A methodology for estimating airborne virus exposures in indoor environments using the spatial distribution of expiratory aerosols and virus viability characteristics

This study investigated the feasibility of using the spatial distribution of expiratory aerosols and the viability functions of airborne viruses to estimate exposures to airborne viruses in an indoor environment under imperfectly mixed condition. A method adopting this approach was tested in an air-conditioned hospital ward. Artificial coughs were produced by aerosolizing a simulated respiratory fluid containing a known concentration of benign bacteriophage. The bacteriophage exposures estimated on the basis of the spatial aerosol distributions and its viability function were in reasonable agreement with those measured directly by biological air sampling and culturing. The ventilation flow and coughing orientation were found to play significant roles in aerosol transport, leading to different spatial distribution patterns in bacteriophage exposure. Bacteriophage exposures decreased with lateral distance from the infector when the infector coughed vertically upward. In contrast, exposures were constant or even increased with distance in the case of lateral coughing. The possibility of incorporating the proposed exposure estimation into a dose-response model for infection risk assessment was discussed. The study has also demonstrated the potential application of viability functions of airborne viral pathogens in exposure assessment and infection risk analysis, which are often unavailable in literature for some important communicable diseases. PRACTICAL IMPLICATIONS: The proposed method makes use of the viability function of the virus and the spatial distribution of the expiratory aerosols for virus exposure estimation. Spatial differences in aerosol distribution and its influences on virus exposure in an air space can be determined. Variations in infectious dose with carrier aerosol size could also be considered. The proposed method may serve as a tool for further investigation of ventilation design and infection control in clinical or other indoor environments.     

A FRAMEWORK FOR CLIMATE RISK MANAGEMENT APPLIED TO A UK WATER RESOURCE PROBLEM

Climate risk management is a new and evolving area and many decisions are likely to be affected by climate risks over the long-term. This paper presents a decision-making framework designed for managing climate alongside nonclimate risk factors. The framework describes a process that should help identify and manage these risks. It can be used to help decision-makers answer questions about whether adaptation is required, and, if so, which measures should be implemented. Adaptive management is recommended as a useful approach for dealing with climate and other uncertainties. This paper describes an application of the framework to a water resources case study. Feedback from training workshops based on four different case studies suggests the framework provides at minimum a useful (post-hoc) decision analysis tool. Potential users, who include planners, consultants and policy-makers have been largely positive about the prospective utility of the framework.     

工程项目动态集成化风险管理模式的探讨

在工程项目全寿命周期风险管理和集成化风险管理的基础上,提出了工程项目动态集成化风险管理模式,即在工程项目所处的风险系统中,纵向上考虑风险集合、风险管理组织、风险管理过程及风险管理目标沿工程项目全寿命周期的动态变化,横向上考虑风险集合、风险管理组织、风险管理过程及风险管理目标的集成化,将工程项目风险管理的动态性和集成化统一起来,为工程项目风险管理的研究工作提供理论依据.     

承包商施工合同风险分析及防范

在工程项目实施过程中,承包商会面临来自诸如工程本身、承包商自身、业主、外部环境变化和不可抗力事件的发生、合同条款以及合同类型等多方面的风险,这些风险因素将对承包商的经济效益产生重大影响.本文从规范合同用词、采取有效的报价策略、合同谈判、购买保险、利用保险、索赔管理等六个方面提出相应的防范措施,以期保护承包商的正当利益,更好地促进我国建筑市场健康稳定的发展.     

地铁的消防安全问题及其对策

通过实例分析了地铁潜在的火灾危险性，阐述了地铁火灾中人员疏散和灭火救援的艰难性，结合韩国地铁火灾教训，提出了加强我国地铁消防安全的对策和建议。     

Managing safety and hazard through dependability

There is an implied view, at the root of current techniques for dealing with structural safety, that safety factors or probabilities of failure exist objectively. An analogy between truth and safety is used in a critical analysis of the essential incompleteness of theoretical models. Theories are seen as social constructs which depend on the culture and objectives of those who build them. Theoretical models are dependable if they are highly tested. Dependability, it is argued, is a measure of truth content of a statement or of safety content of a structure. It is argued that it is necessary to move away from the idea that structural safety should be concerned with the prediction of a ‘true’ factor of safety, or probability of failure, to the idea of management of hazard as a process. It is argued that factors of safety and probabilities of failure are features of theoretical models to be used in the management of hazard. A hazard is a set of preconditions to failure. Hazard engineering should be concerned with hazard auditing and hazard management. A structure earns dependability through the process of hazard auditing based on critical tests of the design, construction and operation of the structure. Measures of dependability can be used in management of hazard. A conceptual model, which is an extension of the limit state hypervolume, is described and the requirements of a computer tool for the management of hazard outlined.     

ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN

A review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready-to-eat crops.     

Mercury contamination in fish from gold mining areas in Indonesia and human health risk assessment

This study investigates the effects on fish and assesses human health hazards from mercury released in two gold mining areas in Indonesia: Tatelu (North Sulawesi Province) and Galangan (Katingan District, Central Kalimatan Province). In Tatelu, 154 fish specimens of 10 freshwater species were collected, as well as five marine species from the fish market. The mean concentration of total mercury in muscles of freshwater fish from this area was 0.58+/-0.44 microg/g, with more than 45% of fish having Hg levels above the WHO guideline for human consumption of 0.5 microg/g. In Galangan, where 263 fish specimens of 25 species were collected, the total mercury in muscles averaged 0.25+/-0.69 microg/g. Excluding data from flooded open pits in sub-area P4, mean Hg levels in fish from Galangan were 2 to 4 times lower than 0.5 microg/g, while fewer than 10% of fish from Galangan exceeded WHO guidelines. The Hazard Quotient (HQ) was applied to both areas to determine the threat of MeHg exposure for communities in both areas. The HQ is a risk assessment indicator which defines the ratio of exposure level to a single substance in relation to a reference dose. Samples from Tatelu (excluding marine species) had an HQ above one, while those from Galangan resulted in values of 2.4 for the whole area and 9.9 for sub-area P4, pointing to potentially harmful fish consumption for the local population. By using the single-compartment model to estimate mercury levels in blood and hair from daily intake dose, sub-area P4 showed the highest levels, higher than the upper limit guideline for pregnant women, but still lower than threshold levels associated with observed clinical effects.     

Waterborne rotavirus: A risk assessment

A risk assessment approach was used to estimate the public health impacts from exposure to human rotavirus in drinking and recreational waters. Rotavirus is the major cause of viral gastroenteritis worldwide and several waterborne outbreaks have been documented. This results in a significant economic impact on society in terms of direct medical costs, loss of work, quality of life and mortality. The virus is common in domestic wastewater and polluted surface waters. Dose-response data in human adult volunteers indicate that it is the most infective of all the enteric viruses, and this was used to develop a microbial risk assessment model to estimate daily and yearly risks of infection, morbidity and mortality for exposure via drinking and recreational waters using existing information on the occurrence of rotavirus. The disease is most severe for the very young, the elderly, and the immunocompromised. Case fatality rates in the United States are 0.01% in the general population, 1% in the elderly, and up to 50% in the immunocompromised. Analysis indicates that significant risks of disease (5 × 10⁻¹−2.45 × 10⁻³) could result for drinking and recreational waters in which rotavirus has been detected. The major limitation in assessing the risks of waterborne rotaviral infections at present is the lack of data on its occurrence in water and the potential for human exposure.     

住房抵押贷款的理性违约及其风险的规避

分析了住房抵押贷款中借款人的理性违约，认为因住房贬值而导致的借款人理性违约，实质上是住房的价格风险在供款人和贷款人之间的重新再分配。基于对我国住房抵押贷款市场中缺乏违约风险规避机制的分析，作者提出了建立我国由政府性质的担保机构和商业保险公司共同提供保险的综合违约风险规避机制的设想。此外，就建立政府性质担保机构的问题进行了着重探讨，通过对美国联邦住房管理局（FHA）的住房抵押贷款互助保险基金（MMIF）的分析，并结合中国实际，得出了中国有必要设立政府性质担保机构的结论。