How valid are parents' questionnaire responses regarding building characteristics, mouldy odour, and signs of moisture problems in Swedish homes?

Aim: Questionnaires are a cheap means of studying large populations but the information obtained from them is seldom validated. Earlier studies have reported both high and low levels of agreements between inspectors' observations and occupants' reports regarding home environmental factors that included moisture problems. The aim of this study was to validate information received from a questionnaire survey regarding building characteristics, mouldy odour, and signs of moisture problems in 390 Swedish homes.

Analysis of archaeal core ether lipids using Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS): Exploring a new prospect for the study of biomarkers in geobiology.

The capability of Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) of analysing molecular archaeal biomarkers in geobiological samples was tested and demonstrated. Using a bismuth cluster primary ion source, isopranyl glycerol di- and tetraether core lipids were detected in small amounts of total organic extracts from methanotrophic microbial mats, simultaneously and without further chemical treatment and chromatographic separation. ToF-SIMS was also employed to track the distribution of fossilized ether lipids in a massive carbonate (aragonite) microbialite that precipitated as a result of the microbial anaerobic oxidation of methane.

Day-care attendance and increased risk for respiratory and allergic symptoms in preschool age.

Background: The reported impact of day-care attendance on respiratory and atopic symptoms has varied between studies from different countries. Regarding to the 'hygiene-hypothesis', day-care attendance may lead to less sensitization later in life, but the question still is whether day-care attendance and subsequent exposure to more frequent early infections is a risk or a protection against future allergic disease or asthma (atopic and nonatopic).

Methods: A cross-sectional postal questionnaire was replied by parents of 10,851 children, aged 1-6 years, in the year 2000 in a Swedish region (DBH-phase 1).

Phthalates in indoor dust and their association with building characteristics.

In a recent study of 198 Swedish children with persistent allergic symptoms and 202 controls without such symptoms, we reported associations between the symptoms and the concentrations of n-butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) in dust taken from the childrens' bedrooms. In the present study we examined associations between the concentrations of different phthalate esters in the dust from these bedrooms and various characteristics of the home. The study focused on BBzP and DEHP because these were the phthalates associated with health complaints.

Association between ventilation rates in 390 Swedish homes and allergic symptoms in children.

Unlabelled: The aim of the study was to test the hypothesis that a low-ventilation rate in homes is associated with an increased prevalence of asthma and allergic symptoms among children. A total of 198 cases (with at least two of three symptoms: wheezing, rhinitis, eczema) and 202 healthy controls, living in 390 homes, were examined by physicians. Ventilation rates were measured by a passive tracer gas method, and inspections were carried out in the homes.

Emissions from an automobile fire.

The emissions from automobile fires have been investigated. The main gas phase components were analysed in small-scale tests with representative material from an automobile. A more detailed investigation of full-scale simulated automobile fires was also conducted, including the characterisation of gas phase components, particulates and run-off water from extinguishing activities.

Spectral line narrowing of a photonically generated microwave frequency comb with vertical-cavity surface-emitting laser mode-locked coupled oscillators.

A technique is presented for narrowing the spectral linewidth of microwave signals generated photonically by heterodyning a pair of vertical-cavity surface-emitting lasers forming an extended optically coupled cavity. The experimentally demonstrated linewidth reduction, by as much as a factor of 10(4)--to less than 10 kHz in microwave frequencies up to a couple of gigahertz--is approximately ten times that expected with conventional line-narrowing techniques such as optical feedback. An interpretation is given in terms of mode locking in pairs of optically coupled lasers as a first demonstration in the frequency domain of lag synchronization of coupled oscillators.

The association between asthma and allergic symptoms in children and phthalates in house dust: a nested case-control study.

Global phthalate ester production has increased from very low levels at the end of World War II to approximately 3.5 million metric tons/year. The aim of the present study was to investigate potential associations between persistent allergic symptoms in children, which have increased markedly in developed countries over the past three decades, and the concentration of phthalates in dust collected from their homes.

Dampness in buildings and health (DBH): Report from an ongoing epidemiological investigation on the association between indoor environmental factors and health effects among children in Sweden.

Unlabelled: With the aim of identifying health-relevant exposures in buildings, an epidemiological study "Dampness in Buildings and Health" (DBH) started in the year 2000 in Sweden. The health focus of the study is on asthma and allergic symptoms among small children and their parents. The first step in the study was an epidemiological cross-sectional questionnaire on housing and health involving 14,077 preschool children in the county of Värmland in Sweden (March-April 2000).

Mass spectrometric imaging of lipids in brain tissue.

The spatial distributions of various specific lipids in freeze-dried mouse brain sections were monitored using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Mouse brain sections were prepared by cryosectioning, rinsing in 0.15 M NH3HCOO, and freeze-drying, after which the samples were analyzed directly by TOF-SIMS, using Au3+ ions as primary ions.

Dampness in buildings as a risk factor for health effects, EUROEXPO: a multidisciplinary review of the literature (1998-2000) on dampness and mite exposure in buildings and health effects.

Unlabelled: The scientific literature on health effects from dampness in buildings, including mite exposure over the period 1998-2000 has been reviewed by an European group (EUROEXPO) of eight scientists in experience from medicine, epidemiology, toxicology and engineering. Forty studies deemed relevant have been the foundation for the conclusions. Dampness in buildings is a risk factor for health effects among atopics and non-atopics both in domestic and in public environments.

Surface chemical analysis of carbohydrate materials used for chromatography media by time-of-flight secondary ion mass spectrometry.

The surface chemical structure of two raw materials (agarose and dextran) and four base matrixes used in the manufacture of chromatography media were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results show that the small differences in molecular structure between these materials result in significant differences in the TOF-SIMS spectra and that these differences can be identified and quantified using either of two different approaches. In a novel approach, fragment ion distributions were extracted from the TOF-SIMS spectra for each material, providing an immediate and systematic overview of the spectral features.

Imaging of membrane lipids in single cells by imprint-imaging time-of-flight secondary ion mass spectrometry.

A new method for identification and localization of organic molecules in biological samples is described. The method involves making an imprint of a biological sample on a silver (Ag) surface and subsequent analysis of the imprint by imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS). Using this method, detection of unfragmented, Ag cationized molecules at a spatial resolution of <0.

Pet-keeping in early childhood and airway, nose and skin symptoms later in life.

Background: It is discussed whether exposure to pets during childhood is a risk or a protective factor for sensitization and allergic symptoms. The aim of this study was to investigate the association between pet-keeping at time of birth and allergic symptoms in airways, nose and skin among young children in Sweden.

Method: A questionnaire was sent to the parents of 14 077 children (1-6 years), the focus being on allergic symptoms, home environment and other background factors including pet-keeping and avoidance behaviour.

Characterization of an Ellipsoidal Radiometer.

An ellipsoidal radiometer has been characterized using a 25 mm variable-temperature blackbody as a radiant source. This radiometer is intended for separating radiation from convection effects in fire test methods. The characterization included angular response, responsivity, and purge-gas flow effect studies.

Tribological investigation of oriented HDPE.

The possibility to control the wear properties of high-density polyethylene (HDPE) material at an early processing stage is explored. Wear measurements of cold roll-drawn HDPE with two different draw ratios were carried out for three sliding planes, each in two directions. The dependence of the wear properties on the degree and direction of orientation was investigated.

Fire-LCA study of TV sets with V0 and HB enclosure material.

A novel Life-Cycle Assessment model (Fire-LCA) has been defined for the determination of the environmental impact of measures taken to attain a high level of fire safety. This study, which represents the first application of this LCA model, concentrates on a comparison between a TV with an enclosure manufactured with a flame retardant (FR) plastic (V0-rated high impact polystyrene, HIPS, typical for the US market) and one manufactured with a non-flame retardant (HB-rated HIPS, typical for the European market). A fire model has been defined based on international statistics, which indicate that use of V0 rated enclosure material essentially removes the risk of TV fires while approximately 165 TV fires occur per million TVs in Europe each year where the enclosure material is breached.

Determinations of PCB within a project to develop cleanup methods for PCB-containing elastic sealant used in outdoor joints between concrete blocks in buildings.

Determinations of PCB were carried out as part of a project aimed at developing cleanup methods for PCB-containing elastic sealant used in outdoor joints between concrete blocks. The goals of the project were to develop methods, which minimise the spread of PCB to the outdoor environment and to indoor air, and which keep the PCB levels as low as reasonably possible in the workplace environment whilst removing the elastic sealant. The following PCB determinations were carried out: (1) concentration in the elastic sealant; (2) concentration in the concrete close to the sealant; (3) concentration in soil; (4) concentration in the indoor air; and (5) concentration in the air in the workplace environment.

Materials emission of chemicals--PVC flooring materials.

Data of chemical emissions from flooring materials have been collected and investigated in a database known as METS. The emission tests are performed using the Field and Laboratory Emission Cell (FLEC). The emission rates of total volatile organic compounds (TVOC) in the boiling point range of hexane to octadecane varies from around 4,000 micrograms/(m2.