Indoor air quality in the 21st century: search for excellence

Field studies demonstrate that there are substantial numbers of dissatisfied people in many buildings, among them those suffering from sick building syndrome (SBS) symptoms, even though existing standards and guidelines are met. The reason is that the requirements specified in these standards are rather low, allowing a substantial group of people to become dissatisfied and to be adversely affected. A paradigm shift from rather mediocre to excellent indoor environments is foreseen in the 21st century. Based on existing information and on new research results, five principles are suggested as elements behind a new philosophy of excellence: 1) better indoor air quality increases productivity and decreases SBS symptoms; 2) unnecessary indoor pollution sources should be avoided; 3) the air should be served cool and dry to the occupants; 4) "personalized air", i.e. a small amount of clean air, should be served gently, close to the breathing zone of each individual; and 5) individual control of the thermal environment should be provided. These principles of excellence are compatible with energy efficiency and sustainability.     

Semi-volatile organic compounds in the Campaspe River system (Victoria, Australia)

The levels of semi-volatile organic compounds (SVOCs) in the Campaspe River system, North Central Victoria, Australia, were monitored from January to September 1995, and the environmental trends and sources of these compounds were determined. The land use within particular catchments dictated the complexity of the SVOCs in run-off water. Run-off from native forest contained the greatest number of SVOCs. Soil and ground litter were shown to contain the greatest complexity of SVOCs, mostly terpenes. However, only a small proportion were leached by run-off with the remainder being tightly bound to the soil or volatilizing to the atmosphere. Under the prevailing drought of early 1995, the rivers contained no detectable SVOCs until the first catchment run-off after significant rainfall in May. The maximum complexity and concentration of the SVOCs coincided with extensive run-off after heavy rainfall in June, effecting a surge of SVOCs with the flood peak. Fatty acids, their amides and hydrocarbons made up the majority of the compounds identified and were in the 1-39 micrograms/l concentration range. The levels then diminished as the catchment was flushed by continual run-off. These results support Lake's 1967 hypothesis that natural floodwaters contain a signature of SVOCs entering from the catchment. The downstream passage of these compounds was obstructed by a man-made storage, Lake Eppalock, with only low concentrations of SVOCs (1-3 micrograms/l) in the outflow, displaying no correlation to run-off.     

Mobilization of lead from human bone tissue during pregnancy and lactation--a summary of long-term research

The skeleton is potential endogenous source of lead during pregnancy and lactation. We have undertaken a longitudinal investigation into the mobilization of lead from the human maternal skeleton to determine whether lead is mobilized from the maternal skeleton during pregnancy and lactation, and if so, when and how much is released. Subjects in the study were migrants to Australia (n=15) whose skeletal lead isotopic composition (endogenous lead) was different to that prevailing in the Australian environment (exogenous lead). This migrant cohort was compared with 6 multi-generational Australian controls. Biological and environmental samples were taken pre-pregnancy where possible, throughout pregnancy and postpartum for at least 6 months. Newly-born infants of the migrant and Australian mothers were monitored for 6 months. Blood lead concentrations for the migrant mothers ranged from 1.5 to 20 microg/dl (geometric mean 2.8) and for Australian mothers ranged from 1.9 to 4.3 microg/dl (geometric mean 2.9). There was minimal change in lead isotopic composition of the Australian pregnant controls although there were increases of approximately 40% in blood lead concentration in 3 of 6 cases during the postpartum period and from 0 to 12% in the other 3. In the migrant pregnant subjects, the geometric mean skeletal lead contribution to blood lead using the isotopic composition was approximately 33% (range 10-88%) for 14 subjects using a revised estimate for exogenous lead. Skeletal contribution to blood lead during the postpartum period was significantly greater than during pregnancy (P<0.001). The skeletal contributions to blood lead are higher and the changes are more consistent in those subjects who conceived within 100 days of arrival in Australia compared with those who conceived longer than 100 days. In the migrant subjects, changes in blood lead concentration during pregnancy and postpartum varied from subject to subject with an overall 20% increase; the increases during the postpartum period were greater than during pregnancy (P<0.001). It was estimated that the amount of maternal skeletal lead mobilized during pregnancy and transferred to the infant via cord blood averaged approximately 79%. The increased skeletal contribution to blood lead is attributed to a low daily calcium intake of approximately 500 mgCa/day, a condition which was present in both migrant and Australian subjects. An ongoing clinical trial is providing a new cohort with calcium supplements. A summary of other aspects of the study is included and covers: additional flux released from the skeleton during pregnancy and postpartum; XRF bone lead results; urinary excretion of lead during pregnancy and postpartum; dietary contribution to blood lead in female adults and children; comparison of rates of exchange of lead in blood of newly-born infants and mothers; relationships of lead in breast milk to lead in blood, urine and diet of the infant and mother; changes in blood lead after cessation of breastfeeding; urinary lead isotopes during pregnancy and postpartum indicate no preferential partitioning of endogenous lead into plasma; a comparison of some aspects of the nonhuman primate and human pregnancy studies.     

Forecasting change using an interregional homogeneity index

This study of employment change in the Allentown-Bethlehem-Easton, SMSA applies an index of interregional homogeneity to determine the extent to which the industrial structure of the region over a nine-year period has been modifiedvis-a-vis that of the rest of the nation. Indices derived from the analysis are synthesized with a modified employment shift model to forecast expected employment for twenty-two industries in the ABE, SMSA for the year 1975. It is demonstrated that an interregional homogeneity index when combined with a shift and share model can be adapted to systematically forecast regional change. The concept employed is to first stratify the allocation of change to a sub-region in total and then to each industry.This study was made possible in part by a research grant from Waynesburg College.     

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.     

Full scale fire tests for ship accommodation quarters

Ten full-scale test fires were conducted in a chamber simulating a three person ship accommodation quarter. The test fires used three different ventilation conditions, two types of bunks and furnishings with either polyurethane foam or chloroprene foam. The chamber was instrumented to follow the development of the fire.The furnishings with polyurethane foam were readily ignited and produced an intense fire within 2 to 4 minutes. The furnishings with chloroprene foam ignited but burned slowly with a small flame or in smoldering combustion.The ventilation conditions had a significant effect on the development and intensity of the fire as the test fires were burning under oxygen-limiting conditions.The solid pan bunks retarded the early development of the fire compared to open bunks for polyurethane furnishings. However, once the mattresses on the three bunks were ignited the intensity of the test fires was similar for both types of bunks.     

Detection of enteric viruses, Giardia and Cryptosporidium in two different types of drinking water treatment facilities

In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity. Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants. Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size). Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR. Giardia and Cryptosporidium were detected by conventional staining methods and PCR. The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs. The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake. Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced. Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L. Virus count was reduced in sand of filters after washing. Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%). Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%). At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing. Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium. It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).     

Limit analysis of reinforced concrete cylindrical shell roofs

Two approximate yield criteria are proposed for reinforced concrete cylindrical shell element. Three lower bound solutions are developed for cylindrical shell roofs with free longitudinal edges. Two shells with different geometric parameters are analysed. Elastic analysis is also done at working load. Graphs are presented to show the variation of stress resultants at critical sections.     

THE EFFECTS OF IMPROVING SEWAGE SLUDGE DIGESTION

A model was developed and tested to investigate the effects of various parameters on the processing costs of anaerobic digestion. The model was based on empirical data collected from full-scale plants which varied in size from 35,000 to 900,000 population equivalents. (Equivalent to loading rates of 0.5 to 2.7 kg VS/m³/d.) In spite of different operating regimes and conditions of the plants analysed, various relationships were discovered between: sludge quality and volatile solids destruction; sludge quality and biogas yield; and, effluent volatile solids and dewatering. Where correlations existed, these were used to make predictions on operating costs of the digestion and dewatering plant based on sensitivity analysis. The results of the model were used to make recommendations on how to optimise the operation of an anaerobic digestion plant.