Social density is beneficial as long as individuals do not feel overwhelmed by it and experience a sense of control over their immediate surroundings. In psychology this is known as environmental mastery.
The combination of high social density and low environmental mastery increases the likelihood of (chronic) stress experiences and psychopathological symptoms.
In order to avoid social density stress, the integrity of personal territorial boundaries of individual urban dwellers must be guaranteed – regardless of living space and population density. This must be taken into account as a quality feature in both housing construction and urban planning.

Density is one of the advantages of a city. It is the infrastructural prerequisite for cooperation, distribution of responsibilities and efficiency that differentiates urban spaces areas from rural areas. However, social density in particular can also lead to social stress and thus become relevant to human health. Consequently, from a neurourbanistic perspective, density is an ambivalent topic. If density leads to a lack of space and overcrowding, it puts a strain on almost everyone. This phenomenon, which can be traced back to an innate sensitivity that can also be observed in animals, is known as ‘crowding stress syndrome’. High density leads to negative consequences such as withdrawal, reduction of mating readiness and fertility, as well as a weakening of the immune system. In humans, social density primarily has negative consequences when the individual loses control over the living environment (environmental mastery) and feels unable to influence it. Persistent exposure to social density combined with low environmental mastery can lead to chronic stress and consequently to psychological stress, behavioural changes, disorders and even premature mortality.

Social density is one of the key advantages of the city, but it can also lead to health-relevant stress.

Short-term social density – for example in an overcrowded underground train or lift – is usually not relevant to health but can be perceived as burdensome or threatening depending on a number of internal and external variables. Density tolerance is associated with significant cultural differences. Sociology distinguishes between contact cultures and distance cultures. In our culture, an average arm’s Length is generally regarded as a comfortable distance.
Social density is perceived as positive when we choose it ourselves or it is actively sought out (such as in a crowded restaurant or concert hall) or when we are surrounded by familiar people.

Social density is perceived as positive when it is chosen or actively sought out, or when one is surrounded by familiar people.

Sources
1. Alvarado, S.G., et al., Social Crowding during Development Causes Changes in GnRH1 DNA Methylation. PLoS One, 2015. 10(10): p. e0142043.
2. Lin, E.J., et al., Social overcrowding as a chronic stress model that increases adiposity in mice. Psychoneuroendocrinology, 2015. 51: p. 318-30.
3. Proudfoot, K. and G. Habing, Social stress as a cause of diseases in farm animals: Current knowledge and future directions. Vet J, 2015. 206(1): p. 15-21