duct cleaning

Coughing, throat irritation, shortness of breath and disorientation were experienced by employees of a communications firm, resulting in building evacuation. Describes how a multidisciplinary team analysed the source of the problem. Results suggested that the outbreak was due to multiple factors including microbial growth in the air handling system, chemical product use in the building, and insufficient outdoor air. States that psychosocial factors also played a role.

This study was based upon a laboratory comparison of two air duct cleaning methods, mechanical brushing and compressed air cleaning. These methods were compared in three types of round air ducts: a metal duct without oil residual, a metal duct with oil residual, and a plastic duct. The level of cleanliness was estimated both by using the vacuum test method and visually, and the time each method took was recorded. Two rotating speeds of the brush and various brush materials were used.

The project aimed to conduct research on the reasons for pollution caused by HVAC systems. It was found that the reasons vary widely depending on the type of construction, use and maintenance of the system. Filter and ducts are major sources of pollutants, with humidifiers and rotating heat exchangers coming a close second. Heating and cooling coils are less of a problem, as is the effect of air flow. Puts forward a new maintenance guideline based on the existing VDI 6022.

The emission rate of VOCs and aldehydes from materials typically found in ventilation ducts was measured. It was found to be low for some duct liners, but high for duct sealing caulk and a neoprene gasket - in fact approaching the odour threshold. Exposure to ozone was found to increase the emission rate of aldehydes from a duct liner, duct sealing caulk and neoprene gasket. When exposed to ozone, the removal efficiency for a lined duct diminished to less than 4% over 10 days. It was much lower for an unlined duct.

Used a trained sensory panel and chemical and microbial measurements to examine the odour generation of the various components of air handling units. States that the results revealed that the supply air perceived air quality can be affected by the system. Nearly all the components of the system were sources of pollution, with used fibre filters the worst, although there were significant differences between the different components. Oily, dusty and dirty surfaces were the worst sources. Increasing the airflow did not improve the perceived air quality downstream of the components.

Study aimed to assess the effectiveness of domestic air duct sanitation services in reducing indoor aeroallergens. Sampling for fungal colony forming units was carried out in eight residences in winter and seven in summer, before and after a local company carried out duct sanitation procedures. Two houses were used as controls. Baseline CFUs were similar in control and study houses. The study homes showed an overall CFU reduction of 92% in winter and 84% in summer, eight weeks after cleaning. The controls showed no reduction.

Analyses possible biocontamination of fibreglass duct materials used for thermal insulation and noise control in both residential and commercial heating, ventilation and air conditioning systems, in the light of concerns about the safety of their use in high humidity conditions. Static environmental chamber tests were carried out over six weeks to investigate conditions which might support the growth of a fungus, Penicillium chrysogenum.

Describes how laboratory experiments were conducted to assess the susceptibility of three types of ventilation duct materials to fungal growth. They were fibrous glass ductboard, galvanized steel, and insulated flexible duct. The results showed that only the flexible duct supported moderate growth of P. chrysogenum. The other duct materials showed no growth. Soiling with dust from residential heating and air conditioning systems increased the susceptibility of all three types, albeit at different levels of soiling, with the galvanized steel the least susceptible.

Two out of fourteen workers in a clerical office suffered bronchial problems. An investigation found gross contamination with Penicillium mould of forced-air heater-cooler units which had not been properly maintained. A 50 to 80 fold excess in the number of colony-forming units per cubic meter or air in the affected office compared with a control office were found. Persistent alveolitis was diagnosed in one worker, while the other suffered from asthma, exacerbated by the poor indoor air quality.

Regression techniques were used to assess the associations between environmental factors and work-related health conditions. The study used environmental and health data for 2435 persons in 80 offices. When adjusted for age and gender, relative risks for multiple lower respiratory symptoms were increased for variables in the HVAC design and maintenance categories, with the highest for presence of debris inside the air intake, and for poor or no drainage from drain pans. Multiple atopic symptoms were related to suspended ceiling panels. Asthma was related to renovation with new drywall.