The Relative Toxicity of PM2.5

• In Event: Innovating Air Pollution Governance: Collaborations, Interruptions, and Regenerations

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 include emissions from combustion, such as power generation, domestic heating and vehicle engines. 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 and mixtures.

Taking the relative toxicity of PM2.5 as a starting point, the paper draws on the author’s ethnographic and collaborative work with public and clinical health, computer science and sociological studies of air pollution. The research comprising this ethnographic study attempts to empirically describe personal particle exposure and human health in spatio-temporally specific (‘micro-environments’) and socio-culturally attentive (‘lived experiences of environmental health’) ways. Particles are also materialised differently in these interdisciplinary projects, making the liveliness of particles an ethnographic tool for interrupting and interfacing environmental health knowledges. The paper ends by considering how exposure science might be more attentive to, and effective in, approaching its translational challenges.

Author

• Emma Garnett, King's College London