In this study, the odor generation of various components of air handling units was investigated. Results how that air handling system really can deteriorate the perceived air quality of the supply air. Almost all components seem to be sources of pollution, but differences between the components were significant. Used fiber filters seem to be the worst. A major reason for the pollution seem to be oily, dusty, and dirty surfaces.

Samples of surface dust were collected from ducts before and after an HV AC system cleaning project in an office complex in Canada. Dust levels were quantified gravimetrically and concentrations of viable fungi were determined (1) using a standard dilution plating method from vacuum-collected surface dust samples; and (2) by the collection of surface samples on commercially available agar contact slides.

The aim of this experiment was to study the effect of air duct cleaning on the indoor air quality. Three buildings in the Helsinki metropolitan area were selected for the study. In two of the test buildings the ducts were cleaned using three different cleaning methods. The third building serves as a control where no cleaning was done. The air handling systems in the test buildings had operated 26 and 30 years without cleaning.

In this study, the effect of duct cleaning on the indoor air quality and on the ventilation system hygiene in non-problem office buildings: was investigated. Six office buildings were selected from local duct cleaning companies' contracts. A questionary was distributed among the occupants prior to and after the duct cleaning. Also several air quality parameters were measured in outdoor air, indoor air,· and supply air and ventilation system hygiene measurements were performed prior to and after duct cleaning.

The aim of this experiment was to compare three measuring methods to determine the level of dust in air ducts. Compared methods were a vacuum test, a tape method and an optical method. The dust samples were taken from the supply air ducts of new buildings. The paper presents and compares the results of the tests. The samples were taken from three day-care centers in the Helsinki area. The ducts were not cleaned after the manufacturing process or protected during the construction. Duct surfaces had also oil residues from the manufacturing process.

Although a significant amount of work has been done to elucidate the conditions under which fungi will grow on the surfaces of materials, little information is available that quantitatively relates surface concentrations to airborne concentration and, ultimately, exposure. This paper discusses the impact of relative humidity (RJI), air velocity, and surface growth on the emission rates of fungal spores from the surface of contaminated material.

The aim of the experiment was to study the efficiency of three duct cleaning methods. The methods used were ( 1) rotating brushes, (2) compressed air cleaning, and (3) wiping by hand. The air handling systems under investigations had been in use 26 and 30 years after the construction phase and the systems had not been cleaned since buildings were completed. Accumulated amount of dust in the supply air duct was determined by BM-Dustdetector, tape method, and by visual inspection before and after cleaning. The amount of dust on the duct surface was decreased with all three cleaning methods.

The new Guideline VDI 6022 contains hygienic standards for ventilation and air-conditioning systems. The requirements for the planning, design, operation and maintenance of ventilation and air-conditioning systems and their components are dealt with to ensure a hygienic condition according to the state of the art. The Guideline is subdivided as follows:

• part 1 Offices and assembly rooms (published 07 /98)
• part 2 Standards for Hygiene training (published 12/98 as a draft)
• part 3 Factories (activities have been started 01/99)