An attempt was made to find any association between employees' respiratory tract symptoms and immediate skin test reaction with exposure to fungal and house dust mite aeroallergens at the workplace. Six mechanically ventilated non-industrial buildings were considered in Montreal. Concludes that potentially avoidable exposure to aeroallergens accounted for symptoms in a small subgroup of office employees with frequent work-related respiratory tract symptoms.

Describes the investigation in 1994 of a suspected case of sick building syndrome at a communications centre. The building's central HVAC systems had a poor record of maintenance, and there had been continual structural modifications to the building. Inspection revealed the presence of fungal growth in the HVAC system. Remediation included employing a dedicated mechanic to implement a preventive maintenance programme. A significant drop in fungal concentrations was revealed as a result.

The study described attempted to assess the relative efficacy of personal respiratory protection when infectious aerosol concentration increases or room ventilation rates decrease. A variable for respirator leakage was added to the Wells-Riley mathematical model of airborne transmission of disease. States that infection risk decreases exponentially with increasing room ventilation or personal respiratory protection. As room ventilation rates increase, or concentrations of infectious aerosols decrease, the relative efficacy of personal respiratory protection decreases.

In order to examine the possible effects of humidifier use on asthma control, a randomised controlled study was performed. No significant differences were found when analyses were restricted to portable humidifiers, allergies to mites and/or moulds, and infrequently cleaned humidifiers.

The authors used data from the Children's Respiratory Study in Tuscon, Arizona, USA to study the relationship between home environment and lower respiratory tract illness in infants. Health babies were recruited at birth. In the first year, 196 babies (21%) had wheezing LRI and 60 (6%) had non-wheezing LRI. Wheezing risk was higher for babies with evaporative home cooling (24%). Non-wheezing LRI linked with parents' rating of neighbourhood dust levels. There was no relation to type of home heating, cooking fuel, or pets.

Describes the microbioligic surveillance of the central air handling systems in a hospital, prompted by an increase in the rates of nosocomial infection caused by filamentous fungi in immunocompromised patients. Heavy contamination by Penicillium was found in ventilation ducts and terminal unit lined with fiberglass in the operating room air handling system, as well as Aspergillus species. The contamination was corrected using filter replacement and decontamination with aerosolized chlorine solution.

A children's day care centre in Finland was the site of a study on the effect of ventilation and air filtration systems on indoor air quality. Indoor and outdoor concentrations of NO, NO2, TSP and PM10 were measured using automatic nitrogen oxide analysers and dust monitoring. Nitrogen oxides and particulate matter from traffic penetrated easily in the absence of filters.50%-70% of nitrogen oxides were excluded with chemical filtration. At holidays and weekends, the particle levels fell less than 10% of the outdoor level, rising to 25% on weekdays.

Describes a new method used to measure the amount of outdoor air supplied to individual building occupants, under field conditions. The method includes factors associated with office design. It is based on the measurement of the constant release of tracer gas into the outdoor air in the ventilation system. The obtained values are termed outdoor air supply indexes (OASIs). States that the type of diffuser, office, partition and return air inlet and their position relative to each other can have a considerable effect on the amount of outdoor air received at individual work stations.

Describes a study carried out in order to examine the relationships between the ventilation rate and the type of ventilation system on one hand, and objective nasal measures on the other. The method was to carry out a standardised investigation which included acoustic rhinometry and nasal lavage at a school. 279 persons at 12 primary schools in Sweden were invited and 84% participated.

The effect of exposure to different types of ventilation were examined using a cross-sectional study, which took into account indoor environmental measurements of major contaminants and aeroallergens. The study selected three buildings ventilated with heating, ventilating and air conditioning, fan coil units and natural ventilation. Questionnaire were answered by 1144 employees. Found that HVAC and FCU systems were related to a marginally higher risk of non-specific symptoms compared with natural ventilation.