Paper short abstract:

Taking the elemental ambiguity of PM2.5 as its starting point, this paper explores the chemical entanglements of PM2.5 in air pollution research. The author then reflects on the spatial and temporal shaping of exposure by tracing the social and relational chemical life of particles.

Paper long abstract:

This paper explores the chemical entanglements that fine particulate matter (PM2.5) make perceptible in air pollution research. PM2.5 is comprised of particles that are less than 2.5 micrometres in diameter and includes ash and sea-spray as well as emissions from combustion, such as for power generation, domestic heating and vehicle engines. As a heterogeneous pollutant, PM2.5 cannot be individuated or materially defined in any simple way. Further, there is no safe threshold of exposure. What is toxic about PM2.5 is often claimed to be the result of its size rather than chemical composition (fine particles can get trapped deep in the lungs and cause damage. Yet recent studies also reveal the relative toxicities of PM2.5: other forms of difference shape these chemical ontologies, such as local and regional variation, human and atmospheric time and specific emission sources.

Barry (2001) has written that 'air quality' has multiple realities depending on the conditions and circumstances within which it circulates. Taking the elemental ambiguity of PM2.5 as a starting point and drawing on the author's ethnographic work in epidemiological and clinical studies of air pollution, situated material instantiations of PM2.5 will be analysed as 'events' that demonstrate the relational formations of chemical bodies. Considering the social and relational chemical life of particles will enable critical reflection on the spatial and temporal shaping of exposure. Attending to these chemical entanglements instigate new methodological and theoretical tools for understanding and responding to human-non-human lifeworld's and what they demand and oblige of us.