Today, the majority of human population is living in urban areas. Urbanization and suburbanization is a common phenomenon of the contemporary world which is often linked to various types of pollution, natural degradation, CO2 emissions and spatial inequalities. The continuous growth of urban population results in increased human activity which consists of new constructions, transportation systems and vehicular movement all of which lead to various types of pollution (Steffen et al., 2015).
The way in which urban space is produced and developed affects the lives of urban dwellers who are in constant contact with various types of pollution and chemicals. This article is part of a research that examines how the experiences of people who live and work in polluted environments can be a source of information, and if their perception of pollution in their living environment can be a new way to study the relationship between urban space, pollution and toxicities.
Perceiving pollution via sensorial mapping
Alternative cartographic approaches are an effective way to understand pollution through the perception of urban dwellers. This, because they question the norms and biases in conventional cartographic representations, and often they highlight non-visible spatial inequalities (Harris and Hazen, 2005). Thanks to sensorial mapping, it is possible to imagine new ways to see the city and recognize the complex socio-spatial relationships shaping urban space (Dalton and Stallmann, 2018), especially in the context of polluted urban environments.
In Grenoble’s case study, sensorial mapping has been used to emphasize the spatial dimension of pollution and the way it affects peoples’ movement in the city and their use of public spaces. This approach provided the opportunity to trace the relationship between safety and pollution in the urban space and to draw possible solutions to reduce pollution. Sensorial mapping enabled participants to express their feelings in a creative way, provided important visual representations of pollution in Grenoble and showed the importance of analysing individual experiences of a problem which has a collective dimension.
We conducted an ethnographic research between February and June 2023 through in-depth interviews with 16 participants, all of them living in the city of Grenoble. During the interviews, the participants were engaged in a sensorial mapping exercise in which they were asked to give spatial information about their personal experience of pollution in their neighborhood, as well as in other parts of the city.
The exercise was guided by specific questions on:
- the types of pollution,
- the locations in which it is more or less perceptible,
- its intensity and the psychological or physical effects it has on them.
The sensorial maps collected were analyzed, compared and graphically interpreted into new maps containing additional information. More specifically, the sensorial maps were juxtaposed in order to spatially trace the differences and similarities of the participants’ experiences of the urban space and their perceptions of pollution. New digital maps were created as a derivative of this analysis and comparison of the collected data.
Grenoble in its geographical context
Grenoble is located within the Alpine mountain chain and has a very interesting topography (Fig. 1). Although Grenoble has a flat territory, it is situated at the intersection of three mountain chains: Belledonne, Vercors and Chartreuse (Largeron and Staquet, 2016). Even though there are multiple strategies implemented by the City Council, the Metropole and the Isère Department as well as many citizen initiatives towards sustainability, pollution remains an important issue in the city (Green Grenoble 2022). The most important type is air pollution and the main factors that lead to high levels of air pollution are the natural topography of the area, the industrial activity in the Isére department and the urbanization (Largeron and Staquet, 2016).
Due to the natural topography of Grenoble, air pollution mainly produced from industries in the Isère department, is «trapped» in the valley because of the mountains that surround the city (Largeron and Staquet, 2016). Moreover, the meteorological phenomenon of temperature inversion aggravates the situation when masses of hot air prevent vertical diffusion of air polluants (Aix et al., 2022). Because of the urban sprawl, there is a secondary source of air pollution, the road traffic in the large highways around the main urban area (Largeron and Staquet, 2016). However, according to the measurements of the air quality indicator ATMO Auvergne Rhone-Alpes, in 2021 the levels of air pollution in Grenoble were lower than in the past (Grenoble 2023).
The main sources of air pollution in most urban areas are anthropogenic, such as road traffic, fossil-fuel combustion and emissions from households (Aix et al., 2022). In city of Grenoble, the main polluant concentrations are particulate matter (PM10 and PM2.5) and nitrogen dioxide (NO2) (ATMO Auvergne Rhone Alpes, 2023). Even though air pollution is the most important type of pollution in the city, it highly affects the quality of soil and water as air polluants are deposited on soil and diffused in the water streams (European Environment Agency, 2023). Eventually, noise pollution is also an issue in Grenoble and it is mostly related to transportation and traffic (ATMO Auvergne Rhone Alpes, 2023).
Sensorial mapping analysis
The 16 participants - diverse in gender, age, country or city of origin, length of stay in Grenoble and occupation (Fig. 3) - live in different neighborhoods of Grenoble (Fig. 2) and were asked on how and where they perceive the different types of pollution. Their diverse backgrounds and the fact that they live in different neighborhoods of the city provided with diverse and even contradicting information.
The main differences regarding their perception of pollution were observed between participants who have lived in Grenoble for a long time, and the ones that have been in the city for a limited period, such as international students. For the first group, in some cases, the constant exposure to air pollution has affected their physical and mental health with symptoms suck as tiredness, allergies or shortness of breath. In order to avoid the high levels of air and noise pollution in their everyday life, the participants who live permanently in Grenoble choose to regularly escape in the nearby mountains.
When we have the opportunity on the weekend, we try to go to the mountains.»
Also, the perception of pollution and its intensity appear different between the participants who have lived in rural areas or smaller cities of France in the past, and those who came from cities of Southern Europe or the Global South.
I guess everything is relative when we talk about pollution. I’ve heard that Grenoble is very polluted but it is the fourth city in France for air pollution. Paris is the first but it is much less polluted than any, even a small city, in the north of Italy.»
Compared to my city in Brazil, Grenoble is not noisy.»
However, the majority had similar experiences when it comes to the most important types of pollution and their intensity as well as a common perception of the urban space and how it is affected by pollution. Indeed, air and noise pollution are factors that alter the way they move in the city, which public spaces they visit or avoid.
You can feel air pollution with allergies and you can even see it when you open your window or when you take a walk. You may think it’s fog but it’s air pollution.»
I find that the noise of cars disconnects me from a part of myself. I find it sad and stressful. Of all the types of pollution, this is perhaps the one that affects me the most.»
The sensorial maps created during the interviews focus on the most and less polluted areas of the city according to the participants’ experience. They differentiated the types of pollution with the use of colors and they were encouraged to draw in different ways and express themselves freely on the maps. From the sensorial maps and the interviews, we can see that the most important types of pollution are air and noise pollution (Figg. 5 and 6).
The map on air pollution shows a clear correlation between the main vehicular arteries of the city and the higher levels of air pollution. When it comes to the map of noise pollution, most participants mentioned a strong connection between the intensity of road traffic and the high levels of noise.
On the roads around the city and on the main boulevards it is very noisy.»
For a better understanding of the sources of air and noise pollution and their spatial dimension on the sensorial maps, two new maps were created where the initial information is graphically interpreted in a more synthetic way, relevant to a conventional map of the city (Figg. 7 and 8).
In order to understand the differences and similarities in the spatial perception of pollution between the 16 participants, the sensorial maps were overlapped and a “collective” sensorial pollution map has been created (Fig. 9). This overlapping creates an elaborate representation of their experience in the city and highlights their collective perception of polluted and non-polluted spaces. Most of the drawings focused on the same parts of the city creating a visual density in specific areas on the final collective sensorial map.
The most prominent information on this map is air pollution, and then the green public spaces, considered safe and less polluted. These two contradicting elements have been underscored by all participants on their individual sensorial maps and therefore they stand out in the collective map. Almost all participants agree that they feel very comfortable and safe in parks and green areas. The density of shapes and colors on the left side of the map indicates the perception of higher levels of pollution in the west side of the city, while the right side of the map is more clear, indicating perception of lower levels of pollution.
The following sensorial map (Fig. 10) figures the green public spaces of Grenoble which the 16 participants represented on their individual sensorial maps. The participants choose to visit frequently these specific areas because it’s where they experience less noise, less perceptible air pollution and less heat during the summer months. Additionally, these green public spaces allow them to interact with other people, to take part in community events or activities and to feel closer to nature. This map presents a much more creative and playful use of lines and shapes, especially when compared to the sensorial maps of air and noise pollution in which their expressions are more “strict” and “simple”.
Even though the participants emphasized the importance — and usually lack — of parks in each of their neighborhoods, they most frequently choose to visit the larger green areas located in the north and east side of Grenoble. The reason for this choice is, either the proximity to their homes if they live in the north-east side of the city, or the fact that these green areas are more pleasant and of higher quality than smaller parks. The exclusion of smaller parks from the green spaces representation on the initial maps could well be an expression of the participants’ need and will for larger green public spaces, where noise is significantly reduced due to the dense nature and the absence of streets. In figure 11, the green public spaces which the participants choose to visit are completed by the smaller parks of the city which were not mentioned or noted on their sketches.
According to the participants, the areas that are perceived to be less polluted as well as the most visited green public spaces are located close to the river Isère. The participants’ perception of high levels of air pollution and the green public spaces they most frequently visit are presented in an original map (Fig. 12) highlighting their spatial relation. It is obvious that the most polluted areas are perceived to be located on the west side of the city, near the train station. These neighborhoods are former industrial areas, now being residential and commercial. In the north and east side of the city, the river Isére creates a natural barrier for the built environment and enables the existence of more green spaces. The riverbanks of the east side are pedestrianized areas with a lot of trees while the more touristic riverbanks in the north lead to the Bastille, one of the larger and most visited green areas of Grenoble.
In figure 13, the city is presented fragmented into two parts, considering on the one hand the levels of air and noise pollution, and on the other hand the availability of green public spaces.
There are two main opposing elements: the highly polluted areas (west-south) and the less polluted green public spaces (north-east). Neighborhoods perceived as the most polluted by the participants do not have green spaces in proximity. Even though Grenoble has many green spaces, there is no balance in their spatial distribution which affects the inhabitants’ quality of life, especially in the neighborhoods in the west side of the city. Neighborhoods perceived as the most polluted are also those that present more diversity in terms of the social, economic and cultural characteristics of the inhabitants in comparison to the rest of the city.
There are large parks nearby, you can access nature quite easily and quickly.» (Inhabitant of Île-Vert, a neighboorhood situated on the east side of the city)
We’re usually going for walks near the Isère river where it’s calm.» (Inhabitant of Championnet, a neighboorhood situated in the center of the city)
My calm spot is a small park in my neighborhood which is on walking distance. But to be fair, it’s quite noisy.» (Inhabitant of Saint Bruno, a neighborhood situated on the west side of the city)
Pollution is an issue that affects most urban areas and has negative effects on people’s well-being, physical and mental health and on the natural environment. In order to find solutions and improve the urban environment, it is important to study and understand not only the sources of pollution but also its impacts on the inhabitants. This study shows that the inhabitants’ perception of pollution is an effective tool to better understand the challenges that arise in highly polluted cities and the issues that people face on a daily basis in relation to different types of pollution.
From the sensorial maps’ analysis, we can clearly see that the participants have a common perception of pollution in the urban space of Grenoble. Air and noise pollution affects or even alters the way they move in the city, the places they feel safe or unsafe, and consequently which areas they choose to visit or to avoid.
Data collected from the interviews and from the sensorial maps show that participants agree on the geography of pollution, focusing on the same areas when asked about their representation of pollution, showing a collective experience of air and noise pollution. So, sensorial mapping not only enables the participants to express their personal experience and gives them the opportunity to discuss their concerns on their living environment, but can also provide researchers and professionals with important information about people’s concerns on the issue.
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