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Theme № 12. Value of solar radiation.
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THEME № 12. VALUE OF SOLAR RADIATION.
HYGIENIC REQUIREMENTS TO ILLUMINATION (LIGHTING).
Hygienic value of solar radiation.
All organic life on the Earth is obliged by the existence of energy of the Sun - unique external source of heat and light.
COMPOSITION OF SOLAR RADIATION (In SPACE)
| Wavelength | IRRADIATION |
| > 1000 m | Long-wave |
| 100 – 1000 m | Middle-wave |
| 1 cm – 100 m | Short-wave |
| 100 microns - 1 cm | Microwave |
| 1500 – 4000 nanometer (nm) | IR infrared (long-wave part) |
| 760 – 1500 nm | IR infrared (short-wave part) |
| 400 – 760 nm | Visual light |
| 290 – 400 nm | UV ultraviolet |
| 1- 100 nm | X-ray |
| < 1 nm | Gamma irradiation |
On border of atmosphere voltage of solar radiation is on the average 2 cal / sm2 minute, it is named " solar constant" (depends on activity of the Sun, astronomical factors).
Due to absorption, dispersion and reflection solar beams in atmosphere there are quantitative and qualitative changes of solar radiation:
а) Quantitative - surface of the Earth achieves only 43 % solar constant (depends on geographical position, height of the Sun above horizon, cleanliness of atmosphere).
b) Qualitative changes in spectrum of solar radiation:
On border of atmosphere ultraviolet beams (UV) - 5 %, seen light - 52 %, infrared beams (IR) - 43 %.
Composition of sun light at a surface of the Earth:
UV - 1 %, seen light - 40 %, IR - 59 %
The reason of these changes - 2 screens:
а) electro-magnetic field of the Earth,
b) ozone layer - rejection short-wave beams and delay long-wave part of solar radiation.
Solar starvation.
At lack solar irradiation at people develops the original pathological condition - solar starvation - asteno-vegetative syndrome, oppression CNS, decrease adaptable opportunities of organism. At children may be rickets. The main reason of development this condition it is lack of UVR.
The reasons development solar starvation:
- Insufficient stay on open air – lack solar irradiation in rooms, because window glass detain 35-90 % of solar stream.
- Climatic and geographical conditions of district - Far North - polar night (6 months there is no Sun), very cold weather – children can not stay on open air.
- In Europe lack of solar irradiation at the agricultural population tests 2 months in one year, urban population - 4 months (high level of air pollution),
- Pollution atmosphere - light exposure is reduced on 40-50 %, is especial UVR - in the center of London level UVR in 36 times below, than in suburbs.
- Professional features - miners, submariners etc.
Prevention solar starvation:
1) The greater stay on open air - correct mode of day in children.
2) Correct layout inhabited quarters and buildings (distance from each other), observance norms natural illumination in premises (rooms).
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3) Struggle against pollution of atmosphere.
The most effective way prevention solar starvation is using preventive UVR in special fotaries with luminescent UV lamps in mines, on Far North, for children during possible solar starvation.
Before giving course of UV radiation it is need to define biodoze UVR for concrete person, because it is different for everybody.
Biodoze UVR and it definition.
It is the minimal time UVR causing on a not sunburn skin small erytema (reddening skin) in 8-20 hours after UV irradiation. Minimal daily preventive doze of UVR - 1/8 part of biodoze, optimum (treatment rickets) doze - 1/2-1/4 biodoze.
SPECTRAL DISTRIBUTION AND BIOLOGICAL ACTIVITY PARTS
OF SOLAR RADIATION
| Kind of radiation | Wavelength | Mechanism | Biological effects |
| Infrared | 20000 – 760 | Thermal | Heating tissues, intensifying metabolism |
| Visual | 760 – 400 | Thermal, weak photo- chemical | Sensation light, Tonization CNS |
| Ultraviolet: Range A Range B Range C Range D | 400 – 180 400 – 315 315-280 280 – 180 285 – 265 | Photochemical | Formation Melanin Bactericid, Erytemic Synthesis vitamin D in skin Fluorescent effect |
Ultra-violet (UV) beams.
Most biologically important part of solar spectrum - UV - beams. Length of wave is 10-400 nanometer. The mechanism of action - photochemical effect - at hit in a skin - formation biologically active substances (histamine, holin, acetylholin, etc. ) - photochemical erytema at skin (attributes - precise borders, then – formation melanin).
Kinds of biological action UVR:
- sunburnt (formation melanin), fluorescent - area A 400-315 nm
- erytemic, bactericidal - area B 315-280 nm
- luminescent + strengthening of the previous effects - area C 280-20 nm
- anty-rickets - area D 285-265 nm.
In optimum dozes UV renders strengthening effect, stimulates growth and regeneration fabrics, improves metabolism, functions endocryn, immune system.
At big dozes UVR (sharp action) – fotoerytema, dermatitis, burns, rise temperature of body, fotoophtalmya. At chronic action big dozes UVR - deterioration state of health, decrease serviceability, aggravation chronic diseases, risk factor of cancer of skin - in southern areas melanomas skin in population in 4-5 times is more often, than in the North territories.
Seen light.
Length of wave 400-760 nm, has small photochemical effect - fotosensibilisation action on visual elements in a retina of eye. There is small thermal action - braking quantums of light in fabrics.
Stimulates CNS through excitation the visual center, renders positive influence on emotional condition of the person, function cardiac system and other systems.
At excessive intensity may be blinding action down to destruction photosensitive elements and development retynitis - inflammations of retina.
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