The study examined emissions from dust collected on 2 stages ventilation filters in winter in Helsinki or in its outskirts. The filters contained a lot of fresh particles due to traffic, combustion, and power production. The carbon content was highest in the dust, which was collected from a pre-filter. In previous studies, the intensity of odors from filters was found to be strongest in the winter.
The study compares on 30 ventilation systems an hygienic factor determined from conditions at air intake (including moisture before and after drainage, porosity and contamination) and microbiological analysis of air. The aim is to identify ventilation systems potential risk for indoor air contamination.The study has shown a clear relationship between the microbiologic and the hygienic conditions; i.e. dry and clean intakes are less likely to be microbially contaminated. The method seems to identify potential problems, which could be confirmed by a microbiological study.
This study presents a literature review on oil residues on HVAC components. A sampling of oil residues by filter contact method and analysis by infrared spectroscopy method have been developped. Amounts of oil residues on surfaces of components varied a lot (<10 mg/m to 700 mg/m) but were significantly correlated to odour intensity. Cleaning of oil residues from the duct surfaces with typical cleaning methods is very difficult and it is better to deliver from the manufacturer components free of oil residues.
The study monitored two similar ventilation systems with fine filters during a few months, one operating continuously, one only during day time. Air, surface and filter material samples were taken to evaluate the extent of microbial contamination with viable fungi and bacteria. Filter and air of the permanent system,with higher relative humidity, were less contaminated by microbes and the contamination was more evenly spread in the filter.
A two-years old filter was placed in a ventilation system recirculating the air in an experimental space. Via glass tubes air was extracted to an adjacent room to allow a panel to evaluate the sensory load after facial exposure, without entering the space. The sensory pollution load of the filter determined from full exposure was approximately 7 times lower than when determined after facial exposure. Even though, used filters may still be important sources of indoor air pollution.
In an environmental lab with a panel of 30 women exposed 4 hours, comfort and health have been detremined both with a used or a new filter present in the ventilation system. All other environmental parameters were kept constant. A used filter in a HVAC system can have a negative effect on both the immediate perception of the indoor air quality and on perceptions and health-related symptoms. However, the annoyance experienced through the sensory system may have amplified the intensity of symptoms.
Design of thermal and air environment for large spaces is often realised with CFD simulations but due to measurement difficulty there are few cases in which results are compared after construction. This study uses a simple method for visualizing air currents and for estimating distribution of air movements with balloons.
Two aluminium windows were tested to determine the fractional penetration of airborne particles. Results show that mainly particles of 0.2 to 3 microns enter through both windows.
Particle penetration into an unoccupied research house was investigated through measurements under different conditions. Onmy particles with aerodynamic diameter of 20 to 3000 nm enter the house in significant quantity.
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