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| 2. |
- Mattsson, Magnus, et al.
(författare)
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Mixing and displacement ventilation compared in classrooms; distribution of particles, cat allergen and CO2
- 2003
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Ingår i: Proceedings from Healthy Buildings 2003. ; , s. 458-464
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Konferensbidrag (refereegranskat)abstract
- Mixing ventilation and displacement ventilation were compared in an intervention study in classrooms. Particles, cat allergen and CO2, were measured in classroom air at different levels above the floor, during regular lessons. With mixing ventilation, the particle concentration tended to decrease with height, with a stronger gradient occurring for larger particles. With displacement ventilation, the particle concentration increased with height, except for particles >25 µm. The displacement system thus tended to have a slight upward displacement effect on most of the particles. Significant correlations were found between concentrations of cat allergen and particles in the size fraction 1–10 µm. The particle and cat allergen concentration at breathing height did not, however, differ significantly between the two ventilation systems. CO2 was about 10% lower with displacement ventilation. A fairly high level of physical activity of the pupils is believed to have had significant dispersing effect on the airborne contaminants.
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| 3. |
- Mattsson, Magnus, 1964-, et al.
(författare)
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Ventilation filter efficiency for birch pollen allergens : experimental data from one pollen season
- 2011
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Ingår i: Proceedings from Roomvent 2011. - Trondheim : Tapir Akademisk Forlag. - 9788251928120
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Konferensbidrag (refereegranskat)abstract
- In an experimental study, ventilation filters of high quality (F7 & F9) were tested regarding their efficiency in collecting birch pollen allergens in outdoor air. The birch pollen grain concentration in outdoor air was measured at the same time as pollen allergen and particle number concentrations were measured before and after the tested ventilation filters, thus enabling collection efficiency calculations. Simultaneously, the size distribution of birch pollen allergens was measured in outdoor air using a cascade impactor. The study confirms previous indications that pollen allergens may occur in outdoor air in particles much smaller than pollen grains, and can penetrate ventilation filters to a larger extent than might be expected. This entails that although the high quality filters collect most of outdoor air pollen allergens, a significant exposure dose to these allergens can occur in the indoor environment, especially when considering the fact most people stay much more indoors than outdoors. The study also confirms previous similar indications attained with grass pollen allergens, in that the allergenic particles tend to penetrate ventilation filters to a greater extent than other airborne particles.
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| 4. |
- Mattsson, Magnus, 1964-, et al.
(författare)
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Ventilation filter efficiency for particles and grass pollen allergens
- 2009
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Ingår i: Proceedings of the 9th International Healthy Buildings Conference and Exhibition.
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Konferensbidrag (refereegranskat)abstract
- In an experimental study, commonly used ventilation fine filters were tested regarding their efficiency in collecting airborne particles and grass pollen allergens from outdoor air. Grass pollen allergen and particle number concentrations were measured before and after the filters, enabling collection efficiency calculations. Simultaneously, the size distribution of grass pollen allergens was measured in outdoor air using a cascade impactor. The study confirms previous indications that pollen allergens occur in the outdoor air as particles much smaller than pollen grains, and can penetrate ventilation filters to a larger extent than might be expected. The initially high collection efficiency of synthetic, electrostatically charged filters declined significantly with time of use (dust load), whereas glass fiber filters showed steady performance. A slight tendency for pollen allergenic matter to penetrate ventilation filters more than other airborne particles was noted, but no difference in the response to electrostatic charge of filters could be seen.
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