The short-term effects of air pollution on hospital admissions in four Australian cities

Background. This paper examines the short-term health effects of air pollution on daily hospital admissions in Australian cities (those considered comprise more than 50% of the Australian population) for the period 1996-99. Methods: The study used a similar protocol to overseas studies and derived single city and pooled estimates using different statistical approaches to assess the accuracy of the results. Results: There was little difference between the results derived from the different statistical approaches for cardiovascular admissions, while in those for respiratory admissions there were differences. For three of the four cities (for the other the results were positive but not significant), fine particles (measured by nephelometry - bsp) and nitrogen dioxide (NO2) have a significant impact on cardiovascular admissions (for total cardiac admissions, RR=1.0856 for a one-unit increase in bsp (10(-4). m(-1)), RR=1.0023 for a 1 ppb increase in NO2). For three of the four cities (for the other, the results were negative and significant), fine particles, NO2 and ozone have a significant impact on respiratory admissions (for total elderly respiratory admissions, RR=1.0552 per 1 unit (10(-4).m(-1)) increase in bsp, RR=1.0027 per 1ppb increase in NO2, RR=10014 per 1 ppb increase in ozone for elderly asthma and COPD admissions). In all analyses the particle and NO2 impacts appear to be related. Conclusions: Similar to overseas studies, air pollution has an impact on hospital admissions in Australian cities, but there can be significant differences between cities.

An analysis of relational complexity in an air traffic control conflict detection task

Theoretical analyses of air traffic complexity were carried out using the Method for the Analysis of Relational Complexity. Twenty-two air traffic controllers examined static air traffic displays and were required to detect and resolve conflicts. Objective measures of performance included conflict detection time and accuracy. Subjective perceptions of mental workload were assessed by a complexity-sorting task and subjective ratings of the difficulty of different aspects of the task. A metric quantifying the complexity of pair-wise relations among aircraft was able to account for a substantial portion of the variance in the perceived complexity and difficulty of conflict detection problems, as well as reaction time. Other variables that influenced performance included the mean minimum separation between aircraft pairs and the amount of time that aircraft spent in conflict.

Managing the airspace: A task analysis of Australian air traffic control

The aim of this study was to examine the way Australian air traffic controllers manage their airspace. Fourteen controllers ranging from 7 to 30 years experience were sampled from the Brisbane air traffic control centre. All had previously been endorsed for en route radar sectors. Five static pictures varying in workload level (low, medium and high) were presented to participants. Controllers were asked to work through the scenarios and describe aloud how they would resolve any potential conflicts between the aircraft. Following this controllers were asked a set of probe questions based on the critical decision method, to extract further information about the way they manage their airspace. A content analysis was used to assess patterns in the way controllers scan, strategies used in conflict detection and conflict resolution and the effect of workload on strategy choice. Findings revealed that controllers use specific strategies (such as working in a left to right scan or prioritising levels) when managing their airspace. Further analyses are still planned however a model based on the processes controllers used to resolve conflicts has been developed and will be presented as a summary of the results.

Ecological studies on river pollution control

This collection of papers records a series of studies, carried out over a period of some 50 years, on two aspects of river pollution control - the prevention of pollution by sewage biological filtration and the monitoring of river pollution by biological surveillance. The earlier studies were carried out to develop methods of controlling flies which bred in the filters and caused serious nuisance and possible public health hazard, when they dispersed to surrounding villages. Although the application of insecticides proved effective as an alleviate measure, because it resulted in only a temporary disturbance of the ecological balance, it was considered ecologically unsound as a long-term solution. Subsequent investigations showed that the fly populations in filters were largely determined by the amount of food available to the grazing larval stage in the form of filter film. It was also established that the winter deterioration in filter performance was due to the excessive accumulation of film. Subsequent investigations were therefore carried out to determine the factors responsible for the accumulation of film in different types of filter. Methods of filtration which were considered to control film accumulation by increasing the flushing action of the sewage, were found to control fungal film by creating nutrient limiting conditions. In some filters increasing the hydraulic flushing reduced the grazing fauna population in the surface layers and resulted in an increase in film. The results of these investigations were successfully applied in modifying filters and in the design of a Double Filtration process. These studies on biological filters lead to the conclusion that they should be designed and operated as ecological systems and not merely as hydraulic ones. Studies on the effects of sewage effluents on Birmingham streams confirmed the findings of earlier workers justifying their claim for using biological methods for detecting and assessing river pollution. Further ecological studies showed the sensitivity of benthic riffle communities to organic pollution. Using experimental channels and laboratory studies the different environmental conditions associated with organic pollution were investigated. The degree and duration of the oxygen depletion during the dark hours were found to be a critical factor. The relative tolerance of different taxa to other pollutants, such as ammonia, differed. Although colonisation samplers proved of value in sampling difficult sites, the invertebrate data generated were not suitable for processing as any of the commonly used biotic indexes. Several of the papers, which were written by request for presentation at conferences etc., presented the biological viewpoint on river pollution and water quality issues at the time and advocated the use of biological methods. The information and experiences gained in these investigations was used as the "domain expert" in the development of artificial intelligence systems for use in the biological surveillance of river water quality.

Monte Carlo Study of Particle Transport Problem in Air Pollution

2002 Mathematics Subject Classification: 65C05.

A Parameter Estimation and Identifiability Analysis Methodology Applied to a Street Canyon Air Pollution Model

Mathematical models are increasingly used in environmental science thus increasing the importance of uncertainty and sensitivity analyses. In the present study, an iterative parameter estimation and identifiability analysis methodology is applied to an atmospheric model – the Operational Street Pollution Model (OSPMr). To assess the predictive validity of the model, the data is split into an estimation and a prediction data set using two data splitting approaches and data preparation techniques (clustering and outlier detection) are analysed. The sensitivity analysis, being part of the identifiability analysis, showed that some model parameters were significantly more sensitive than others. The application of the determined optimal parameter values was shown to succesfully equilibrate the model biases among the individual streets and species. It was as well shown that the frequentist approach applied for the uncertainty calculations underestimated the parameter uncertainties. The model parameter uncertainty was qualitatively assessed to be significant, and reduction strategies were identified.

Audit report on the Iowa Water Pollution Control Works Financing Program and the Iowa Drinking Water Facilities Financing Program, joint programs of the Iowa Finance Authority and the Iowa Department of Natural Resources for the year ended June 30, 2015

Audit report on the Iowa Water Pollution Control Works Financing Program and the Iowa Drinking Water Facilities Financing Program, joint programs of the Iowa Finance Authority and the Iowa Department of Natural Resources for the year ended June 30, 2015