Psychological and physical problems in underground

I found very good text about the problems in the underground:
Psychological and Physiological Effects in Underground Space
By Tetsuro Esaki

Some sections of the text:

People get physically used to working underground, psychological problems remain sensitive.

'In another study of Swedish workers in underground factories, there were initial complaints of fatigue, headache, impaired vision, and general depression. When inadequate lighting, ventilation, and inappropriate color schemes were improved, however, the complaints stopped'

'Adjectives most associated with the underground spaces were "unpleasant, dangerous, musty, dark, smothering, unfriendly, gloomy, and isolating." By contrast, the adjectives least associated with the underground were "relaxing, attractive, open, interesting, cheerful, warm, inviting, stimulating, secure, and silent."'

'Long dark tunnel entrances reinforced negative feelings, and artificial windows to improve the tunnel were disliked. Generally, most people disliked working underground and were unsatisfied with their jobs. They wished for sunlight and greenery and noticed the unusual smells underground. Most workers feared illness from the conditions and expressed concerns over their safety in fire, flood, earthquake, or structural collapse.'

'Workers surveyed in an underground office, subway station, shopping center, and security center reported high levels of anxiety over isolation from the outside and their physical health. Some anxiety was expressed over mental stress and earthquake or fire. The most dominant complaints were: bad air quality, lack of knowledge about the weather, an oppressive feeling, and low ceilings (even though they were the same as comparable above-grade settings).'

'It is interesting to note that while these workers were negative about the underground setting, they would continue to work there if conditions in the physical environment were improved - in particular, if sunlight, plants, surrogate windows, spaciousness, and more ventilation were provided. They also included a greater willingness to work there if they were compensated financially.'

'The lack of windows in buildings above and below grade seems to contribute to the majority of negative attitudes and associations (i.e., claustrophobia, lack of view, natural light, stimulation, and connection to nature). Underground buildings, however, seem to elicit an additional set of negative associations not entirely attributable to lack of windows (i,e., disorientation, coldness, high humidity, poor ventilation, lack of safety, and various cultural and status associations discussed in the previous section)'

'Potential Psychological Problems Associated with Underground Space

1. Because it is largely not visible, an underground building is likely to lack a distinct image.
2. Because there is no building mass, finding the entrance can be difficult and confusing.
3. The movement at the entrance is usually downward, which potentially elicits negative associations and fears,
4. Because the overall mass and configuration of the building is not visible and the lack of windows reduces reference points to the exterior, there can be a lack of spatial orientation within underground facilities.
5. Because there are no windows, there is a loss of stimulation from and connection to the natural and manmade environments on the surface.
6. Without windows to the exterior, there can be a sense of confinement or claustrophobia.
7. In underground space, there are associations with darkness, coldness, and dampness.
8. Underground space sometimes connotes less desirable or lower status space.
9. The underground is generally associated with fear of collapse or entrapment in a fire, flood, or earthquake.'

'SUMMARY OF PROBLEMS
It is interesting to note that these potentially negative effects are all related to one of three basic physical characteristics of underground buildings:

1. lack of visibility from the exterior,
2. lack of windows, and
3. being underground.

Lack of visibility from the exterior causes the lack of a distinct image and the inability to find the entrance, while it contributes to a lack of spatial orientation inside the building since the overall configuration cannot be easily understood.
The absence of windows causes a sense of confinement, lack of stimulation and connection to the outdoors, and lack of sunlight. The windowless nature of underground buildings also contributes to lack of spatial orientation since reference points to the exterior are missing, which is related to a fear of not being able to escape in an emergency.
Finally, simply being underground elicits associations with darkness, coldness, dampness, poor air quality, lower status, and fear of collapse or entrapment.'