George O. Rogers

Diffusion of emergency warning: Comparing empirical and simulation results

As officials consider emergency warning systems to alert the public to potential danger in areas surrounding hazardous facilities, the issue of warning system effectiveness is of critical importance. The purpose of this paper is to present the results of an analysis on the timing of warning system information dissemination including the alert of the public and delivery of a warning message. A general model of the diffusion of emergency warning is specified as a logistic function. Alternative warning systems are characterized in terms of the parameters of the model, which generally constrain the diffusion process to account for judged maximum penetration of each system for various locations and likelihood of the public’s being in those places by time of day. The results indicate that either telephone ring-down warning systems or tone-alert radio systems combined with sirens provide the most effective warning system under conditions of either very rapid onset, close proximity or both. These results indicate that single technology system provide adequate warning effectiveness when available warning time (after detection and the decision to warn) extends to as much as an hour. Moreover, telephone ring-down systems provide similar coverage at approximately 30 minutes of available public warning time.

Large-Scale Environmental Knowledge Investigating the Relationship Between Self-Reported and Objectively Measured Physical Environments

This article compares self-reported and objectively measured physical features in a large-scale environment. Environmental perception has been studied through object perception research but little is known about perception in full-scale environments. Also, few studies examine differences between self-reported and objective environments including the potential effects of distance and content. In this study, a questionnaire, satellite imagery, and geographic information system data were used. Results indicate that self-reported environments are different from objective environments. In addition, self-reported responses separate natural and built environments into two different dimensions. Water combines self-reported and objective measurements into a single dimension. Further analysis revealed that content (natural vs. built) and distance (300 ft vs. 1,500 ft) are important factors influencing the relationships between self-reported and objective environmental measurements. By better understanding relationships between self-reported and objective environments, landscape planners and designers can choose the most appropriate data type for analyzing specific planning and design decisions.

Landscape components, land use, and neighborhood satisfaction

Neighborhood satisfaction is an important component of life satisfaction. As a contributor to life satisfaction, neighborhood satisfaction is influenced by individual and household background variables. However, there is limited understanding of how physical environments influence neighborhood satisfaction. This paper examines the effect of landscape components (structures, pavement, trees) and land use (residential, commercial, and open space) on neighborhood satisfaction. A survey of 276 respondents in College Station, Texas, was georeferenced and analyzed with landscape components and land-use GIS data. A structural equation model (SEM) examines the relationships among background variables, land use, landscape components, and neighborhood satisfaction simultaneously. Landscape components and land use were both found to play an important role in neighborhood satisfaction. Trees were found to have a positive effect on neighborhood satisfaction while structures were negative. Pavement, when commercial land use and structures in the SEM model were accounted for, shows a positive relationship with neighborhood satisfaction, suggesting that not all pavement is seen as undesirable. Commercial land use was also found to have a negative effect on neighborhood satisfaction, while background variables have no significant impact. The amount and arrangement of land uses and landscape components in neighborhoods may improve the well-being of residents by increasing their neighborhood satisfaction.

Warning and response in two hazardous materials transportation accidents in the U.S.

Abstract Warning system effectiveness is critically important in selecting an appropriate emergency warning system to alert to public to potential danger. This

Siting potentially hazardous facilities: what factors impact perceived and acceptable risk?

Abstract This paper examines two explanations for the acceptance of technological facilities in a community. One explanation argues that facilities are accepted as a function of the benefits and inherent risks associated with the technology involved. The alternative explanation argues that facilities are accepted on the basis of the conditions of acceptability. Because the former posits that facilities are accepted as a function of the technology, policies based on this explanation attempt to redistribute the risks and benefits associated with technologies to achieve fairness. The latter suggests that the acceptance of facilities that pose risk to the community is as much a function of the conditions of acceptability as it is the type of technology involved. From this perspective policy should be sensitive to the process of siting, construction, operation and shutdown of the facility in the context of the comprehensive relationship between the technology and the community (i.e., in an ecological sense). Rather than focusing on the characteristics of the technology, this perspective focuses on the social institutional arrangements that make the technology acceptable. This paper examines six different technologies and eight separate conditions of acceptability in terms of public perception and acceptability of risk. The pattern of responses from a 1992 national survey of the United States reveal a stable pattern from technology to technology among the eight conditions of acceptability. The importance of the conditions examined in determining acceptability provides insight into the siting process by demonstrating an emphasis on sustainability through empowerment of self-determination.

Dynamic Risk Perception in Two Communities: Risk Events and Changes in Perceived Risk

This paper examines the relationship between perceived risk and hazard events in two communities in terms of the perception and acceptability of risk. One community experienced an acute risk event comprised of a fire at a chemical plant that resulted in a large-scale evacuation (an acute hazard). The other community was involved in a seven-year controversy over the siting of a hazardous waste incinerator (a chronic risk). While the results are broadly consistent with a learning model of perceived risk, the support is more limited than envisioned; hence, the static forces of risk perception are stronger than anticipated.

An approach for deriving emergency planning zones for chemical munitions emergencies

Abstract The selection of an emergency planning zone (EPZ) for hazardous materials is often a difficult technical as well as a political task. This paper descri

Residential Proximity, Perceived and Acceptable Risk

The perception of risk and the acceptance of it are partially a product of life experiences. This occurs because “ordinary-knowledge” is principally comprised of experiences, and the perception and acceptability of risk rests firmly upon that “data bank” of knowledge. Hence, life-experience is inherently related to perceived and acceptable risk. This paper focuses on the relationship between the life experiences associated with residential proximity, and the perception and acceptability of the risks associated with generating electricity in nuclear power plants. Perceived risk is operationally defined in t erms of estimated likelihood of occurrence, while acceptability of nuclear power is defined in terms of people’s favorable or unfavorable opinions regarding nuclear power plants. In the context of a simple social-structural model of perceived and acceptable risk, four potential explanations for enhanced acceptability among those residentially proximate with nuclear facilities are examined: 1) Residents, through the experience of living with hazard, are reinforced toward assigning lower probabilities to the potential risks associated with nuclear facilities. 2) The cognitive dissonance created by the acceptance of the risks associated with nuclear power is decreased by reducing perceived risk. 3) Nuclear neighbors are predisposed toward, educated about, and/or economically dependent upon nuclear power hence the more favorable attitudes toward it. 4) Nearby residents are systematically more altruistic — other oriented — than the general population and thus more willing to bear the risks associated with nuclear power. Low-probability/high-consequence risks are sometimes assessed in terms of revealed societal preferences. However, assessing risk in this manner without careful consideration of social processes involved is somewhat superficial and misleading. In this sense, a more complete understanding of the social processes involved in the perception and acceptability of risk is essential. The examination of these four hypotheses provides a foundation on which such an understanding may be established.

Local Preparedness for Chemical Accidents: A Survey of U.S. Communities

The preliminary results of a survey designed to assess the state of emergency preparedness in communities across the United States aid in the development of a conceptual approach to emergency management. The approach identifies the relationships among existing emergency-management systems and prac tices and assesses their effectiveness in alerting and notifying the public. A comparison of data gleaned from a survey of emergency-preparedness officials permits comparison of existing public-alert and notification systems with state- of-the-art technology, procedures, and management systems. The study also addresses the potential problems and constraints likely to thwart timely effec tive warning in the advent of an emergency. Finally, the authors make recom mendations for improving public-alert and notification systems in chemical emergencies.

The timing of emergency decisions: Modelling decisions by community officials during chemical accidents

Abstract Protecting the public from airborne chemical releases is limited by the timing of the implementation of actions taken and the capacity of those actions to avoid or reduce exposure. This paper examines the community decision processes during emergencies to identify critical factors asso- ciated with the timing of emergency warning, and protective action recommendations. This research examines the decision process by tracing emer- gency response from the outset of the community decision process, through the decision to warn the public, including the communication of hazard to the public, and the all-clear at the end of the emergency period. Both community authorities and the public cycle through hazard detection, assessment communication, and behavioral response as they become aware of the hazard. A sample of emergency decisions during chemical emergen- cies was examined via post-emergency interviews with key community officials. Emergency responders in a systematic sample of events after 1984, but prior to 1990, were interviewed in the Fall of 1989. Finding that decisions in more recent events were more easily reconstructed, a randomly selected half of the significant chemical emergencies occurring during 1990 were interviewed within weeks of the chemical events. Previous work [1] shows that community decision processes are seldom immediate and often involve information seeking. This descriptive work is expanded herein to provide better models of the key factors effecting decision processes in chemical emergencies. Regression models of these data indicate that protective action and warning decisions occur more rapidly than all-clear decisions, and that each decision is influenced by different factors in the decision process. Moreover, these data indicate that the role of experts changes throughout the emergency response. When decisions lead to the active avoidance of exposure, officials seem to take evasive action more quickly, but when failure to decide results in passive avoidance of exposure and continued in convenience of the public, the decision process is often protracted.