Indoor and Built Environment

The objective of this study was to develop energy efficient ventilation strategies that will provide both a healthy and comfortable indoor climate and reduce energy consumption compared to present ventilation standards. Humidity was used as a control parameter for the ventilation. Four different ventilation strategies were tested in a test apartment. The results of the experiments indicated that humidity can be used as a control parameter for ventilation and that energy can be saved without compromising indoor air quality.

Dampness in buildings is a common reason for a variety of health-related symptoms in the inhabitants. An obvious solution to at least part of this problem would be to take measures in order to keep a building dry in those parts of it that have not been intended to handle water. This article describes a Swedish building research project where more than 4000 apartments were built in Sweden according to a water damage quality control scheme. This has resulted in a total absence of water damage during a twelve-year period.

A cross-sectional study was carried out to investigate the occurrence of respiratory and other symptoms among workers in 25 buildings in Mauritius. Buildings were randomly selected and a self-administered questionnaire was distributed to the office occupants to investigate personal characteristics, work environment and demographic factors. Other questions related to the indoor climate at work included: perception of any health symptoms, psychosocial and physical conditions. A walk-through inspection of the buildings was made and some indoor climatic variables were measured. Some ocular and respiratory symptoms were related to water damage, damaged floor covering and mould growth.

Gypsum boards infested by Stachybotrys chartarum are often found in built-in constructions. A PCR-based analysis method has been developed for S. chartarum using specific primers based on the Tri5 gene. Another method for detecting fungi is by species identification via sequencing of ribosomal DNA. Sequencing of ITS (Internal Transcribed Spacer) and the 5.8 s rDNA is straightforward and provides a basis for species identification. The sequences were searched for by means of BLAST (Basic Local Alignment Search Tool) in the GenBank. The PCR technique will be an important step in the future both toward detecting fungal infestations at an early stage because of the ability to detect specifically the infestation without time-consuming cultivation in the laboratory and allowing reliable species identification based on sequences obtained from databases.

A birth cohort study (LARS - Leipzig Allergy Risk Children Study) was used to investigate the influence of indoor mould exposure on T cell function in early childhood. T cell cytokines (IFN-γ, IL-4) were analysed in a sub-group of the LARS cohort (birth: n = 39, 6 months: n = 11, 12 months: n = 50, 36 months: n = 33). Mould burden was assessed by analysis of questionnaires completed at the birth of the child and measurement of indoor mould spores was carried out when the children were 3 years old. Children whose parents reported mould burden or dampness in their dwellings at the time of birth showed lower amounts of IFN-γ producing Th1 cells during the first year of life (significant at 12 months) in comparison to unexposed children. The capacity to produce IL-4 was not altered, however. When the children were 3 years old, an association between measured indoor mould and suppressed Th1 reactivity was observed. The data suggest that indoor mould exposure is associated with reduced Th1 reactivity in early childhood.

Bronchoalveolar lavage (BAL) samples were taken in 47 patients whose symptoms were attributable to mould exposure and had visited the Clinic for Indoor Air Health Problems at the Helsinki University Central Hospital for a diagnosis of possible interstitial pulmonary disease. Tests showed that the total number of lymphocytes was elevated in 19 of these patients (40%). The percentage of lymphocytes in the cells from the lavage fluid ranged from 2 to 63% with a median of 19%. One patient had slight neutropenia.

The amount of endotoxin and (1 → 3)-β-D-glucan was determined indoors using four different sampling techniques. Airborne active related dust and floor-agitated dust had a lower proportion of endotoxin than sedimented surface dust. Endotoxin and glucan were related in airborne active related dust. An evaluation of the results in relation to effect data is required before recommendations on sampling methods can be issued.

A research project was initiated in order to collect numerical reference data on material emissions during the time of construction and to follow up indoor air quality in new buildings. Seven measurement sites representative of current construction practice in Finland were chosen for investigation. Material emission measurements for surfaces were made during construction using the field and laboratory cell (FLEC) technique. The emission rates for volatile organic compounds (VOCs), formaldehyde and ammonia and the relative humidity of the floor structure were measured for the floor structure build-up stages. In addition, decay behaviour of the emissions of underlying floor structures was investigated. The concentration of VOCs, formaldehyde and ammonia in indoor air and the air exchange rate were defined for the newly finished and 6 month-old buildings. The results were compared to indoor air concentration and emission rate target values defined in the Finnish “Classification of Indoor Climate 2000”.

In an epidemiological study of school children, we found that risk factors for asthma related to building dampness differed between children with and without a history of atopy.

Ergosterol was used as a marker of fungal biomass and 3-hydroxy fatty acids were used as markers of bacterial endotoxin to determine microbial colonisation of building materials by gas chromatographymass spectrometry. Pieces (0.3-0.5 g) of materials from two water-damaged buildings were hydrolysed to liberate the markers from larger microbial structures; the preparations were then purified, derivatised, and analysed. The marker patterns obtained revealed that the microbial communities differed between the two buildings both qualitatively and quantitatively. The chemical-analytical method described should be useful for detecting and characterising microbial colonisation on surfaces in, for example, damp buildings.

To test the hypothesis that mycotoxins may be the agents responsible for the allergy mediating effect of moulds, the effect of gliotoxin and patulin on T cell functions, especially the Th1/Th2 balance and subsequent IgE production, was investigated using cell models. In the presence of gliotoxin or patulin, anti-CD3/CD28/CD40-stimulated human peripheral blood mononuclear cells (PBMC) showed a suppressed IFN-γ secretion, whereas IL-4 was not affected or even stimulated (strongest between 1 and 10 ng mL¹ mycotoxin). The observed T cell polarisation toward the Th2 phenotype was accompanied by upregulated IgE synthesis. In addition, both mycotoxins reduced the allergen-specific (birch pollen) expression of IFN-γ mRNA, while IL-4 mRNA expression was unaltered or enhanced (significant for 10 ng mL¹ patulin). These data suggest that the mycotoxins gliotoxin and patulin may enhance allergic responsiveness.

A glazed atrium is a common feature in shopping centres and in the lobbies of residential and commercial buildings. This research aimed to discover the vertical temperature distribution and cooling load reduction relating to displacement ventilation in atrium spaces. The air temperatures at different levels (0.1, 0.7, 1.2, 1.7, 3, 5 and 7 m), within a 25 m high exhibition atrium, were monitored. Using the measured surface temperatures as boundary conditions, three-dimensional computational fluid dynamic (CFD) simulations were performed to examine the vertical temperature distribution. Further, by using parametric studies, the influences of occupant load, equipment load, lighting load, floor and wall surface temperatures, and supply air conditions were investigated with 12 CFD simulation cases. Based on the simulation results, load reduction factors - with three grouping methods of heat sources - were then developed. Temperature stratification was present even under the condition of a low cooling load. Load reductions were lower for occupant and equipment loads than for a lighting load. The best grouping method was to consider the heat released from the floor as an individual group of heat sources, which is an indication that secondary heat from the floor should not be neglected during the design of displacement ventilation.

This paper presents a study of the performance of a floor-supply displacement ventilation system using computational fluid dynamics (CFD). The experiment was carried out in a full-scale environmental chamber with a floor-supply system to obtain reliable flow information for the validation of a CFD program. The validated program was used further to evaluate the performance of the floor-supply displacement ventilation system with different air change rates, diffuser numbers, furniture arrangement, and cooling loads. The evaluation criteria are thermal comfort level and indoor air quality.