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.

Describes a survey carried out to investigate microclimatic conditions and microbial contamination in two office buildings with and without central air conditioning. Measured indoor climate factors generally fell within acceptable ranges for the mechanically ventilated buildings, except for the winter sample where relative humidity was low. Microclimatic parameters showed seasonal variation in the naturally ventilated building, and bacterial and fungal contamination was higher.

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.

The study collected water samples from 33 of 54 HVAC humidification system water reservoir pans in a large office building. The nature of the contamination that was found indicated that cleaning was ineffective, and may increase the risk of biological contamination. Of the two different humidification systems, air wash and steam injection, the air wash system revealed high contamination of samples.

Documents a study of airborne fungal concentration in a newly constructed building on the Gulf coast. States that fungal concentrations indoors were consistently below those outdoors, and samples did not clearly indicate contamination in the building, although visible growth was evident in the ventilation system. Concludes that the intrusion of most of the outdoor fungal aerosol is prevented by modern mechanically ventilated buildings, and that even extensive air sampling may not give the whole picture.