FAI is based on air sampling and provides information on:
• Presence of a mould source
• Potential exposure to mould
• Potential exposure to total allergens
• Room cleanliness
What is the Fungal to Allergen Index?
The FAI concept is a tool developed to assist the visual (and odour) assessment that is the core of all mould inspections. Parallel air samples are analysed for total fungi and total allergens. The dual samples give information of both the potential exposure to fungi and to total allergens (dust mites, pollen, mould, pet dander, etc.). The core of the FAI concept is to calculate the ratio between the total fungi and the total allergens, and then from this ratio, predict the presence of a mould source. Results can be obtained in 1 or 2 hours and are objective and independent of individual evaluations from laboratory technicians.
FAI is an alternative to the traditional concept, looking at both quantitative and qualitative differences between the fungal population of indoor and outdoor fungi. FAI is also an alternative to the DNA based methods such as ERMI, which is also based on the classical assumption of certain fungal species being water damage fungi and other species being normal dust fungi.
More reproducible and representative sampling
At the IAQA conference in 2020 data presented, showed that activated air sampling (resuspending of settled fungal particles) gives more reproducible and representative results, and results that are independent of prior activity in the room. The interpretation criteria given in the FAI concept is based on an standardized sampling protocol using activated air sampling.
How to interpret results?
The figure below is shown the FAI results from a bedroom using activated sampling.
The Mycometer air value (MAV) for the fungi is 607 FLU per m³ of air. The number is high (a category C) compared to the population found in buildings with no visual signs (or smells) of mould growth or water damage (Data was presented at the IAQA conference 2021). The MAV for allergens is 17780, which is very high. The FAI value is 3% which is very low. The interpretation is that the level of mould and therefore the potential exposure to mould is in the high end. The level of total allergens is very high. This can most often be interpreted as a poor cleaning standard and involves a high potential exposure to allergens. Even though mould and allergens are high the FAI value are very low indicating that the is no mould source.
The figure below shows 3 samples where the FAI value is very high. This is a very strong indication of the presence of a mould source in, or in the vicinity of the room. Notice, however, the high variability in the mould levels ranging from 186 to 3107. This demonstrates that the quantification of mould alone is not necessary a good indicator of the presence of a mould source. But the potential exposure is off course almost 17 times higher in the kitchen than in the living room.
The figure below shows 3 samples where the FAI value is low to normal. It is unlikely therefore, that there is a mould source in or in the vicinity of the room, that feeds significant mould particles (spores and hyphal fragments) into the room. Again, even though the level of mould is 20 times higher in the bedroom than in the bathroom the conclusion is the same. This variation can be explained by a difference in the cleaning standard (measured as the variation in the total allergen level). The level is 36 times higher in the bedroom compared to the bathroom.