Differences in views of experts about their role in particulate matter policy advice: Empirical evidence from an international expert consultation

There is ample scientific evidence of adverse health effects of air pollution at exposure levels that are common among the general population. Some points of uncertainty remain, however. Several theories exist regarding the various roles that experts may play when they offer policy advice on uncertain issues such as particulate matter (PM). Roles may vary according to e.g. the views of the expert on the science policy interface or the extent to which she/he involves stakeholders. Empirical underpinning of these theories, however, does not exist. We therefore conducted a consultation with experts on the following research question: What are PM experts' views on their roles when providing policy advice? Q methodology was used to empirically test theoretical notions concerning the existence of differences in views on expert roles. Experts were selected based on a structured nominee process. In total, 31 international PM experts participated. Responses were examined via Principal Component Analysis, and for the open-ended questions, we used Atlas.ti software. Four different expert roles were identified among the participating experts. Main differences were found with respect to views on the need for precautionary measures and on the experts positioning within the science-policy interface. There was consensus on certain issues such as the need for transparency, general disagreement with current policies and general agreement on key scientific issues. This empirical study shows that while most PM experts consider their views on the risks of PM to be in line with those of their colleagues, four distinct expert roles were observed. This provides support for thus far largely theoretical debates on the existence of different roles of experts when they provide policy advice. (C) 2016 The Authors. Published by Elsevier Ltd.