Cities, as places of social interactions and human relationships, face new challenges, problems, and threats, which are sources of stress for residents. An additional cause of stress in recent years has been the COVID-19 pandemic; it was urban dwellers who were most exposed to the virus and most affected by it. Chronic stress has led to the serious erosion of physical health and psychophysical well-being among urban dwellers, and so there is a need to seek new solutions in terms of building the resilience of cities and their residents to stress. This study aims to verify the hypothesis that greenery reduced the level of stress among urban dwellers during the pandemic. The verification of this hypothesis was achieved based on a literature analysis and the results of geo-questionnaire studies conducted involving 651 residents of Poznan—among the largest of Polish cities, where the share of green areas in the spatial structure is more than 30%. According to the analysis, the interviewees experienced above-average stress levels that went up during the pandemic, and the source was not so much the virus but the restrictions imposed. Green areas and outdoor activities helped in reducing this stress (being surrounded by and looking at greenery, garden work, or plant cultivation). Residents perceive a post-pandemic city as one that is more green, in which priority is given to unmanaged green areas. It has also been pointed out that a response to the reported need for urban re-construction towards stress resilience may be a biophilic city.

Plastic pollution is becoming an increasingly serious threat to the natural environment. Macroplastics, primarily polyethylene films, pose significant ecological and economic risks, particularly in the agricultural sector. Effective monitoring of their presence is necessary to evaluate the effectiveness of mitigation measures. Conventional techniques for identifying environmental contaminants, based on field studies, are often time-consuming and limited in scope. In response to these challenges, a study was conducted with the primary aim of utilizing unmanned aerial vehicles (UAVs), multispectral cameras, and classification tools to monitor macroplastic pollution. The model object for the study was an industrial compost pile. The performance of four object-oriented classifiers—Random Forest, k-Nearest Neighbor (k-NN), Maximum Likelihood, and Minimum Distance—was evaluated to effectively identify waste contamination. The best results were achieved with the k-NN classifier, which recorded a Matthews Correlation Coefficient (MCC) of 0.641 and an accuracy (ACC) of 0.891. The applied classifier identified a total 37.35% of the studied compost pile’s surface as contamination of plastic. The results of the study show that UAV technology, combined with multispectral imaging, can serve as an effective and relatively cost-efficient tool for monitoring macroplastic pollution in the environment.

This article analyzes the correlation between the city size, population density and character of three Polish cities and the following aspects: (1) inhabitants’ subjective stress level and its change during the COVID-19 pandemic, (2) sources and effects of their stress during the pandemic, (3) ways of reducing stress by residents and the role of greenery in this respect and (4) directions of changes in the structure of post-pandemic cities desired by their residents. The main research method was geo-surveys, the results of which were developed using statistical analysis and GIS methods. On the basis of the constructed scale, respondents subjectively assessed the level of experienced stress and its change during the COVID-19 pandemic. The research shows that none of the considered features of cities (including size measured by the number of inhabitants) are related to the level of pandemic stress of their inhabitants. All of them, on the other hand, are correlated with the directions of urban spatial development desired by the residents, conducive to stress reduction. Furthermore, the size of the city and its character affect the subjectively perceived change in stress levels during the pandemic (compared to the stress level before pandemic). Some of the effects of pandemic stress and ways of reducing it depend on the character of the city. The stress experienced by the inhabitants is the lowest in cities with the largest share of green areas in the spatial structure (especially with forest complexes and naturally shaped areas of river valleys), where an effective system of greenery has been adopted (the Howard’s garden city model), and at the same time with dominant single-family housing. The research results were used to indicate new directions for shaping post-pandemic cities that are more resistant to stress and thus healthier for their residents.

The greenery and water structure, in the form of wedges cutting into the city, is a characteristic and unique element of Poznań’s urban model. Already before the Second World War, it became the matrix setting the framework for spatial and natural connections within and around the city. These areas were originally clearly demarcated and formed an organic network that permeated the built-up areas. It was this local network of linkages that was to have the greatest impact on the quality of urban living, climate improvement, biodiversity and the functional and spatial structure of the city. In the idea of the socialist city, ensuring access to green spaces for the masses, was one of the essential policy elements of the time. However, over time, in the various models of the city proposed by successive planners, these interconnections began to disappear and the individual bands were narrowed and sometimes discontinued altogether. This study aims to verify the urban planning models of the city of Poznań against the original idea of a wedge-ring system of greenery and water areas, before and after the political transformation in 1989. How does this original structure function today and how have the socio-economic changes that followed the fall of communism affect the greenery and water solutions proposed in the new city model? A comparative analysis of changes in green and water structure in the different spatial models of the city of Poznań, before and after the political transformation, makes it possible to observe the pace and directions of these changes. The analysis was based on the findings of the then-current master plans and on the studies of spatial development conditions and directions, which are an expression of the city’s spatial policy. It can be used to verify the assumptions made or even to change the current model of the city.

Long-lasting (chronic) stress leads to many adverse effects in living organisms. In this study, the city is perceived as an organism. Thus, the recognition of physiological mechanisms of stress response and coping with it in an organism will help identify and develop similar defence mechanisms in urban organisms. This study proposes a multidisciplinary approach and is aimed at applying the stress response mechanisms of living organisms to cities in order to build stress resilience in case of threat. The long-term impact assessment effects of the COVID-19 pandemic and the restrictions and lockdowns introduced are of particular interest. In the review, we present a theoretical, multidisciplinary approach to building a stress-resilient city suitable for academics and a global audience, and propose concrete strategies for city policymakers to cope with stressors at the level of its inhabitants as well as regulations and management. Mitigation, re-construction, and new urban governance have been recognised as such strategies and likened to shortand long-term stress responses of living organisms. Thus, we have offered policymakers a solution for building a resilient city. A novel model of environmental governance, propositions of intervention, and recommendations have been created that could be used by local city authorities to rebuild citizens’ resilience in post-pandemic times.