Managing emerging environmental risks when we do not know enough about them: The case of respirable mineral dust

Although the management of emerging environmental risks has received more attention recently, planning and public policy scholars have not yet generated consensus on management approaches for environmental and occupational risks that remain poorly described, unquantified, and may be potentially 'unknowable'. Our case study focuses on exposure to respirable mineral dust (RMD), a specific category of particulate air pollution which includes examples such as respirable crystalline silica and asbestos fibres, as an example of a risk that is emerging and that has often 'escaped' regulations in many countries. This article (i) reviews prevailing risk management strategies and (ii) discusses their limitations when applied to the unique characteristics of RMD. The aim of the paper is to examine the suitability of existing risk management approaches for the evaluation of emerging environmental risks, which are bounded by significant uncertainties in quantifying the likelihood of the occurrence and/or severity of the hazard. We identify potential improvements to these strategies, highlighting the value of different protection levels, strategies, measures, and proactive actions which are enabled within an adaptive management framework that responds more nimbly to future changes.