The field performance of frontal air bags: a review of the literature

This article presents a broad review of the literature on frontal air bag field performance, starting with the initial government and industry projections of effectiveness and concluding with the most recent assessments of depowered systems. This review includes as many relevant metrics as practicable, interprets the findings, and provides references so the interested reader can further evaluate the limitations, confounders, and utility of each metric. The evaluations presented here range from the very specific (individual case studies) to the general (statistical analyses of large databases). The metrics used to evaluate air bag performance include fatality reduction or increase; serious, moderate, and minor injury reduction or increase; harm reduction or increase; and cost analyses, including insurance costs and the cost of life years saved for various air bag systems and design philosophies. The review begins with the benefits of air bags. Fatality and injury reductions attributable to the air bag are presented. Next, the negative consequences of air bag deployment are described. Injuries to adults and children and the current trends in air bag injury rates are discussed, as are the few documented instances of inadvertent deployments or non-deployment in severe crashes. In the third section, an attempt is made to quantify the influence of the many confounding factors that affect air bag performance. The negative and positive characteristics of air bags are then put into perspective within the context of societal costs and benefits. Finally, some special topics, including risk homeostasis and the performance of face bags, are discussed.     

A review of emerging technologies for remediation of PFASs

The need for remediation of poly‐ and perfluoroalkyl substances (PFASs) is growing as a result of more regulatory attention to this new class of contaminants with diminishing water quality standards being promulgated, commonly in the parts per trillion range. PFASs comprise >3,000 individual compounds, but the focus of analyses and regulations has generally been PFASs termed perfluoroalkyl acids (PFAAs), which are all extremely persistent, can be highly mobile, and are increasingly being reported to bioaccumulate, with understanding of their toxicology evolving. However, there are thousands of polyfluorinated “PFAA precursors”, which can transform in the environment and in higher organisms to create PFAAs as persistent daughter products. Some PFASs can travel miles from their point of release, as they are mobile and persistent, potentially creating large plumes. The use of a conceptual site model (CSM) to define risks posed by specific PFASs to potential receptors is considered essential. Granular activated carbon (GAC) is commonly used as part of interim remedial measures to treat PFASs present in water. Many alternative treatment technologies are being adapted for PFASs or ingenious solutions developed. The diversity of PFASs commonly associated with use of multiple PFASs in commercial products is not commonly assessed. Remedial technologies, which are adsorptive or destructive, are considered for both soils and waters with challenges to their commercial application outlined. Biological approaches to treat PFASs report biotransformation which creates persistent PFAAs, no PFASs can biodegrade. Water treatment technologies applied ex situ could be used in a treatment train approach, for example, to concentrate PFASs and then destroy them on‐site. Dynamic groundwater recirculation can greatly enhance contaminant mass removal via groundwater pumping. This review of technologies for remediation of PFASs describes that:

• GAC may be effective for removal of long‐chain PFAAs, but does not perform well on short‐chain PFAAs and its use for removal of precursors is reported to be less effective;
• Anion‐exchange resins can remove a wider array of long‐ and short‐chain PFAAs, but struggle to treat the shortest chain PFAAs and removal of most PFAA precursors has not been evaluated;
• Ozofractionation has been applied for PFASs at full scale and shown to be effective for removal of total PFASs;
• Chemical oxidation has been demonstrated to be potentially applicable for some PFAAs, but when applied in situ there is concern over the formation of shorter chain PFAAs and ongoing rebound from sorbed precursors;
• Electrochemical oxidation is evolving as a destructive technology for many PFASs, but can create undesirable by‐products such as perchlorate and bromate;
• Sonolysis has been demonstrated as a potential destructive technology in the laboratory but there are significant challenges when considering scale up;
• Soils stabilization approaches are evolving and have been used at full scale but performance need to be assessed using appropriate testing regimes;
• Thermal technologies to treat PFAS‐impacted soils show promise but elevated temperatures (potentially >500 °C) may be required for treatment.

There are a plethora of technologies evolving to manage PFASs but development is in its early stage, so there are opportunities for much ingenuity.     

An Ecoregional Approach to the Economic Valuation of Land- and Water-Based Recreation in the United States

/ This paper describes a framework for estimating the economic value of outdoor recreation across different ecoregions. Ten ecoregions in the continental United States were defined based on similarly functioning ecosystem characters. The individual travel cost method was employed to estimate recreation demand functions for activities such as motor boating and waterskiing, developed and primitive camping, coldwater fishing, sightseeing and pleasure driving, and big game hunting for each ecoregion. While our ecoregional approach differs conceptually from previous work, our results appear consistent with the previous travel cost method valuation studies.KEY WORDS: Recreation; Ecoregion; Travel cost method; Truncated Poisson model     

Complex social structure of southern flying squirrels is related to spatial proximity but not kinship

Social individuals have organized relationships that affect fitness and so a species' tendency to be social has important implications for its population ecology, gene flow, and its distribution in space and time. We quantitatively examined the social structure of southern flying squirrels (Glaucomys volans) and tested for a role of kinship and prior familiarity in predicting social structure. To quantify social structure, we monitored nest group composition of southern flying squirrels. All squirrels at the study site were marked with passive integrated transponder (PIT) tags and nest cavity entrances were monitored with automated PIT tag recorders for a period of 28 months. Squirrels were genotyped at eight microsatellite loci. Permutation tests of associations suggested that individuals nested with other specific individuals more often than expected by chance. The lagged association rate indicated that relationships were stable and persisted across seasons and years. Multiple summer nest associates came together in winter to form larger nest groups which were likely important for social thermoregulation. A measure of prior familiarity, but not kinship, was related to the proportion of time individuals nested together during winter. We suggest that the evolution of sociality in southern flying squirrels is driven largely by mutually beneficial behaviors related to social thermoregulation although other, as of yet, unidentified mechanisms are needed to explain sociality in the warm season. We hypothesize that minimum group size requirements associated with social thermoregulation could explain the absence of this species in patchy landscapes and aspects of range boundary dynamics near their northern range boundary.