Sick Building Syndrome
Public concern and awareness has grown over the last few decades about adverse health effects of exposure to chemicals in the everyday environment. Much research has focused on potential chemical exposure in the work environment in offices. In the 1970s reports linked symptoms to the occupancy of buildings that had been deliberately 'air-tightened' to conserve energy during a Middle East oil embargo. In the 1980s, the World Health Organisation (WHO) recognised the issue and described the situation of 'symptoms with increased frequency in buildings with indoor climate problems'. Symptoms included irritation of the eyes, nose and throat, dry mucus membranes, dry skin, headaches, frequent nasal symptoms, breathing difficulties, abnormal taste sensation. They also identified a distorted sense of smell, tiredness, dizziness, lack of concentration and nausea.
Sick-building syndrome (SBS) can be potentially diagnosed when regular symptoms can be linked to being in a particular building and problems are not experienced away from the building. This would be supported by the presence of colleagues within the same environment who are also experiencing such symptoms with the same temporal pattern. The diagnosis of SBS also requires the exclusion of symptoms arising due to allergies to mould and dust within the building. Also the presence of infection such as sinusitis, or outbreaks of more severe infection such as Legionnaire’s disease or tuberculosis. If skin problems predominate these could be caused by allergy, by contact sensitivity with certain office plants or by an irritant response to fibreglass. These possibilities need to be considered and excluded before reaching a diagnosis. SBS arises due to exposure to low levels contaminants within the air.
There is no single environmental factor or group of factors that have been established as a single cause of SBS. A list of common contaminants in indoor air is shown in Table I. Contaminants in ventilated buildings range from potentially fatal bacteria, such as for Legionnaires disease outbreaks, to more commonly volatile organic compounds omitted from pressed wood furniture. This may have been manufactured from MDF. Emissions from printers and photocopiers can also be a contaminant.
The adverse exposure to these factors is more likely if there is uneven or inadequate ventilation within the building environment. Ventilation is usually controlled by heating, ventilation and air-conditioning (HVAC) units. They draw air in from the outside, condition that air with respect to temperature and humidity, with the aid of the outgoing air, and then circulate that incoming air within the building. It is recommended that there is 20 cubic feet per mm (0.57 m3/min) of outside air per occupant of building ventilation. Whilst designs in new buildings should be correct, it is clear that ongoing changes could influence the ventilatory adequacy. For example, through environmental changes affecting the air intake, such as environmental pollution or loading bay exhaust, depending on the sighting of the intake vent, and changes within the building, such as the number of occupants or the internal structural and furniture arrangements. Overall ventilation may appear adequate. Yet, ventilation in different parts of the building may be uneven or, because of the internal layout, fresh air from the supply may be short circulated to return to the ducts. This may bypass the occupants breathing zone. Such local factors may account for symptoms only arising in selected individuals. It may be common in people resident for work in one environment, where they may have more prolonged exposure. But different for another individual who has responsibilities in several different areas and is not exposed for such a prolonged period to air in any one place within the building. Regional changes in air temperature, air humidity (e.g. too dry), lighting and air velocity may all be important determinants of SBS.
The individual’s response to the building air is also an important determinant of the expression of symptoms, in addition to the quality of the air. Studies have shown that SBS is more common in individuals with work related stress, poor job satisfaction and low job status. The diagnosis of SBS is based on the patient’s clinical presentation, the presence of similar symptoms in colleagues, improvement in symptoms away from the building and the absence of any other likely diagnosis. If such a diagnosis is considered probable, then there should be an indoor-air quality evaluation of the building. Remedial action for the building will depend upon this evaluation.
Common contaminants in indoor air
- Volatile organic compounds:
Formaldehyde, solvents, printed material, printer and photocopier emissions, paints and resins
Asbestos, man-made fibres (e.g. fibreglass), dirt, construction and paper dust
Bacteria, moulds, viruses, pollen, fungi, dust mites, animal dander and excreta
- Entrapped outdoor sources:
Vehicle exhaust and industrial exhaust
- Contaminants generated by human activity:
Carbon dioxide, perfume, deodorants and environmental tobacco smoke
- Physical factors:
Temperature, humidity, lighting and noise
Fuel combustion products, pesticides, cleaning agents and building materials
Author: Dr Peter Howarth, Southampton, UK - March 2006