Field studies were carried out on air contamination by dust particles from air conditioning systems in four buildings in Tokyo area. We tried to investigate contamination of airborne particle and surface contamination by sedimentary dust in air duct, and considered a matter in all its aspects that caused indoor air pollution.

1. Time variations of airborne particle concentrations at supply outlet were influenced by the operation of air conditioning system.

A nine-home field study was conducted to investigate the impact of mechanical air duct cleaning (ADC) methods on indoor air quality (IAQ) and system performance. ADC services were provided by the National Air Duct Cleaners Association (NADCA). Only mechanical ADC methods were evaluated. Surface treatments, such as biocides or encapsulants, were not part of the study. Pre- and post-ADC measurements were used to evaluate impacts.

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.