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Justyna Moizard-Lanvin


Contact : justyna.moizard(at)


Dissertation defended on 16 December 2022: A paradoxical fragmentation ? Knowledge and ignorance in the management of air pollution in Paris

Under the supervision of Soraya Boudia (Université Paris Cité) and Maurice Cassier (CNRS)

This dissertation, at the crossroads of the sociology of science and technology studies and the sociology of collective risks, is based on two observations. The first observation is that air pollution is still considered as a major public health problem in spite of recurrent alerts since the 1960s ; the setting up of air quality monitoring and health surveillance structures in Europe and North America ; and the construction of a scientific consensus based on the accumulation of a body of scientific knowledge in epidemiology, toxicology, pneumology, atmospheric physical chemistry, meteorology and metrology. The second observation is the increased role attributed by the WHO and/or claimed by cities in the recent management of air pollution problems. This is manifested by the organization of networks such as the C40 Cities Climate Leadership Group, an international network of so-called global cities that are implementing policies to combat air pollution and climate change in addition to national policies.Based on these findings, this dissertation focuses on the transformations in the definition and management of the air pollution problem in Paris, an active player in the C40 Cities network. It studies how different groups of scientific experts have dealt with the problem of air pollution since the great London smog of 1952. Based on an empirical investigation using different methodologies (interviews, ethnographic observation, analysis of documentary corpus), this dissertation delves into the types of knowledge produced by these experts to support the municipal authorities in dealing with the problem. To account for the results of the empirical survey, this work takes up the concept of "knowledge fragmentation" proposed by Kim and Mike Fortun (2014) to qualify the distribution of knowledge in the field of health and environmental risks. An extension of the "knowledge fragmentation" concept is proposed by considering not only the modalities of knowledge production, but also the effects of this fragmentation. Doing so shows that this fragmentation has two effects, which at first glance seem paradoxical. The first effect is an accumulation of scientific knowledge on exposure to air pollution that does not fully respond to the concerns of general practitioners and citizens' associations regarding the increase in environmental pathologies. The second is the production of blank spaces of "undone science" (Frickel et al. 2010; Hess 2016, 2020) on several aspects of environmental exposures, both on environmental pathologies and on the distribution of social and environmental health inequalities. Finally, this dissertation questions the political effects of this paradoxical fragmentation.

Keywords: Air pollution, Environmental health, Paradoxical fragmentation, Undone science, Ignorance, Environmental pathologies

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