The NHS states that research on the cause of SBS has been ongoing since the 1970s, but no single cause has been identified.

The cause of SBS is usually directed to several factors that work in combination and build up to a point at which people within the area start to be physically affected. The main cause of SBS is believed to be related to the quality and effectiveness of the internal ventilation system. The main contributors to SBS include the following.

Inadequate ventilation/poor indoor air quality

Poor ventilation rates and ineffective circulation of air is held as the main cause of SBS. Air conditioning units and the pollution within the atmosphere from both inside and outside the building are believed to be the main contributors. This pollution is then circulated around the build, which has a negative effect on the Indoor Air Quality (IAQ), because of high numbers of air contaminants such as gases like CO, CO 2 , VOCs and particulates.

Motivating this theory is the fact that when ‘energy efficient’ offices were constructed from 1973 onwards, the amount of outdoor ventilation per individual occupant was set at five cubic feet per minute (cfm). This amount was considered in many cases to be highly inadequate for maintaining a healthy and comfortable working environment. It was not until the mid-1990s that the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) revised the amount per occupant to 15 cfm, this being raised to 20 cfm for offices and up to 60 cfm (minimum) for areas of specific use where heavy pollution may accumulate, or is produced (Bialous and Glantz, 2002).

This additional ventilation rate may help to reduce the number of complaints regarding indoor air quality, and this has not yet been proven, although the Chartered Institution of Building Services Engineers states that

… SBS is not linked to the type of ventilation or air conditioning system used but is more likely to be a function of how well systems are installed, managed and operated … Workspaces conforming to CIBSE guidelines on temperature and air movement should not suffer SBS, unless there are aggravating work related factors or extreme levels of pollution. (Armstrong, 2001)

Volatile organic compounds (VOCs)

VOCs are carbon-based (organic) compounds that have a high vapour and low water solubility, and therefore evaporate at ambient temperatures within a building. These compounds come from a range of indoor sources such as photocopiers, printers and cleaning supplies.

VOCs cause damage to the human body in a variety of ways, ranging from headaches and fatigue to shortness of breath, when exposed to significant levels.

Experts estimate that the VOC levels of indoor air sometimes reach 100 times those of outside air (All Business, 1990).

Internal sources of pollution

Internal sources of pollution mainly consist of the synthetic materials within furnishings and the fabric of the building that may release volatile organic contaminants (VOCs). The use of mechanical devices such as computers and fax/copy machines can give off emissions and heat that can increase the contamination levels within (Figure 3).

Figure 3 A section of drywall in disrepair. This breakdown of building fabric can result in Volitile Organic Compounds (VOCs) being released within the internal atmosphere. Full size image

Poor maintenance and inappropriate cleaning methods can release chemicals from cleaning agents into the environment, further compounding the situation.

External sources of pollution

External emissions such as car exhaust fumes and other industrial pollutants add to the poor indoor air quality, as they gain entry via intended and non-intended openings within the building fabric (Figure 4).

Figure 4 Close proximity car parking. External pollutants from vehicles and inner city factories contribute to the internal environment via intended openings such as windows or, as in this case, unintended openings such as those created by disrepair of the building envelope. Full size image

Although buildings are initially designed to be airtight, non-intended openings, either from poor design/construction or from disrepair over the years, or intended openings in the building envelope such as windows, allow pollution from outside the building to enter, collect and then circulate around the occupants (Figure 5).

Figure 5 Vegetation entering the building via window sills. This plant life shows, and may possibly be the cause of, a breakdown of the building fabic, resulting in external pollutants being allowed to enter and contaminate the internal atmosphere. Full size image

Temperature and humidity

An environment that is either too hot or too cold causes a physical reaction for occupants. This response can have a greater effect on staff who may be more susceptible to either extreme temperature, further adding to distress on the human body.

Dry, airless conditions are common within sealed buildings, the result of this being coughing, a sore throat and, in some cases, increased risk of dehydration, thus leading to both physical and mental negative effects.

Noise

Noise levels within the building can add further stress to occupants, whether the noise is of a low or high level, constant or intermittent, and so on. In offices, it is common for low-level background noise and the high-pitched ringing of telephones to be present; this noise pollution is widespread in offices that have ‘open plan’ layouts.

Poor or inadequate lighting

A significant lack of natural daylight or mechanical lighting that is flickering, too bright, too dull and/or does not emit the right type of light for the surrounding working conditions can cause discomfort to users in the immediate vicinity.

Psychological factors

Job factors such as stress and anxiety resulting from the working position, especially when computers are used at a workstation for long periods of time, and pressures of meeting work criteria can also contribute to the causes of SBS (Compiled from The Environmental Illness Resource The Environmental Illness Resource (EIR), 2007).

Indoor air quality investigations

Investigations carried out by the National Institute for Occupational Safety and Health (NIOSH) into the air quality of buildings with air conditioning equipment show what problems are found in enclosed buildings (Figure 6; London Hazards Centre, 1984).

Figure 6 Types of problems found in 2003 Indoor Air Quality (IAQ) investigations. Source: The National Institute for Occupational Safety and Health (NIOSH) 1984. Full size image

The investigations conducted show that the greatest problem by far comes from the air circulation and quality in and around the building; these are factors that can be controlled and managed by the employer with adequate management plans.