Berlin Environmental Atlas

09.01 Environmental Justice (Edition 2015)

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Complementary Indicator 5: Socio-spatial Loads Through Light Pollution
(Gabriel, K. et al. 2015)

Artificial light is also a potential load factor. Artificial light at night disturbs the circadian rhythm of the human organism and results in an imbalance of production of different hormones, especially melatonin, which is related to the human day-night-rhythm. Moreover, interfering with this rhythm can lead to a higher breast and bowel cancer risk, which is particularly relevant for shift workers. As a result, the term light pollution was introduced, which refers to the negative impact of artificial light. On the other hand, light also features as a social component. The illumination of outdoor areas at night is generally perceived as positive; illuminated areas are considered friendlier and safer. This double meaning of artificial light at night leads to the question how nighttime illumination is distributed in Berlin.

In order to obtain an answer to this question, it was necessary to determine a reliable overview over the artificial illumination at night. Contrary to what is common when investigating the brightness of cities, satellite images were not used, but another approach was chosen. Based on a flyover from 2010 which covered two thirds of the city area, a geo-referenced mosaic was generated with a resolution of 1 m² which allowed for an area-wide analysis of the city. It is to be noted that only light emitted skywards was captured. Light radiated sidewards, e.g. from the windows of houses, cannot be captured with this method. With the help of this night shot "Berlin at night", it was possible to depict the nighttime illumination at the LEA level. In order to implement this, the "brightness factor" was determined, which had originally been used to determine the brightness of individual types of land use (Kuechly 2012). Here the average brightness value of a land-use type is offset against the overall average value of the city; the resulting brightness value yields a good average value for the illumination situation of a land-use type.

The following proportions of light were found for the city:

Tab. 5: Proportion of the brightness value in the overall brightness of the city for different types of land use
Land-use type Proportion of overall light emission
Streets 31.6 %
Industrial and commercial areas 15.6 %
Public buildings 9.6 %
Block development 7.8 %
City centre 6.3 %
Airfields 3.7 %
Miscellaneous 25.4 %
Tab. 5: Proportion of the brightness value in the overall brightness of the city for different types of land use (Gabriel, K. et al. 2015, modified according to Kuechly, H. et al. 2012)

The same principle was then also applied in order to determine the light pollution in the planning areas (PLAs). Following Table 5, the brightness values of the streets were used for determining local brightness, as these contribute the greatest share of the illumination of the city and also have a uniform, direct influence on the houses and the surroundings of the inhabitants. Moreover, this served to avoid a masking effect, as would have occurred when considering the PLA as a whole. The planning area Waldidyll/Flughafensee, in which Tegel airport is situated, affords an illustrative example. In the night shot, it is one of the most obvious points, but when considering the PLA as a whole, the influence of the airport vanishes due to the far larger share of forest area.

Fig. 7: Distribution of the light density at the level of the planning areas in Berlin (Gabriel, K. et al. 2015)

Using the 3-level evaluation scale employed for the other factors resulted in a seemingly uniform distribution of light pollution within the city. Apart from the PLA "Unter den Linden Süd", all other PLAs are at the medium and lower light pollution level. At the same time, there is a general tendency of higher light pollution towards the city centre.

An investigation regarding a connection with residential areas characterised by social issues did not yield a clear result. Thus, pollution with an excessive share of artificial light at night cannot immediately be related to weaker social classes, but rather seems to be a set of problems that affects the entire inner-city area while being less significant in the outskirts of Berlin.

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