Observing, measuring and tackling air pollution with citizens and elected officials: the case of public policy and technical democracy about particulates matter issue in Montpellier, France.

In the context of a double democratic and environmental crisis, participatory/collaborative action-research has multiplied in recent years with increased attention from institutions. Over the last ten years, many participatory research projects have taken up the democratic and environmental crises by proposing an emancipatory normative scheme to improve public participation and the effectiveness of environmental action.

Our paper presents the first results of a participatory science project, BREATHE, funded by the ANR. It aims to articulate two components : (1) a participatory measurement of fine particulate matter (PM) concentration (PM 10 - PM 2.5 - PM 1 - PM 0.1) and an identification of pollution sources) from passive filters (plants and sensors) and micro-sensors subject to standardization (2) a component of accompaniment and support of public policies based.

The project is based on a participatory science protocol (Chevalier and Buckles, 2009) based on participation engineering (Dosias-Perla et al., 2020). Our fieldwork covers three targets: (a) the incinerator (waste recovery center) - (b) a highways around a small town; (c) a street canyon, city of Montpellier, south of France. On the metrological level, the project aims at analyzing the implication and the effects of the Citizen Science device aiming at "co-constructing" at micro-scales a fine cartography of fine particles concentrations while discriminating the source and modeling the dispersion phenomena. On the political level, the project aims on the one hand to analyze the institutionalization process of the device and on the other hand to analyze its effects on the "co-production" of public policies and strategies through different regulatory frameworks (EPZ, PCAET, Mobility Plan, etc.).

We will also discuss the limits and contributions of this type of interdisciplinary and participatory approach aiming at acting on pollution with and for society. We will present current results and first analyses concerning the complex intertwining of technical and political issues related to air quality metrology, the importance and difficulties of standardizing measurement and of truly developing metrology at relevant scale levels when it comes to supporting public action and addressing health issues