The survival of bacterial and mould spores in new and used air filter media is explored. Samples of different media were challenged with specific microbial aerosols in a filtration test unit, and the viability of the microorganisms collected in the filter media examined. In five days there was no noticeable decrease or increase in the viability, nor did relative humidity have an influence.

In seven hospitals in the eastern United States air filters of various types, selected by discoloration, were collected from the primary and secondary filter banks of the HVAC systems. The samples were then examined with direct microscopy for fungal colonization. Results showed that filters from five of the hospitals were colonized with fungi. Several of the species had not previously been reported to colonize air filters.

Describes how new and used cellulosic air filters for HVAC systems including those treated with antimicrobials were suspended in vessels with a range of relative humidities, and containing non-sterile potting soil to stimulate fungal growth. Prior to suspension in the chambers most filters yielded fungi, but only two of 14 non-treated filters demonstrated fungal colonization following use in HVAC systems. Antimicrobial-treated filters, in particular a phosphated amine complex showed a lot less fungal colonization than nontreated filters.

Sensitizations to fungi that can be isolated when the fungi are removed from air conditioners are often shown by people suffering from various symptoms while in air conditioned rooms. It was shown that by using specific challenge tests fungal spores in air conditioners can give rise to allergic symptoms. The specific therapy prescribed for these reactions was hyposensitization. After this therapy, more that 70% of the patients could live and work again in air conditioned rooms without developing symptoms.

In the study a collection was made of bacterial and fungal spore samples from twelve office building ventilation systems. Measurements were performed with and without humidification. In none of the cases were ventilation or humidification systems found to act as bioaerosol sources. There was no observed difference between bioaerosol counts in offices with and without humidification. In all ventilation systems the microbial levels decreased.

An examination was conducted of thirty single family homes with either high or low house-dust mite allergen levels in mattress dust, with regard to ventilation, thermal climate, and air quality. High concentrations were associated with the difference in absolute humidity between indoor and outdoor air, also with low air change rates, especially in the bedroom. The research found no correlation between concentrations of TVOC or formaldehyde in bedroom air and HDM allergen concentration.

Describes and investigation of house-dust mites in 96 Danish homes with one or more members with asthma. All the homes were measured for air exchange rates, humidity and temperature. The study found a positive correlation between indoor air humidity and mite concentration and an inverse correlation between house-dust mite concentration and indoor air exchange. House-dust mite concentration was higher in the houses with mite-allergic persons. In 76% of the homes the concentration was above the proposed limit of 10 mites/0.1 g dust. This was so in 48% of the non-allergic homes.

An experiment was performed in a lecture hall on students, to assess the effect of ventilation noise on concentration and fatigue. The students were tested with the ventilation fans both on and off. As a group the students reported more fatigue during lectures when the fans were operating. States that this environmental effect explains about 39% of the variance in fatigue ratings and may be sufficient to affect adversely the attention of students within these settings.

The effectiveness of individual commercially available portable indoor air cleaning units were tested for their removal of dust particulates, tobacco smoke particulates and vapour phase constituents, viable and total fungal spores, pollen, and gaseous contaminants, and formaldehyde. A clean air test chamber was used. The results presented represent initial use. It was found that HEPA and electrostatic precipitator system demonstrated the highest efficiency in relation to particulate contaminants, with electret filter systems close behind. Least effective were ionizers and ozone generators.

Assesses sick building syndrome symptoms and perceived odours for daycare workers, in relation to ventilation rates in Finnish daycare centres. Thirty centres were chosen for the study, which consisted of 268 female nursing workers. The workers completed a questionnaire. Mechanical supply and exhaust ventilation systems constituted most of the centres' systems with 37% having mechanical exhaust alone. The authors noted a very varied exhaust air flow in the children's rooms, from 0 to 11 L/s per person. Air change rate varied from 0 to 5 m3/hm3.