People working in some old buildings develop allergic-like symptoms (sneezing, runny nose, and itchy eyes) or ‘sick building’ symptoms (one or more of the following temporally related to work: headache, fatigue, stuffy nose, irritated eyes, dry facial skin or sore throat). These symptoms disappear when the worker is away on holidays and also over long weekends. The symptoms recur when the people return to the building for their regular work. Many studies show that the prevalence of most symptoms associated with the sick building syndrome decrease by 40% to 50% after the workers move to a building with an improved ventilation system.
Bioaerosol (specifically airborne fungus e.g. Alternaria allergens and house dust mite allergens) concentrations in office environments are responsible for the allergy and the sick building syndrome. The presence of airborne Alternaria allergen at work sites was significantly associated with poor ventilation system and this was in turn associated with lower efficiency of the filters. In Malaysia the ducts associated with the central cooling system is loaded with fungal and bacterial growth and is most likely the cause of sick building syndrome.
The ducts are rarely cleaned and the accumulated fungal and other growth can be substantial in these ducts in an old building. Many people with true allergy may suffer from exposure to the fungal spores or dust mites in offices located in the tropics. The high concentration of fungal material present in old buildings may also aggravate true allergies in people working such buildings.