English

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.

A study examined by chemical analysis (without prior culture) bacterial levels in dust collected from hospital air conditioning filters. Gas chromatography-mass spectrometry methods were used to analyse the dust. Concludes that there is potential for the chemical assessment of the microbial content of airborne dust.

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.

Identified thermophilic actinomycetes contamination of the forced air systems as the sensitizing agents for most of the cases of hypersensitivity pneumonitis in eight patients. Concludes that patients should avoid the contaminated systems and use corticosteroids in severe cases as therapy for the disease.

Describes a study of indoor aeromycota in 15 homes in Canada. Significant differences in airborne spore concentrations were found in the different types of room. Living rooms held the highest count of airborne propagules, followed by family rooms, kitchens, bathrooms and bedrooms. Kitchens had the greatest variety of fungi. Increased numbers of spores were the result of dampness and carpets, in general. Concentrations of airborne fungi were found to be reduced by the presence of forced air heating systems, humidifiers, air filters and air conditioners.

An investigation of the source of an MRSA outbreak at a UK hospital found that the cause was an intermittently operated ventilation system. Ventilation grilles were found to be contaminated with EMRSA-15. It was found that daily system shutdown was causing a temporary negative pressure which drew air in from the ward and likely contaminated the outlet grilles. The index for the outbreak was a patient moved into the hospital from another large hospital. States that it is likely that contaminated air was blown back from the grilles at switch-on.

The effect of residential central air conditioning on indoor spore counts was investigated. Six pairs of residential buildings were monitored for three days. The homes were both air conditioned and non-air-conditioned. An Andersen sampler was used and outdoor measurements were also taken. Kitchens and bedrooms of air conditioned homes revealed significantly lower spore counts. The study used multiple regression analysis to show that the lower spore counts were associated with lower relative humidity.

In a laboratory chamber experiment, acoustic and thermal fibreglass insulation materials used in HVAC systems were colonized with fungi, which produced odour-giving volatiles. Suggests that these volatiles may be implicated in experience of indoor air quality and sick building syndrome symptoms.

States that on using the ELISA inhibition test against Aspergillus fumigatus, the study found that air samples from air conditioned rooms showed inhibition of the serum activity of a highly sensitized patient. Concludes that although an important fraction of aeroplankton particles can be filtered out of air conditioning systems, airborne allergens can nevertheless pass both coarse and fine filters.

Deterioration of air conditioning system in a hospital in Boston was found to derive from a strain of Pseudomonas sp. on heat transfer tubes of the closed chilled water system. Growth was stimulated by ethylene glycol antifreeze. The source was a warm expansion tank. The organism has been related to hospital-acquired infections.