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Exposure to Bioaerosols
Principal investigator: Aino Nevalainen, docent, Ph.D. National Public Helath Institute, Laboratory of Environmental Microbiology, e-mail aino.nevalainen@ktl.fi

Moisture and mould problems of buildings are associated with respiratory symptoms and diseases. The association between the building damage and the adverse health effects is well known, but little is known about the mechanisms of the diseases and about the actual exposure causing these health effects. The exposure has been characterized in many indirect methods. It has been shown that concentrations of viable fungi and bacteria and microflora of the indoor air in a damaged building differs from that of a normal building. However, viable microbes only comprise about 10% of the total number of biological particles in indoor air, and thus are a proxy of the real microbial exposure, the nature and quality of which is largely unknown so far. Toxic components derive from fungi and bacteria growing in building materials, but it has not been shown how the exposure to these components via indoor air takes place. The principal aim of this study is to find out whether the exposure to bioaerosols and fine particles of individuals with symptoms typical to mould exposure differs from that of matched control individuals. The detailed aims are:

1. To study whether the exposure to viable microorganisms, total number of biological particles and fine particles of the individuals with mouldy house symptoms differ from the exposures of matched control individuals with no such symptoms

2. To study whether the same inflammatory mediators which are detected in the nasal lavage fluid of exposed individuals, can also be detected in vitro in the cell culture medium of macrophages after the exposure to particles, collected during the exposure period.

3. To study the within person and between persons variation of exposure to bioaerosols using repeated measurements.

4. To compare results of personal exposure and stationary sampling measurements in home and work.

A group of 35 individuals with symptoms typical to mould exposure will be selected and a control individual with no such symptoms will be selected for each index person. A 24-hour sample collection for bioaerosol and fine particles will be made with personal and stationary sampling in homes and in the working places. The homes and working places will be surveyed for signs of moisture damage according to a check list. During the sampling period, diaries on time activity in different microenvironments and on symptoms will be filled and PEF will be recorded. A nasal lavage fluid sample will be taken from each individual after the sampling period. This sampling period will be repeated twice with each individual.

Bioaerosol and particle sampling is made with button samplers developed in the University of Cincinnati.The concentration of collected particles will be analyzed gravimetrically. Viable microorganisms of filter are cultured and the total number of biological particles counted with an epifluorescence microscope.

Toxicological studies: A nasal lavage fluid (NAL) sample will be collected from each individual after the sampling period. Production of inflammatory mediators (NO, cytokines: TNFalfa, IL-1, IL-5, IL-6, IL-10) in the NAL cells will be analyzed.