English

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.

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.

Describes a study carried out to investigate the possibility of suppressing microbial contamination of circulating water in humidifiers by using the oligodynamic potential of silver ions. Puts forward basic hygienic requirement to ensure adequate quality of water in humidifiers of air conditioning plant.

Following a sensory panel assessment of perceived air quality, proposes the use of a simple measurement method based on a dilution system connected to a ventilated small-scale test chamber in order to characterise the emissions from materials in sensory and chemical terms.

Explores possible relations between symptoms of asthma, building characteristics and indoor concentration of volatile organic compounds in residential buildings. 88 persons from middle Sweden were studied. Measurements were taken at home of room temperature, air humidity, respirable duct, carbon dioxide, VOCs, formaldehyde and house dust mites. Health tests were also performed. Found that symptoms related to asthma were more common in homes with house dust mites and visible signs of dampness or microbial growth.

Describes a study of the emissions from five commonly used building products: three floor coverings - PVC, floor varnish on beechwood parquet and nylon carpet on a latex foam backing; an acrylic sealant and a waterborne wall paint on gypsum board. Small scale test chambers were used over 50 days. A sensory panel was used to assess odour intensity and VOCs were measured. Emissions were studied under two or three different area-specific ventilation rates.

The most important indoor particle sources in the four single family homes studied were found to be cooking, cleaning and the movement of people. The sources contributed significantly to indoor concentration and to altered indoor particle size distributions. Air exchange rates ranged between 0.12 and 24.3 ach and impacted on indoor particle levels and size distributions.