1. 3- Physical factors

2. Poor ventilation Ventilation is the way fresh air moves into a room or building, and how old and polluted air moves out. Poor ventilation traps moisture in the house, causing dampness and mold.

3. To know if your house has poor ventilation, look for these signs: Moisture collects on windows or walls. Clothing, bedding, or walls grow mold. Bad smells from toilets or sewers stay in the house. Smoke stays in the house from cooking or heating. If you cook with gas and often suffer from dizziness and confusion, this may be a sign of poor ventilation or a gas leak.

4. ARTIFICIAL LIGHT Poor lighting conditions can cause eye strain and irritation as well as headaches and may increase sensitivity to certain contaminants. The position of the light source in relation to both the viewed surface and the eye is critical. For example, light in front of a desk that strikes the surface and is reflected into the eye can create considerable eye strain.

5. The best position of light source is to be behind and to the left of the desk you work on.

6. TEMPERATURE Recommended temperatures typically range from 68°F to 74°F for the winter and from 73°F to 78°F during the summer with the difference being responsive to both variations in clothing and applicable relative humidity. higher temperatures can affect mental acuity. A reduction in mental work capacity has been observed when temperatures exceeded 24°C (75°F). (C=(F-32) *5/9)

7. Activity Calculate the Celsius degree the is equal to 100 Fahrenheit.