English

Mycological investigations were performed on a modern multistorey office building in the southeastern coastal US. Extensive colonization was found in the air handling units and fibreglass duct liner of the HVAC system. Concentrations in air samples were low however. Removal of colonized insulation material reduced indoor air quality complaints.

Describes a project to examine the secondary air filters in the air handling units on four floors of a multi-storey office building which had a history of fungal colonization of insulation in the air distribution system. Fungi were observed throughout the system. Lower concentrations of volatile organics were emitted from fungal affected air filter medium. Concludes that the growth of fungi in air distribution systems may affect the content of volatile organics in indoor air.

Measured ozone decay rates were found to be significantly correlated with house type and the number of bedrooms for a monitoring project of 43 California homes. The observed decay rates were higher in multiple-family homes and homes with fewer than three bedrooms. Homes with higher surface-area-to-volume ratios had higher decay rates.

In order to determine whether high outdoor ozone concentrations are transferred to the indoor climate of museums, a monitoring project was carried out on eleven museums, art galleries, historical houses and a museum library for 38 days over the summers of 1984 and 1985. The differences in indoor ozone levels between the buildings could be explained by differences in building and ventilation system design, and this was verified by a mathematical model. Peak indoor ozone levels were highest in building with no air conditioning but a high rate of air exchange with the outdoors.

The study investigates the effect of mechanical ventilation and high-efficiency vacuuming on house dust mite numbers and allergen concentrations in dwellings of mite-sensitive asthmatics. Of forty houses, some received mechanical ventilation, some an HEVC, and some both, while a number acted as controls. The monitoring exercise lasted for twelve months. It was found that humidity was reduced in homes with mechanical ventilation and mite numbers reduced accordingly. Use of the vacuum cleaners enhanced the effect.

A move to mechanically ventilated low-dust mite affected, 'healthy' homes was investigated in relation to asthma control. Fourteen patients, allergic to dust mite allergens, were studied. Clinical improvements were significant in the patients, in contrast to the control patients. The study found a significant relation between reduction in medicine score and the fall in house dust mite exposure.

Describes a study of 424 homes in USA to analyse the presence of dust mite allergens. Seasonal fluctuations were identified. Air conditioning was found to reduce allergens. States that the findings imply that differences in the microclimate within homes may have a dramatic effect on mite populations.

Public facilities in Japan were investigated for the presence and distribution of allergenic mites. Dust was analysed from four hospitals, two hotels, two ryokans, one film theatre and four office buildings. Clinically important antigen levels were found in the theatre, and ryokans, but not in the hospitals, hotels or offices.

Attempts to determine the influence of the installation of highly insulated windows and central heating systems on indoor climate, and mite-allergen (Der f 1) and mould spore concentrations. A before and after study was carried out on 98 apartment bedrooms, with measurements taken of air exchange rate, temperature and humidity. A lifestyle and housing conditions questionnaire was undertaken by the occupants and dust on carpets and mattresses was analysed for mould spores and Der f 1.

Thirty asthmatic patients were tested for exposure to house dust mites before and after moving to mechanically ventilated homes. There was found to be a significant reduction in house dust mite numbers after four months in contrast to the control group of 23 patients. A further reduction had occurred after 15 months. Air change rates increased from 0.40 ACH to 1.52 ACH. There was also a reduction in absolute air humidity.