Jean-Christophe Vergnaud

Public-health impact of outdoor and traffic-related air pollution: a European assessment

BACKGROUND Air pollution contributes to mortality and morbidity. We estimated the impact of outdoor (total) and traffic-related air pollution on public health in Austria, France, and Switzerland. Attributable cases of morbidity and mortality were estimated. METHODS Epidemiology-based exposure-response functions for a 10 microg/m3 increase in particulate matter (PM10) were used to quantify the effects of air pollution. Cases attributable to air pollution were estimated for mortality (adults > or = 30 years), respiratory and cardiovascular hospital admissions (all ages), incidence of chronic bronchitis (adults > or = 25 years), bronchitis episodes in children (< 15 years), restricted activity days (adults > or = 20 years), and asthma attacks in adults and children. Population exposure (PM10) was modelled for each km2. The traffic-related fraction was estimated based on PM10 emission inventories. FINDINGS Air pollution caused 6% of total mortality or more than 40,000 attributable cases per year. About half of all mortality caused by air pollution was attributed to motorised traffic, accounting also for: more than 25,000 new cases of chronic bronchitis (adults); more than 290,000 episodes of bronchitis (children); more than 0.5 million asthma attacks; and more than 16 million person-days of restricted activities. INTERPRETATION This assessment estimates the public-health impacts of current patterns of air pollution. Although individual health risks of air pollution are relatively small, the public-health consequences are considerable. Traffic-related air pollution remains a key target for public-health action in Europe. Our results, which have also been used for economic valuation, should guide decisions on the assessment of environmental health-policy options.

Perspectives for integrating human and environmental risk assessment and synergies with socio-economic analysis

For more than a decade, the integration of human and environmental risk assessment (RA) has become an attractive vision. At the same time, existing European regulations of chemical substances such as REACH (EC Regulation No. 1907/2006), the Plant Protection Products Regulation (EC regulation 1107/2009) and Biocide Regulation (EC Regulation 528/2012) continue to ask for sector-specific RAs, each of which have their individual information requirements regarding exposure and hazard data, and also use different methodologies for the ultimate risk quantification. In response to this difference between the vision for integration and the current scientific and regulatory practice, the present paper outlines five medium-term opportunities for integrating human and environmental RA, followed by detailed discussions of the associated major components and their state of the art. Current hazard assessment approaches are analyzed in terms of data availability and quality, and covering non-test tools, the integrated testing strategy (ITS) approach, the adverse outcome pathway (AOP) concept, methods for assessing uncertainty, and the issue of explicitly treating mixture toxicity. With respect to exposure, opportunities for integrating exposure assessment are discussed, taking into account the uncertainty, standardization and validation of exposure modeling as well as the availability of exposure data. A further focus is on ways to complement RA by a socio-economic assessment (SEA) in order to better inform about risk management options. In this way, the present analysis, developed as part of the EU FP7 project HEROIC, may contribute to paving the way for integrating, where useful and possible, human and environmental RA in a manner suitable for its coupling with SEA.

Decisions with conflicting and imprecise information

When facing situations involving uncertainty, experts might provide imprecise and conflicting opinions. Recent experiments have shown that decision makers display aversion towards both disagreement among experts and imprecision of information. We provide an axiomatic foundation for a decision criterion that allows one to distinguish on a behavioral basis the decision maker’s attitude towards imprecision and disagreement. This criterion accommodates patterns of preferences observed in experiments that are precluded by two-steps procedures, where information is first aggregated, and then used by the decision maker. This might be seen as an argument for having experts transmitting a more detailed information to the decision maker.

Confidence measurement in the light of signal detection theory

We compare three alternative methods for eliciting retrospective confidence in the context of a simple perceptual task: the Simple Confidence Rating (a direct report on a numerical scale), the Quadratic Scoring Rule (a post-wagering procedure), and the Matching Probability (MP; a generalization of the no-loss gambling method). We systematically compare the results obtained with these three rules to the theoretical confidence levels that can be inferred from performance in the perceptual task using Signal Detection Theory (SDT). We find that the MP provides better results in that respect. We conclude that MP is particularly well suited for studies of confidence that use SDT as a theoretical framework.

A Positive Value of Information for a Non-Bayesian Decision-Maker

In the multi-prior framework, we consider that there exist two sorts of information process: revision information and focusing information. The second one is standard in economics while the former cannot be defined when there is only one prior. In this paper, we provide a coherent defmition of “revising” information structure. We show that we get a positive value of information. A partial order for those revision information structures is also proposed.

Metacognition about the past and future: quantifying common and distinct influences on prospective and retrospective judgments of self-performance

Abstract Metacognitive judgments of performance can be retrospective (such as confidence in past choices) or prospective (such as a prediction of success). Several lines of evidence indicate that these two aspects of metacognition are dissociable, suggesting they rely on distinct cues or cognitive resources. However, because prospective and retrospective judgments are often elicited and studied in separate experimental paradigms, their similarities and differences remain unclear. Here we characterize prospective and retrospective judgments of performance in the same perceptual discrimination task using repeated stimuli of constant difficulty. Using an incentive-compatible mechanism for eliciting subjective probabilities, subjects expressed their confidence in past choices together with their predictions of success in future choices. We found distinct influences on each judgment type: retrospective judgments were strongly influenced by the speed and accuracy of the immediately preceding decision, whereas prospective judgments were influenced by previous confidence over a longer time window. In contrast, global levels of confidence were correlated across judgments, indicative of a domain-general overconfidence that transcends temporal focus.

How to correctly assess mortality benefits in public policies

Abstract This paper concerns the difficulty of taking long-term effects on health into account in an economic valuation. Indeed, public decision makers should incorporate the cessation lag between implementation of an abatement policy and achievement of all of the expected mortality-related benefits for any projects involving health impacts. This paper shows how this time lag problem can be handled by proposing two approaches—either in terms of deaths avoided or of life years saved—within a dynamic perspective. The main findings are that long-term health benefits calculated by standard methods and widely applied to adverse health effects should be corrected downwards when incorporated into an economic analysis. The magnitude of correction depends on the discount rate, on technical choices dealing with epidemiology and on the method chosen to assess mortality benefits.

Information Externalities and Learning with Sequential Interactions

We develop a model of technological choice with social learning in which the timing of adoption of new technologies is endogenous. Social learning occurs through information externalities, because the decision of an early adopter reveals his private information to the other agent. In our model, not only the decision to adopt a new technology is informative for the agent who is in a waiting position, but also the decision to wait. We show that more informed agents act as “leaders” by adopting a new technology earlier than less informed agents. The latter act as “followers” by rationally imitating the adoption choices they observed previously. Although pure imitation is usually a source of inefficiency, in our context, imitation of early technological choices is socially efficient. This happens in our context because of complete revelation of useful information despite imitation. As a consequence there is a very low probability of making errors. We compare our context of social learning to other contexts, in which the revelation of useful information is incomplete and the probability of errors is larger. Although our context is informationally more efficient, the social surplus is not necessarily higher than in other contexts. Indeed, the process of information revelation can be highly time consuming, leading to large costs of delay, which may offset the information advantage.

Ambiguity reduction through new statistical data

Abstract We provide some objective foundations for a belief revision process in a situation where (i) the decision-makers initial probabilistic knowledge is imprecise and characterized by the core of a belief function, (ii) expected new data are themselves consistent with a belief function with known focal sets and (iii) the revision process is based on belief function combination. We study the properties of the information value for such a revising in the Gilboa–Schmeidler multi-prior model.

Choice axioms for a positive value of information

In this Chapter, we deal with the consistency of dynamic individual choices. We impose that a decision maker should value information as a consistency requirement and show that this is compatible with a relaxation of Hammond’s consequentialism. More precisely we show that an axiom that we dub “selection of optimal strategies” is enough to entail a positive value for information. This axiom does not imply the sure thing principle and therefore leaves room for alternatives to the expected utility model. We illustrate this through a decision theoretic model that is not based on probabilistic beliefs but possesses the property of positive value of information.