1. Good lighting
Good lighting is essential for efficient vision. The factors which determine good lighting are:
1. Sufficiency: It should be sufficient to see an object or the surroundings without strain.
2. Distribution: It must be distributed uniformly in the whole filed of work.
3. Glare: It should not produce glare.
4. Shadows: It should not produce sharp shadows.
5. Steadiness: The source of light must be steady without flickering.
6. Color: It must resemble that of natural light.
2. Best utilization of day light
It can be done by following measures:
1. Orientation of buildings: As far as possible, buildings must be oriented towards north or south. This provides uniform illumination.
2. Removal of obstructions: Obstructions like walls or buildings should be removed.
3. Windows: Windows must be properly planned. They should not be unnecessarily covered with curtains and screens.
4. Interior of the rooms: Ceiling must be white, upper portion of wall should be light tinted and lower portion must be dark.
3. Artificial illumination
It can be done by filament lamps or fluorescent lamps.
1. Filament lamps: They contain a tungsten filament. Light emitted depends on temperature. Accumulation of dust on the bulbs and shades reduces illumination. So they must be cleaned regularly.
2. Fluorescent lamps: They consist of a glass tube filled with mercury vapor. The inside of the tube is coated with fluorescent chemicals. Fluorescent lamps are cool, efficient and economical. Light emitted by them resembles natural light.
4. Biological effects of light
1. Effect on biological rhythms of body temperature
2. Stimulation of melanin synthesis.
3. Activation of precursors of vitamin D.