Research done by the University of Helsinki (2017) aimed to find whether adverse health effects of building related sickness (BRS) could be correlated with harmful indoor contaminants. These include molds, mycotoxins, and volatile organic compounds, all of which have all been associated with building related sickness (BRS). Despite this, it has been challenging to show a definitive correlation between the adverse health effects and these contaminants.

15 schools were chosen to represent different decades of construction and different building methods. Six of the schools had no earlier records of problems or complaints. The schools had different ventilation systems (natural ventilation, mechanical exhaust ventilation, or balanced ventilation system). Teachers in these schools answered a questionnaire to assess possible BRS experiences. Dust was collected from the classroom surfaces as well as from airborne fallout. The toxicity of the samples were measured using boar spermatozoa, which was exposed to different levels of dilutions of the dust and the biomass of fall-out samples for 3 days.. The motility of the spermatozoa were then examined by microscopy to determine the lowest exposure concentration at which > 50 % of it had lost motility.

The results showed, that:

• The number of BRS was 2.8-fold higher in classrooms with higher toxicity (p < 0.001)
• The number of symptoms alleviated during vacation was higher in the more toxic school classrooms (for wiped dust samples RR=1.9 and p=0.03; and for dust fallout RR=1.8 and p < 0.001)

The presence of harmful substances from the classrooms that directly (via dust) or indirectly (via cultivation of airborne propagules) impaired the motility of boar sperm cells were associated statistically significantly with work related BRS of teachers. As this was the case for both exposures of long term dust accumulation and short term fall-out, researchers suggest this indicates a link between microbial substances and BRS opposed to only e.g. VOC or cleaning products. The motility of the spermatozoa is based on a similar structure as motile cilia of somatic cells in humans. As the cilia are responsible for the mucociliary cleaning of the airways, a decrease in their function promotes inflammation and leads to illness.

The researchers also assess the issue of why this correlation hasn’t been confirmed  on earlier studies. The methods used before have been based on microbial DNA, but as of this study, it seems that it is the metabolites produced by the microbes rather than the microbes themselves that are important for BRS.