DEVELOPMENT OF METHODS TO MONITOR THE SUCCESS OF REPAIR MEASURES

Project leader: Aino Nevalainen, National Public Health Institute (KTL), Laboratory of Environmental Microbiology, P.O.Box 95, FIN-70701 Kuopio, Finland, tel. +358-17-210 342, e-mail: Aino.Nevalainen*ktl.fi
 
 

PUBLICATIONS

TIIVISTELMÄ SUOMEKSI

Researchers:
Ulla Haverinen, National Public Health Institute, Department of Environmental Health, tel. +358-17-201 211, e-mail: Ulla.Haverinen@kt.fi
Anne Hyvärinen, National Public Health Institute, Department of Environmental Health, tel. +358-17-201 211, email: Anne.Hyvarinen@ktl.fi
Tuula Husman, National Public Health Institute, Department of Environmental Health, tel. +358-17-201 211, email: Tuula.Husman@ktl.fi
Pekka Laamanen, Consulting Engineers Mikko Vahanen Ltd, tel. +358-9-563 761, e-mail: Pekka.Laamanen@inststo-vahanen.fi

Consortium: Moisture, mould and health
Financing SYTTY organization: Tekes, The Ministry of Environment
Funding from SYTTY / Total funding of project (€): 201825/ 417812
Person-months of work funded by SYTTY / Total person-months of work: 68 / 93

KEY WORDS: moisture damage, microbial growth, health effects
 

EXTENDED ABSTRACT

1 Introduction

Follow-up is an important part of a repair process. In the process, it is possible to use technical, microbiological and health measurements. However, there is lack of knowledge of how to assess the repairs and their effects in practical situations. Findings from few follow-up studies published have been promising in showing that comprehensive repairs decrease the exposure and symptoms of the occupants, providing that the repair needs have been evaluated correctly and the repairs have been done carefully as planned (Koskinen et al. 1995, Haverinen et al. 1999b). A central requirement is that the evaluation of the repairs is made reliably. Aims of this study were to develop and test evaluation methods for moisture and mould damage and their repairs, to develop co-operation between research institute and a private company, and to determine what documentation is needed for evaluation of repairs. We also aimed to develop recommendations for how to carry through a follow-up study. Several methods to study moisture and mould problems of buildings have been tested and further developed in this study as well as in other studies of this consortium. This study concentrated on gathering theoretical and practical information from the methodological point of view.

2 Material and methods

Methods to investigate moisture and mould problems of buildings include engineering measurements (building investigations), measurements of microbes and other pollutants from building constructions and/or indoor air (exposure measurements), and health effects studies of the building occupants. Building investigations may include non-destructive methods such as visual investigation, short and long term moisture measurements, and ventilation performance tests. On the other hand, building investigations may include the use of destructive methods such as structural openings. Exposure measurements may include use of air samples, surface samples and material samples, of which material samples are destructive from their nature (Hyvärinen et al., accepted for publication). Health effect studies may include use of questionnaires and clinical studies (Haverinen et al. 1999a). After repairs, the usability of destructive methods is limited, and therefore the focus of this study was in development of non-destructive methods: visual inspection of buildings, air sampling of viable fungi and bacteria, and test of toxicity from filter samples. In health effect studies, the focus was in the use of questionnaires, although clinical findings of lung function and allergic reactions were of interest in follow-up studies of school environments (Haverinen et al. submitted c, Immonen et al. 2001a, b).

Visual inspection method was further developed by modelling moisture damage and its association with occupant reported health symptoms (Chelelgo et al. 2001, Haverinen et al. 2001a, b, Haverinen et al. submitted a, b). An aim of the study was to improve the objectivity of the method in assessing moisture damage; criteria in assessing moisture damage based on their characteristics were established.

For case studies made in the field, five work environments were selected, where moisture related indoor air problems had been found, and where these problems were going to be solved by repairing the buildings. The study sites had to be occupied and large enough for health effect studies in a group level. Otherwise, these sites represent various types of buildings, and their use and organisational structures were different from each other (Haverinen et al. 2000). Therefore, also the decision-making and ways of actions were different, which all had effects on the repair processes. Methods used to follow-up the effect of the repairs were engineering measurements, exposure measurements and assessment, and health effect studies. Evaluation of the repairs was based on measurable change in the situation before and after the repairs. The possible changes were determined by visual observations, engineering measurements, microbiological situation of the building or state of health of the occupants. The study protocol was similar in all study sites, and the results after the repairs were compared with those before the repairs, and also with results from other, similar types of work environments.

3 Results and discussion

3.1 Use of engineering measurements
On-site building investigations are conducted for many reasons, among them to assess the suitability of a space for a particular group of occupants and to attempt to identify possible causes of complaints from current building occupants (Macher et al. 1999). The investigations typically starts with a building walkthrough, during which the investigators collect primarily observational data, e.g. information obtained by visual investigation of the building. The preliminary inspection may also identify the need for an in-depth building evaluation, during which investigators focus on potential problem areas and gather data to address specific questions (Macher et al. 1999, Haverinen et al. 1999a). During and after the repairs, the observational data is essential in assessing the repairs, whether the repair measures taken fulfil the needs by their extension and quality.

Based on our modelling studies, it seems apparent that observed moisture damage is an indirect and complex surrogate of exposure to microbial and/or chemical pollution caused by excess moisture on building materials (Haverinen, accepted for publication). Therefore, although obtaining evidence of specific exposures and their association between occupant health is difficult, a visual inspection made by experienced investigators may yield valuable information about the existence and qualities of sources of contaminants. As a result of the studies, a quantitative tool in estimating the severity of moisture damage in relation to health symptoms was devised (Haverinen et al. submitted a, b).

3.2 Use of exposure measurements
Measurements of pollutants in moisture and mould damaged buildings is mainly for a purpose to find and locate abnormal sources, which may contaminate indoor air of the building and result in exposures. For example, it is believed that based on careful analyses of the indoor / outdoor ratio of airborne fungal concentrations and the genera present, or concentrations and genera of bulk samples taken from local sites of contamination, it is possible to identify indoor sources of microbial growth. In assessing the success of the repairs, the use of exposure measurements is mainly based on the comparison between the situation before and after the repairs, and in practice, only air sampling can be used without limitations. Difficulties often experienced in assessing the exposure to microbes using air sampling are partly explained with temporal and spatial variation of fungal concentrations, which has proven to be high. Sampling days estimated to be sufficient to characterise fungal concentrations of residences or alike with unknown indoor conditions in winter is n=11 (Hyvärinen et al. 2001). Spatial variation can be taken into account by carefully planning the amount of samples, which is needed from a building, taking into account the size of the building. Temporal variation may be more difficult to control in practical situations, since it is not cost-effective to sample in several days in study sites. Temporal variation of fungal concentrations in air is strongly affected by season due to outdoor air levels (Reponen et al. 1992). In our climate, the contribution of outdoor air to the indoor air microbial levels is negligible in winter, since the outdoor levels are low due the snow cover on the ground. Thus, our climate provides a good possibility to study indoor sources. However, repair schedules are determined by several factors, and because of that, also summer time measurements may be required. In this study, we paid attention to interpretation of such results. It seems that in order to see the effect of indoor sources more clearly in assessing the success of repairs, the measurements after the repairs should be repeated in winter.

3.3 Use of health effect studies
Health effects among have usually been assessed by questionnaire, or clinical diagnosis, e.g. lung function and skin prick testing, have been used. Questionnaire is a relatively cost effective method in collecting information of occupant perceived indoor air quality and health symptoms, especially if the study population of interest is large. In the follow-up studies attention should be paid on the time needed for clearance after the repairs, as well as the recall period. Both of these, but also some other factors have effects on the time point when the study should be made. Because there is only a little information on the “normal” levels of symptoms, the interpretation of the results is mainly based on the comparison of the situations before and after the repairs, when the respondents can serve as their own controls. However, the use of this approach may be limited if the study population changes during the follow-up period (Haverinen et al., submitted c). To overcome this problem it is possible to use a corresponding control group. Both of these approaches were tested in this study. It appears that the effects of repairs can be seen by questionnaires, at least in the group level. Seeing the effects in the level of exposed individuals may be more complicated. Findings from the clinical studies have been difficult to interpret, which may be partly because of the responses are often unspecific and/or difficult to measure by the methods that are currently available (Immonen et al. 2001a, b).

3.4 Case studies
In the case study sites, the repairs were completed in four of the five buildings, whereas one of the buildings was left unrepaired after an earlier decision of evacuation of the occupants. The repairs were made comprehensively in one building, partly / focused in two buildings and in stages in one building. Follow-up studies were made in all of the sites: health effect studies in five, microbial follow-up in four, and engineering evaluation in three sites. Findings were on behalf of the success of the repairs in one building using microbial measurements, whereas in three buildings the results referred to some problems still remaining. Preliminary results from the health effect studies supported these conclusions. However, there are several factors that must be taken into account in designing the follow-up of repair processes in practical situations, part of which are difficult to control by the study design (Haverinen et al. 2000).

4 Conclusions

In practical situation, evaluation the success of repairs should be made by using non-destructive methods. Therefore, the focus is in visual inspection of buildings from technical point of view, and indoor air samples for exposure assessment. Health effect studies may be needed if the problem has been remained unsolved for a long time, and there is a risk for adverse health effects. We have been able to develop visual inspection method by means of its objectivity and quantitativity. The study group has also been able to assess the effect of temporal and spatial variation of fungal concentrations in indoor air, and develop a test of toxicity for filter samples. The use of questionnaires and clinical studies in health effect assessment has been evaluated. All of this information is readily applicable in follow-up studies. However, evaluation the success of repairs, and performing follow-up studies after the repairs have been made in practical situations, may not be possible unless several other factors affecting them have not been sufficiently addressed in the earlier phases of the repair process. These factors may involve assessment of the need of repairs, repair plans, work supervision and decision-making. Therefore, follow-up aspects should be incorporated with each stage of the repair process.

The material will be further analysed; the focus of which will be in the methodology. The results will be published in a comprehensive study report in domestic language, which is under work. The study report will be one of the main results of this study: it is needed in the field to be able to carry out and document successful repairs. In addition, various scientific publications have been written by the study group, supporting the theoretical framework of the study.

5 References

Koskinen O, Husman T, Hyvärinen A, et al. Respiratory symptoms and infections among children in a day-care center with mold problems. Indoor Air 5, 3-9, 1995.

Macher J, Ammann HA, Burge HA, Milton DKM, Morey PR, Eds. The building walkthrough. In: Bioaerosols: Assessment and Control, ACGIH, Kemper Woods Center, Cincinnati, Ohio, USA,
Chapter 4, 1999.

Reponen T, Nevalainen A, Jantunen M, et al. Normal range criteria for indoor air bacteria and fungal spores in a subarctic climate. Indoor Air 2, 26-31, 1992.
 
 

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