radiation are applied to the special purposes.

At the choice of a light source requirements to O.'s intensity and to a color rendition, external environment of lighting installations and idiosyncrasies of lamps are considered (the pulsing light flux, radiation in ultra-violet and infrared spectral ranges, etc.). In lighting installations of general purpose, to the Crimea special requirements for quality of a color rendition are not imposed (for illumination of big open spaces of sports constructions, airfields, building sites, high-speed highways, tunnels, high-flying workshops, architectural objects), lamps, highly effective on light return irrespective of quality of a color rendition, naira, sodium lamps of high and low pressure, arc mercury-quartz lamps of high pressure, metallic-halogen lamps, and also the powerful xenon lamps having the continuous spectrum of radiation coming to solar can be applied. In public, administrative, educational and similar by it buildings, in workshops with delicate visual work from gas-discharge lamps are applied, as a rule, luminescent, to-rye do not give essential color aberration and a big pulsation of illumination, have no intensive radiation in an ultra-violet spectral range.

Filament lamps remain the leading light source for premises, local and emergency O. Dopustimo use in one room of lamps of different types — for the general and local O., working and emergency O. and in the general O.'s system for the purpose of improvement of a color rendition.

For redistribution of a light flow of lamps and protection of sight against their blinding action of a lamp use in lamps. As sveto-distribution lamps are divided into 5 classes: direct light, the directing 90 — 100% of light of a lamp for the lit surface; preferential direct; scattered; preferential reflected and reflected light (the last more than 90% of light direct up). On a design distinguish lamps of the concentrated and wide light, different degree of protection against dust and moisture, different reactive substances resistance and to physical impacts. Lamps are divided by a way of installation on ceiling, suspended, wall, floor; on stationary and figurative. Ceiling lamps happen single and joined to the line. For creation of especially uniform lighting of the room use the so-called shining ceilings, in to-rykh a lamp evenly have on the area of a ceiling and cover from below with the general lens.

Fig. 2. The diagrammatic representation of lamps with various lamps: and — from transparent glass; — from milk glass; in — with two fluorescent lamps, γ — a protective corner of the lamp.

Protection of sight against the blinding action of lamps is provided by height of a suspension of the lamp and its protective corner — a corner between the horizontal passing through the edge, next to an eye, of the shining element of a lamp and the straight line connecting an extreme point of the shining element to edge opposite to it of the shielding fittings — the lens, a reflector or the shielding lattice (fig. 2). The protective corner of lamps for local O. shall be not less than 30 °.

The special group of lighting fixtures is made by searchlights, in to-rykh by means of optical system of lenses and mirrors light of a lamp for especially intensive illumination of an object concentrates a narrow beam practically without dispersion. Searchlights widely use for O. of open spaces, sports constructions, pits, territories of the enterprises. - of stations and other similar objects, and also for architectural and theatrical lighting.

In searchlights all types of lamps, except luminescent are applied.

Perspective reception of O. is use of light guides — the hollow reflecting designs with system of the lenses or mirrors transferring light from a natural or artificial source to considerable distance. Use of light guides is especially reasonable in vzryvo-and fire-dangerous rooms, in pressures chamber, etc.

On systems of an arrangement of lamps artificial O. of rooms is subdivided into the general uniform, general localized (over jobs) and the rooms combined, consisting of the general O. and local O. of jobs. The device in one local O.'s rooms is forbidden since the big difference in brightness of a workplace and surrounding space leads to the increased exhaustion because of frequent readaptation of sight and insufficiency of illumination of peripheral zones of a retina. Illumination from the general O. in system of combined shall make not less than 10% of total illumination in a workplace.

By types artificial O. is subdivided on working, emergency, evacuation and security. Emergency O. is arranged where shutdown of the worker O. can cause explosion, the fire, poisoning of people, disturbance of the basic tekhnol, process (disturbance of work of communication centers, electro-and water supply, disturbance of service of patients in surgery blocks, delivery rooms, offices of acute management, resuscitation, in places of acceptance to lay down. institutions, and also in child care facilities). Evacuation lighting is arranged on the ways of an exit of people from rooms and buildings and in places of dangerous passes, on the ways of evacuation at sudden shutdown of the worker O.

Security O. provides a possibility of overseeing with order on production objects in after hours.

The combined lighting (at the same time natural and artificial O. of all room or a part of the room with coefficient of natural lighting is less than normalized) is used in rooms with insufficient natural O. V industrial buildings at the combined O. reduction of KEO to level 60 — 30% of norm is allowed: in public buildings, as a rule, it is not lower than 60%, in trading floors of shops, buffets and at distributing catering establishments to 30%. At the combined O. the general artificial O. of rooms shall be carried out by the gas-discharge light sources closest on a radiation spectrum to natural light. In a zone of the room with KEO below norm the increased artificial illumination shall be created. Zones with KEO below the specified minimum values are equated to rooms without natural light.

In rooms without natural light, in addition to increase in level of illumination, increase in a share of the general O. in system combined and use of gas-discharge lamps with an optimum radiation spectrum is provided. O. is recommended to create dynamic conditions, imitating variability of natural light, to eliminate a pulsation of illumination and to enrich a light flux of lighting installations with ultraviolet radiation for prevention of light «starvation».

Artificial O.'s assessment is made by measurement of illumination and brightness, and also a settlement way — on the power of lighting installation (in watts on square meter) taking into account type of lamps, height of their installation and coefficients of reflection of surfaces of a ceiling, walls and a floor), on a use factor of lighting installation in rooms of a different configuration or a point contact method — the most difficult, but allowing to receive the most right result. For convenience of calculations the corresponding tables and nomograms for lamps of various types with filament lamps and with fluorescent lamps are provided in lighting reference books.

By the most widespread and rather exact method of a use factor of lighting installation illumination is determined by a formula:

Е =(Ф*N*η)/(K*S*Z)

Where E — the level of horizontal illumination from the general uniform lighting; F — a light flux of lamps in each lamp; N — number of lamps; η — a use factor of the lamp; To — degree of safety; S — the area of the lit room; Z — the relation of average illumination to minimum, depending on the relation of distance between lamps to height of their suspension. A use factor of the lamp is according to the corresponding table taking into account type of the lamp, a configuration of the room and coefficients of reflection of surfaces of a ceiling, walls and a floor. The whitewashed ceiling, the whitewashed walls with the windows closed by white curtains possess coefficient of reflection, equal about 70%; the whitewashed walls at not curtained windows, the whitewashed ceiling in crude rooms, a pure concrete and light wooden ceiling — 50%; a concrete ceiling in dirty rooms, a wooden ceiling, concrete walls with windows, the walls which are pasted over with light wall-paper, a light floor — 30%; walls and ceilings in rooms with a large amount of dark dust, a continuous glazing without curtains, the red brick which is not plastered walls with dark wall-paper, a dark floor — 10%.

Norms of lighting

the Normalized KEO levels and levels of illumination at luminescent O. are established taking into account the nature of visual work — the sizes of a subject to distinguishing, its contrast with a background, the characteristic of a background and system O. on the basis of a settlement stock of visibility of a subject to distinguishing for young people with normal sight. At limited time of distinguishing of details, need of distinguishing of moving and remote objects, at raised a dignity. requirements to production and in rooms for work and inservice training of teenagers the normalized levels of illumination increase; during the use of filament lamps and in rooms with short-term stay of people — go down. In addition to the kolichestvezzy characteristic of O., norm regulate the main quality indicators of O. - uniformity (the attitude of the maximum illumination towards average or minimum), restriction of the blinding brightness and a pulsation of a light flow, O.'s constancy in use (degree of safety, to-ry represents size, the return to decrease in illumination in use of lighting installation due to reduction of light return of lamps, pollution of lamps, lamps, decrease in the reflecting properties of surfaces of the room, and it is expressed in relative sizes).

O.'s norms of public buildings are established taking into account purpose of the room, complexity and duration of visual work, the applied light sources. The most high levels of KEO and the general O. are normalized for design and design offices (KEO of 2,5%, illumination of 500 lx), administration and educational premises (KEO of 1,0%, illumination of 300 — 400 lx), research and analytical laboratories (KEO of 1,5%, illumination of 400 — 500 lx). Illumination from the combined O. in public buildings is not normalized, except illumination on a blackboard at school (500 lx). In rooms where additional local O. is required, norms provide installation of plug sockets for connection of table and other local lamps. In those public places where it is necessary to create feeling of a saturation light — in conference halls, in reading rooms, in premises of the spectacular enterprises, etc., not only horizontal, but also space («cylindrical») illumination in the vertical plane at the height of 1,5 m from a floor (from 75 to 150 lx) is normalized. In public buildings the indicator of discomfort (the characteristic of quality of O. defining degree of the visual discomfort caused by a sharp difference of brightness of at the same time visible surfaces and depending on brightness of these surfaces, their angular sizes and situation under review) and coefficient of a pulsation of illumination is strictly limited, to-ry is determined by a formula

of Kp = (Emaks - Emin) *100/2esr

where Emaks, Emin, Esr — respectively the maximum, minimum and average values of illumination (E) during its fluctuation, in lx.

On the basis of the general state norms of O. the industry norms considering specifics of specific industries of production and types of public buildings are developed. O.'s norms of production rooms established Construction Norms and Regulations of II-4 — 79, are presented in the table.

In O.'s norms to lay down. - professional, institutions requirements to illumination of all funkts are provided, rooms, and different levels of illumination in offices of doctors of different specialties according to different complexity of diagnostic survey of patients are normalized (e.g., the therapist and the dermatologist or the allergist). For offices of doctors in institutions of polyclinic type higher are normalized, than in hospitals, levels O. (respectively 500 and 300 lx at fluorescent lighting and 200 and 150 lx at O. filament lamps) that is connected with a big flow of patients, limited time of survey and large volume of work of polyclinic institutions in hours with the insufficient natural Lake. High levels of illumination (400 — 500 lx) are normalized in operational, resuscitation rooms, maternity, in laboratories and drugstores. For the majority of rooms to lay down. - the prof. of institutions is recommended luminescent O.'s use on condition of use only of those types of lamps, to-rye provide quality of a color rendition, sufficient for diagnostic work (a lamp of LHE and to them similar).

O.'s norms for houses regulate the minimum KEO of living rooms and kitchens (not less than 0,5%) and the average level of artificial illumination for inhabited and auxiliary rooms of the apartment (50 — 30 lx at filament lamps, 100 — 75 lx at fluorescent lamps), and also for ladders, elevators and other rooms of a house (30 — 10 lx). In the living room in addition to the general O. rekokhmendutsya to arrange additional (local) O. separate funkts, zones — for long occupations (a desk, the place for sewing, etc.), for periodic short-term reading, for meal and rest.

Outside O.'s norms of the inhabited places regulate the level of illumination and brightness of pavings, O.'s uniformity and tolerance level of an indicator went blind-lennosti — the size characterizing the blinding action of lighting installation. Value of an indicator of an osleplennost in relative units is determined by a formula:

P = (S-)) *1000,

where S = (V1/V2) (S — coefficient of an osleplennost; V1 — visibility of a subject to observation during the shielding of blesky light sources; V2 — visibility in the presence of blesky sources under review). Requirements are established depending on category of streets, intensity of traffic. Illumination of sidewalks shall make not less than a half of illumination of a carriageway. Much attention is paid to O. of public and shopping centers, transport tunnels, the territory of inhabited residential districts, parks and other vacation spots. Utilitarian O. of the cities shall be combined with architectural and advertizing O. that creates an evening appearance of the city and the osleplennost from an excessive difference of brightness warns.

Rational O., promoting safety of work, movement and protection of sight of people, shall be safe in operation. It is provided with observance of relevant requirements of technical specifications of release of the lamps and lamps intended for rooms of different function with different conditions of the environment, and also service regulations of lighting installations. During the replacement of the out of service gas-discharge lamps containing mercury measures for the prevention of pollution shall be taken by vapors of mercury of air of the enclosed space.

Table. STANDARDS of ILLUMINATION of PRODUCTION ROOMS (ACCORDING TO Construction Norms and Regulations of II-4 — 79)

Bibliography: Galanin N. F. Radiant energy and its hygienic value, JI., 1969; Gusev H. M. Natural lighting of buildings, M., 1961; Knor r and N of G. M. and d river. The reference book for design of electric lighting, JI., 1976; International lighting dictionary, M., 1979; V. V. Bags iyepaneshnikovm.m. Lighting installations, M., 1972; Parfyonov A. P. Solar starvation of the person, JI., 1963; Rokhlin G. N. Gas-discharge light sources, M. — JI., 1966; The Guide to utility hygiene, under the editorship of F. G. Krotkov, t. 3, page 123, M., 1963; Chernilovsk and I am F. M. Illumination of the industrial enterprises and its hygienic value, D., 1971, bibliogr.; Sheftel E. B. Illumination of medical institutions, M., 1977.

3. A. Skobareva; N. I. Zoz (tab).