Laboratory trials were performed in order to search for the variety of the production ofmicrobial volatile organic compounds (MVOC), which could be used as indicators for hiddenmould damage. Concerning the MVOC production the experiments showed a dependency onthe building materials used as substrate and on the genus or species. It could be proved thatthe production of certain MVOC is not consistent at all times. On the whole low emissionrates in terms of g h-1 of the MVOC were found.

Research has suggested associations between indoor microbial exposures and respiratorydiseases across the globe. This aim of this study was to examine whether microbe levels wereassociated with housing characteristics. Study homes were selected from a prior citywidesurvey, and housing characteristic questionnaires were distributed afterwards. Airborne fungi,bacteria and dust samples were collected. Samplings were conducted every month for a year.Having pets at homes and age of the house were found to affect the indoor concentrations ofDer p 1 and Der p 2.

This presentation will review two major microbial cell wall agents (MCWA) - endotoxin and (1->3)-ß-D-glucan - concerning their toxic effects after inhalation and their role for the development of symptoms among persons in buildings with humidity problem.

Accurate and informative sampling methods are very important in the evaluation of fungalexposure in indoor air quality (IAQ) investigations. We have investigated the relationshipbetween indoor culturable airborne and dust-borne fungi and compared the performance ofculturable and non-culturable air samplersReuter Centrifugal Air Sampler (RCS) and ZefonAi-O-CellTM (AOC).

In buildings growing conditions for mould fungi can occur and cause fungus infestation. Thepossible danger for the occupants of dwellings lies in the production and spreading ofpathogens (disease causing agents). Therefore, consequent measures have to be taken to avoidhealth dangers that result from mould fungi in buildings. A strategy has to be set up thatfocuses on the growth conditions for mould fungi and also considers the complex transientprocesses of building physics.

Novel indoor air purification technology using ions generated by discharge plasma has beendeveloped. The effect of ions on airborne influenza virus has been investigated by the plaquemethod using MDCK cells and the hemagglutination test. It has been discovered that theseions can inactivate influenza virus in air world first. The infection rate of influenza virus toMDCK cells has been drastically reduced with the use of ions generated by the developeddevice. Furthermore the efficacy tests of these ions for polio virus and coxsackie virus havebeen performed.

A novel indoor air purification technology using ions generated by discharge plasma hasbeen developed. With the application of AC voltage between electrodes, dischargeplasma has been occurred and positively charged ions and negatively charged ions havebeen generated at atmospheric pressure. The chemical compositions of the ions have beenclarified to H + (H2O)m and O2 (H2O)n by time-of-flight mass spectroscopy.Bacteriostatic and fungistatic effects of these ions have been investigated.

Microclimates in moisture chambers and environment in houses were evaluated using afungal index. The index was calculated from the growth rate of a sensor fungus in a test piece,fungal detector, during an exposure period to the test environment. In the constant climates inthe moisture chambers, higher indices were obtained at higher relative humidity. In the roomswith higher fungal indices, the densities of airborne fungi were higher, indicating arelationship between the index and fungal contamination.

Microbial growth has been known as one of the major problems related to IAQ inresidential and commercial buildings. International and local standards define theupper limits of indoor relative humidity in order to avoid moisture related problems.However, setting limits on indoor relative humidity does not guarantee a mould-freeenvironment.

Japanese Building Maintenance Law defines that indoor humidity shall be maintained not lower than40%. But it is sometime very difficult to comply with the law. Indoor air humidifies in office buildingsmostly below 40% especially in wintertime. A request to deregulate the provision arises from HVACindustries. But a question concerning risk to deregulate the lower limit of humidity is arising.According to researches in 1960s, activity levels of influenza virus become higher when indoorrelative humidity becomes lower than 40%.