The Historical Development of Public Health Responses to Disasters

The first of a series of state-of-the-art reviews commissioned to mark Disasters' 21st anniversary, this paper considers key publications on public health aspects of natural disasters, refugee emergencies and complex humanitarian disasters over the past twenty-odd years. The literature is reviewed and important signposts highlighted showing how the field has developed. This expanding body of epidemiological research has provided a basis for increasingly effective prevention and intervention strategies.     

Receptor modeling application framework for particle source apportionment

Receptor models infer contributions from particulate matter (PM) source types using multivariate measurements of particle chemical and physical properties. Receptor models complement source models that estimate concentrations from emissions inventories and transport meteorology. Enrichment factor, chemical mass balance, multiple linear regression, eigenvector. edge detection, neural network, aerosol evolution, and aerosol equilibrium models have all been used to solve particulate air quality problems, and more than 500 citations of their theory and application document these uses. While elements, ions, and carbons were often used to apportion TSP, PM10, and PM2.5 among many source types, many of these components have been reduced in source emissions such that more complex measurements of carbon fractions, specific organic compounds, single particle characteristics, and isotopic abundances now need to be measured in source and receptor samples. Compliance monitoring networks are not usually designed to obtain data for the observables, locations, and time periods that allow receptor models to be applied. Measurements from existing networks can be used to form conceptual models that allow the needed monitoring network to be optimized. The framework for using receptor models to solve air quality problems consists of: (1) formulating a conceptual model; (2) identifying potential sources; (3) characterizing source emissions; (4) obtaining and analyzing ambient PM samples for major components and source markers; (5) confirming source types with multivariate receptor models; (6) quantifying source contributions with the chemical mass balance; (7) estimating profile changes and the limiting precursor gases for secondary aerosols; and (8) reconciling receptor modeling results with source models, emissions inventories, and receptor data analyses.     

Exposure of trucking company workers to particulate matter during the winter

This study analyzed the workplace area concentrations and the personal exposure concentrations to fine particulate (PM_2.5), elemental carbon (EC), and organic carbon (OC) measured during the winter period in trucking companies. The averaged personal exposure concentrations at breathing zones of workers are much greater than those of the microenvironment concentrations. The highest difference between the area (microenvironment) and personal exposure concentrations was in the PM_2.5 concentrations followed by the OC concentrations. The area concentrations of PM_2.5, EC, and OC at a large terminal were higher than those at a small one. The highest area concentrations of PM_2.5, EC, and OC were observed in the shop areas followed by pick-up and delivery (P&D) areas. The area concentrations and personal exposure to PM_2.5, EC, and OC in the shop and P&D areas which are highly affected by diesel engine exhaust emissions were much higher than those in the docks which are significantly affected by liquefied petroleum gas (LPG) engine exhaust emissions. The highest EC fraction to the total carbon (EC + OC) concentrations was observed in the shops, while the lowest one was identified in the offices. The personal exposure of the smoking workers to PM_2.5 and OC was much higher than that of the non-smoking workers. However, the smoking might not significantly contribute to the personal exposure to EC. There were significant correlations between the PM_2.5 and OC concentrations in both the area and personal exposure concentrations. However, significant correlations between the PM_2.5 and EC concentrations and between the OC and EC concentrations were not identified.     

Sorption of cobalt and nickel on anaerobic granular sludges: isotherms and sequential extraction

The objective of this study was to investigate the sorption capacity and the fractionation of sorbed nickel and cobalt onto anaerobic granular sludges. Two different anaerobic granular sludges (non-fed, pH=7) were loaded with nickel and cobalt in adsorption experiments (monometal and competitive conditions). The combination of sequential extraction with the sorption isotherm analysis allowed the assessment of the sorption capacity of individual fractions present in the anaerobic granular sludges. The operational fractionation of the sorbed heavy metals was determined using a modified Tessier sequential extraction procedure. The sorption characteristics of each extracted fraction (exchangeable, carbonates, organic matter/sulfides and residual fractions) fitted well to the Langmuir model. The organic matter/sulfides fraction showed the highest affinity for cobalt and nickel in both sludges investigated compared to the other operationally defined fractions. The presence of iron negatively affected cobalt and nickel accumulation in this organic matter/sulfides fraction. The trace metals-iron sulfide interactions are likely to be the key process in controlling the distribution of cobalt and nickel during sorption onto non-fed methanogenic granules due to the high affinity of iron sulfides towards the metals studied.     

Mercury baseline levels in Flemish soils (Belgium)

It is important to establish contaminant levels that are normally present in soils to provide baseline data for pollution studies. Mercury is a toxic element of concern. This study was aimed at assessing baseline mercury levels in soils in Flanders. In a previous study, mercury contents in soils in Oost-Vlaanderen were found to be significantly above levels reported elsewhere. For the current study, observations were extended over two more provinces, West-Vlaanderen and Antwerpen. Ranges of soil Hg contents were distinctly higher in the province Oost-Vlaanderen (interquartile range from 0.09 to 0.43 mg/kg) than in the other provinces (interquartile ranges from 0.7 to 0.13 and 0.7 to 0.15 mg/kg for West-Vlaanderen and Antwerpen, respectively). The standard threshold method was applied to separate soils containing baseline levels of Hg from the data. Baseline concentrations for Hg were characterised by a median of 0.10mg Hg/kg dry soil, an interquartile range from 0.07 to 0.14 mg/kg and a 90% percentile value of 0.30 mg/kg. The influence of soil properties such as clay and organic carbon contents, and pH on baseline Hg concentrations was not important. Maps of the spatial distribution of Hg levels showed that the province Oost-Vlaanderen exhibited zones with systematically higher Hg soil contents. This may be related to the former presence of many small-scale industries employing mercury in that region.     

Development of a sampling train for arsenic in pyrolysis vapours resulting from pyrolysis of arsenic containing wood waste

In the present study a sampling and analysis method for arsenic emissions during pyrolysis of arsenic containing wood, such as chromated copper arsenate (CCA) treated wood, has been developed. The procedure is based on the NIOSH (National Institute for Occupational Safety and Health) standard for arsenic trioxide sampling. Validation for this specific application is needed since pyrolysis of arsenic containing wood leads to a gas stream containing sticky tar compounds and aerosols. Validation was carried out through tube furnace experiments using both CCA treated wood and arsenic trioxide powder as input. The outlet of the tube furnace was coupled to a cooling section and sampling train. The sampling train consisted of one or more filter sections and impingers. Different combinations of filters (untreated or impregnated) and impingers, as well as different combinations of washing solutions were tested. The different units of the sampling train were analysed by inductively coupled plasma mass spectrometry (ICP-MS) in order to determine the distribution of arsenic over the different units. For the working conditions considered (pyrolysis at 350 degrees C for 20 minutes with a nitrogen flow rate of 100 Nl h(-1)) the combination of a quartz cooling tube and a cellulose ester membrane filter impregnated with a Na2CO3-glycerol solution was sufficient to capture the arsenic. Two extra impingers (the first one containing 50 ml HNO3 1 M in the case of CCA treated wood and 50 ml NaOH 0.1 M in the case of As2O3 and the second one containing 50 ml NaOH 0.1 M) were added downstream of the filter section as backup either in case of filter failure or to check whether all the arsenic released is captured by the cooling tube and filter.     

Impacts of ocean CO2 disposal on marine life: II. Probabilistic plume exposure model used with a time‐varying dose‐response analysis

A method to evaluate aquatic mortality given a pollutant distribution is presented and applied to several sample low pH plumes representing various ocean CO₂ disposal schemes. The method is an improvement over current analysis because it integrates the mortality due to timevarying exposure to low pH with the probabilistic experiences of passive organisms subject to turbulent lateral diffusion as they pass through the plume. For the examples presented, the plume was discretized laterally into lanes and longitudinally by time steps, and a random walk model accounting for the scaledependent nature of relative diffusion was used to simulate the organism pathways over one time step. From these simulations, the probability that an organism will be in a given lane, , one time step after it starts from an initial lane, , was determined for all combinations of and . These probabilities were used to find the number of organisms following each of the possible pathways, and the mortality to the organisms due to their time varying exposure to low pH was determined by using the toxicity model described in part I of this paper. The integrated method allows the impact of the plume to be described in terms of total organism mortality as well as spatial deficit of organisms.     

Statistical determination of the optimal sample size of secondary effluent BOD5 and SS

A statistical technique is presented for determining the optimal sample size required to estimate the true geometric mean with an allowable error at a desired level of confidence. Attention is focused on its application in the monitoring of secondary effluent BOD₅ and SS. It is concluded that continuous monitoring of effluent BOD₅ or SS throughout the year may generate much more data than are required for practical purposes. This statistical method may be used by operators or regulatory agencies to formulate cost-effective monitoring schemes. Records of the sample size data of secondary effluent BOD₅ and SS across Canada are also discussed.     

Impacts of ocean CO2 disposal on marine life: I. A toxicological assessment integrating constant‐concentration laboratory assay data with variable‐concentration field exposure

Feasibility studies suggest that the concept of capturing CO₂ from fossil fuel power plants and discharging it to the deep ocean could help reduce atmospheric CO₂ concentrations. However, the local reduction in seawater pH near the point of injection is a potential environmental impact. Data from the literature reporting on toxicity of reduced pH to marine organisms potentially affected by such a plume were combined into a model expressing mortality as a function of pH and exposure time. Since organisms exposed to real plumes would experience a time‐varying pH, methods to account for a variable exposure were reviewed and a new method developed based on the concept of isomortality. In part II of this paper, the method is combined with a random‐walk model describing the transport of passive organisms through a low pH plume leading to a Monte‐Carlo‐like risk assessment which is applied to several candidate CO₂ injection scenarios.     

Evolution of the magnitude and spatial extent of the weekend ozone effect in California's South Coast Air Basin, 1981-2000

Since the mid-1970s, ozone (O3) levels in portions of California's South Coast Air Basin (SoCAB) on weekends have been as high as or higher than levels on weekdays, even though emissions of O3 precursors are lower on weekends. Analysis of the ambient data indicates that the intensity and spatial extent of the weekend O3 effect are correlated with-day-of-week variations in the extent of O3 inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO2), and rates of O3 accumulation. Lower NO mixing ratios and higher NO2/oxides of nitrogen (NOx) ratios on weekend mornings allow O3 to begin accumulating approximately an hour earlier on weekends. The weekday/weekend differences in the duration of O3 accumulation remained relatively constant from 1981 to 2000. In contrast, the rate of O3 accumulation decreased by one-third to one-half over the same period; the largest reductions occurred in the central basin on weekdays. Trends in mixing ratios of O3 precursors show a transition to lower volatile organic compound (VOC)/NOx ratios caused by greater reductions in VOC emissions. Reductions in VOC/NOx ratios were greater on weekdays, resulting in higher VOC/NOx ratios on weekends relative to weekdays. Trends in VOC/NOx ratios parallel the downward trend in peak O3 levels, a shift in the location of peak O3 from the central to the eastern portion of the basin, and an increase in the magnitude and spatial extent of the weekend O3 effect.