What Is Sick Building Syndrome?

Sick building syndrome (SBS) is a situation in which occupants of a building experience acute health effects that seem to be linked to time spent in a building, but no specific illness or cause can be identified. The complaints may be localized in a particular room or zone, or may be widespread throughout the building.

This page looks at the symptoms and causes SBS. Air ionizers and Purifiers can be used to reduce or eliminate SBS.

What Are the Symptoms of SBS?

Building occupants complain of symptoms associated with acute discomfort. These symptoms include headaches; eye, nose, and throat irritation; a dry cough; dry or itchy skin; dizziness and nausea; difficulty in concentrating; fatigue; and sensitivity to odors. With SBS, no clinically defined disease or specific chemical or biological contaminant can be determined as the cause of the symptoms. Most of the complainants feel relief soon after leaving the building.

This page by the London Hazards Centre looks at the causes. Source: http://www.lhc.org.uk/

Causes of sick building syndrome

Despite numerous investigations, journal articles and conferences, little has actually been proven about the causes of sick building syndrome. Different experts have different theories - some say the main cause is chemicals, others that fungi are primarily to blame, or physical factors such as humidity, temperature or lighting, or the air-conditioning system itself.

In the USA, investigations carried out up to the end of 1983 by the National Institute for Occupational Safety and Health (NIOSH), a governmental organisation, showed 'inadequate ventilation' to be the causal factor in about half of buildings with health complaints (see Table 4). Inadequate ventilation was often given as the cause when no other, more precise, cause, could be found.

What is certain is that symptoms are more common in buildings with air-conditioning or mechanical ventilation. Six building features are strongly associated with symptoms of sick building syndrome (McIntyre and Sterling 1982):

• a hermetically sealed, airtight shell
• mechanical heating, ventilation and air-conditioning systems
• use of materials and equipment that give off a variety of irritating and sometimes toxic fumes and/or dust
• fluorescent lighting that may produce photochemical smog
• application of energy conservation measures
• lack of individual control over environmental conditions

The rest of this chapter looks in more detail at some of the effects of these features.

Table 4: Types of problem found in 203 indoor air quality investigations carried out by NIOSH

Source: Melius 1984

Airborne pollutants

Nearly everything we use sheds particles or gives off gases, particularly when new. People shed dead skin and hair all the time. Clothing, furnishings, curtains, carpets etc. contribute fumes, fibres and other fragments. Cleaning processes such as sweeping, vacuuming and dusting may remove the larger particles but often increase the levels of smaller, respirable, particles in the air. Chemicals used for cleaning are often toxic, and office supplies and equipment may also give off harmful chemicals.

Buildings are complex environments which can trap and concentrate pollutants as well as generate them. Outside pollutants find their way into buildings through air intakes and inadequate filtering systems. As long as ample ventilation ensures a constant supply of fresh air, indoor pollution problems may be kept to a minimum. But general ventilation is often inadequate and office equipment may have no local exhaust system venting fumes to the outside.

The A-Z list below contains some of the more common pollutants that may be found inside buildings and is compiled mainly from information supplied by the Queensland and Lidcombe Workers' Health Centres (1984) and the Northern Trade Union Health and Safety Centre (1989). It is not an exhaustive list of the many thousands of chemicals present in the environment.

When air monitoring for any of these substances is carried out, levels are likely to be below those considered to be 'acceptable' or 'safe'. However, little is known about the health effects of long-term exposure to low levels of a variety of chemicals and some people are sensitive to extremely low concentrations of toxic agents.

Ammonia

Cleaning solutions, blueprint machines (plan printers) and cigarette smoke are sources of ammonia. This gas irritates mucous membranes and so affects the respiratory system and eyes.

Asbestos

There are many sources of asbestos in buildings (e.g. pipe lagging, ceiling and roof tiles, asbestos cement sheeting) particularly in buildings constructed in the 1960s and early 1970s. In the air-conditioning system, asbestos may be used as duct insulation, as mounting for heating elements, or sprayed as insulation in the air-conditioning plant room. The inevitable deterioration of these asbestos products with time means that respirable fibres will be released into the air. Asbestos - blue, brown and white types - can cause cancer and fibrosis of the lung and mesothelioma (cancer of the lining of the chest and abdomen).

Benzene

This cancer-causing chemical is released from synthetic fibres and plastics, and is found in cleaning solutions and tobacco smoke. It damages the central nervous system and skin, and causes respiratory irritation.

Biocides

Biocides are added to air-conditioning systems to control the growth of micro-organisms. They are also toxic to humans; the effect depends on the biocide. Biocides and other chemical water treatments such as anti-scaling agents should not be used in humidifiers or in any part of the air-conditioning system where they may be picked up in the airstream and so breathed by workers.

Carbon dioxide

Carbon dioxide is present in the unpolluted atmosphere at a concentration of about 0.03 per cent but since about 5 per cent of the air we breathe out is carbon dioxide the level increases in inadequately ventilated occupied rooms. The level of carbon dioxide is therefore often used to assess the efficiency of ventilation, although NIOSH investigators did not find it useful for this purpose (Melius 1984). Levels higher than 800 parts per million (ppm) indicate that the ventilation rate is inadequate. Outside sources include vehicle exhaust fumes, nearby smoking chimneys or other exhausts.

The effects of too much carbon dioxide are headache and lethargy; then breathlessness, sweating, visual impairment and tremor. Finally unconsciousness develops as the level increases.

Carbon monoxide

Any process of combustion can produce carbon monoxide, so this gas is produced by tobacco smoking, gas cookers, and gas or oil heaters. We all exhale a small amount of carbon monoxide in our breath. A major source of carbon monoxide is vehicle exhaust fumes.

Carbon monoxide harms the body by replacing oxygen in the haemoglobin of red blood cells and so starving the body - and the brain in particular - of oxygen. Less than 1 per cent of the haemoglobin of non-smokers is normally bound to carbon monoxide rather than oxygen but this increases to 4-6 per cent in smokers (Hoover 1982). Non-smokers who spend their 8-hour working day in an atmosphere containing 30 parts per million (ppm) of carbon monoxide will also develop a 5 per cent concentration and possibly the early symptoms of carbon monoxide poisoning such as headache. Smokers would not be affected since their bodies have become habituated to such a high level. At levels of 50-250 ppm dizziness may accompany the headache, and above 500 ppm nausea and vomiting occur and collapse is possible. Long-term exposure to carbon monoxide is associated with heart disease.

It has been recommended that carbon monoxide levels be kept below 9 ppm in offices because of the potential for health effects associated with long-term exposure to low levels of this gas (Queensland and Lidcombe Workers' Health Centres 1984). In the UK the occupational exposure limit for carbon monoxide is 50 ppm.

Detergent dust

Detergent residues from carpet cleaning may cause respiratory irritation such as cough, dry throat, breathing difficulty, nasal congestion and headache. Effects depend on the type of detergent used and its formulation.

Ethanol (ethyl alcohol)

Ethanol is found in duplicating fluids and can cause dermatitis, liver damage and intoxication.

Fibreglass

Fibreglass is use for insulation. Large fibres can cause itching and skin irritation; smaller fibres are suspected of causing lung diseases and cancer in a manner similar to asbestos.

Formaldehyde

Formaldehyde is found in hundreds of different products, including insulation material, ceiling tiles, particle board, plywood, office furniture, carpet glues, various plastics, synthetic fibres in rugs, upholstery and other textiles, pesticides, paint and paper. It is also emitted from electric stencil-cutting machines and is present in tobacco smoke. Levels of emission increase with temperature.

Formaldehyde is a colourless gas with a pungent odour. At 2-3 parts per million (ppm) it will irritate the eyes, nose and throat of most people exposed to it, but many are affected at much lower levels. At 4-5 ppm the irritation is worse and is accompanied by drowsiness, loss of memory, sneezing and skin rashes. At 10-20 ppm there is severe breathing difficulty and burning eyes, nose and throat. Formaldehyde increases the risk of several types of cancer, and has also been shown to cause poor sleep, impaired memory, lack of concentration, nausea and menstrual irregularities.

The occupational exposure limit in the UK is 2 ppm, twice as high as the permissible level in the USA of 1 ppm, which has an action level of 0.5 ppm. In Sweden and Germany the maximum permissible indoor level is 0.1 ppm. People who have become sensitised to formaldehyde have adverse reactions whenever it is present, even in very small amounts. Concentrations as low as 0.01 ppm have been associated with eye irritation (HSE 1981)

Hydrocarbons

Chemicals composed of hydrogen and carbon are found in various sources including paints, solvents, synthetic materials, floor and furniture polishes, and vehicle exhaust fumes. Their effect on health depends on the type of hydrocarbon but can include respiratory, skin and eye irritation, nausea, headache, central and peripheral nervous system damage, and cancer.

Hydrogen chloride

Hydrogen chloride is emitted by electric stencil-cutting machines. It irritates the mucous membranes of eyes, nose and throat.

Methanol (methyl alcohol)

Methanol is used in spirit duplicating machines, and causes irritation to the eyes, respiratory system and skin.

Micro-organisms

Not much research has been carried out on indoor pollution with microbes such as bacteria and fungi (mould). In the USA, investigation of more than 200 governmental, hospital and commercial buildings showed that 34 per cent had high levels of fungi and 9 per cent had high levels of bacteria which could potentially cause disease or allergy (Robertson 1988). The fungal species Aspergillus and Cladosporium were found growing to excess in the ductwork of many of the buildings where workers had high levels of symptoms. In some cases, 'challenge' tests were carried out which showed that these workers had severe allergic reactions to the spores of these fungi. Subsequent cleaning and removal of the sources of contamination apparently cleared up the symptoms (Robertson 1988).

Micro-organisms are probably responsible for humidifier fever and extrinsic allergic alveolitis, which are discussed elsewhere, and for legionnaires' disease (see Chapter 3).

Motor vehicle exhaust

Exhaust fumes contain carbon monoxide, nitrogen oxides, lead particulates, sulphur oxides and hydrocarbons. Sources include basement car-parks which don't have their own separate ventilation system and outside traffic. The siting of ventilation intakes is therefore important in determining the intake of exhaust fumes into the building.

Nitrogen oxides

Like carbon monoxide, nitrogen oxides are produced as products of combustion, so sources include vehicle exhausts, tobacco smoke and gas heaters. These chemicals cause irritation to the respiratory system and eyes.

Ozone

Ozone is naturally present in the air since it is produced from oxygen by ultraviolet radiation. However, it can also be produced by electrical discharges and is emitted by some items of electrical equipment such as photocopiers and electrostatic precipitators (devices used to 'clean' the air by removing dust). A single photocopying machine can produce more than 0.1 parts per million (ppm), which is the recommended limit for exposure to ozone in the UK and Australia.

Ozone is a dangerous gas since it mimics the effects of ionising radiation (X-rays and gamma-rays) and can cause genetic damage. It is also very irritating to mucous membranes in eyes, nose and throat (at 0.1 ppm), causing lung damage at higher exposures. It can also cause headache (at 1 ppm), dizziness and severe fatigue. No one should work in the same room as a photocopier which is in constant use or employed for long runs, particularly if unvented.

Ozone is sometimes added to the air-conditioning system to 'sweeten' the air and counteract smells. This should never be done: an adequate supply of fresh air is what is needed.

Paint

Paint fumes, depending on the formulation, may cause headache and irritation to the eyes and respiratory system, damage to the nervous and reproductive systems, and kidney and bone marrow injury at high exposure levels.

PCBs (polychlorinated biphenyls)

Use of these dangerous chemicals, which include dioxin and dibenzofuran, is now banned in the UK, but they may still be found in electrical appliances and may leak from ageing visual display units and fluorescent lights. PCBs cause skin rashes, cancer, foetal defects, and damage to reproductive organs, liver and kidney.

Pesticides

Pesticides may be used inside buildings for many reasons: to kill fungi, beetles, fleas, ants, booklice, silverfish, rodents, and plant and timber pests. Although all pesticides are harmful to humans (some more than others), treatment is sometimes carried out during working hours, with little apparent concern for the health of the people working at their desks. Or spraying may be carried out overnight or over the weekend so that the chemical is still circulating in the atmosphere when workers return to the building. The pesticides used as wood preservatives often leach out into the air over a number of years.

Pesticides may be added to air-conditioning and ventilation systems to reduce biological contamination. This is not the way to effect control: proper cleaning and maintenance are what is needed, or the chemicals will be circulated around the building.

The hazards of pesticides depend on their chemical constituents (often a 'cocktail' of chemicals is used) and include cancer, foetal damage, liver and neurological damage, skin problems, and irritation to the eyes and respiratory system.

Photochemical smog

It is possible that the various individual pollutants may combine to form new hazards, and it has been suggested that ultraviolet light from fluorescent tubes provides energy for reactions to occur between ozone and other chemicals.

Radon

Radon is a decay product of uranium and is present in varying amounts in the soil. It moves from the soil by diffusion into the soil's air pockets and into soil water, from where it can migrate through building foundation cracks etc. into the indoor space. Building materials such as concrete and stone may also contain radon. Out-gassing from these materials, and from radon in the water supply, adds to the indoor air levels derived primarily from the soil below the building.

The effects of high levels of radon on humans are those associated with ionising radiation (X-rays and gamma-rays): cancer and damage to the reproductive organs and to the fetus. The effects of low levels of exposure are not known but the Institution of Environmental Health Officers recently recommended a 50 per cent reduction in the levels considered to be 'safe' for homes in the UK.

Solvents

Solvents such as toluene, acetone and trichloroethane are found in white-out fluids and thinners. They may cause headaches and dizziness or eye, throat and skin irritation. Solvents are also found in adhesives, glues, cleaning fluids, paint and felt-tip pens. Trichloroethylene, which can cause liver cancer and damage to be lungs and central nervous system, is used in spray adhesives and some types of stencil machine.

Sterilant gases

Gases such as ethylene oxide are sometimes used in an attempt to sterilise humidification and air-conditioning systems. The effects will depend on the gas used, and may range from irritation of mucous membranes to cancer. Such gases should not be used.

Sulphur oxides

Sulphur oxides, such as sulphur dioxide which is emitted from coal-burning power stations, chimneys and vehicle exhausts, form acidic solutions when in contact with moisture.

Exposure to sulphur dioxide causes respiratory irritation, runny nose and cough. Long-term exposure can lead to chronic bronchitis, lung damage, altered sense of smell and may act in the presence of other chemicals to produce a cancer-causing effect (co-carcinogenesis).

Tobacco smoke

Cigarette smoking is a considerable source of airborne contamination. Amongst other things, tobacco smoke contains carbon monoxide, carbon dioxide, nicotine, formaldehyde, acetaldehyde, acrolein (a strong irritant), ammonia, hydrogen cyanide, nitrogen oxides, coal tars and particulates. Many of these substances have toxic or irritant properties causing symptoms similar to those of sick building syndrome - eye and nose irritation, coughing, breathing difficulties, sore throat and hoarseness, headache, nausea and dizziness - in both smokers and non-smokers. The long-term effects of smoking include lung cancer and heart disease.

Vinyl chloride

Vinyl chloride is found in plastic products such as pipes and light fixtures and in upholstery and carpets. It is a cancer-causing agent and causes skin and lung irritation.

Air-conditioning systems

Air-conditioning is the process of treating air to control its temperature, moisture content (humidity), purity and distribution. Early proponents of air-conditioning believed that they could produce an atmosphere like a 'perpetual spring'. In practice, the air is often not so sweet.

In buildings with no air-conditioning, fresh air enters by natural ventilation or infiltration - through open windows and doors and gaps in window and door frames. Outside wind pressure makes the air circulate inside, and air also rises as it is warmed. In contrast, the windows of buildings with air-conditioning often cannot be opened because the system is so designed that its controls may be 'thrown out' by even one opened window. These buildings are 'sealed' or 'tight'. Air-conditioning systems rely on mechanical ventilation for air distribution.

There are many different types of air-conditioning and ventilation system. The simplest, which is described as 'mechanical ventilation', only filters and distributes ducted air; the air is not 'conditioned' by heating, cooling or humidity control. Table 5 gives an idea of the range of air-conditioning systems. Not all offices have systems with a plant room and ductwork. Some use domestic-style wall units which take in air through the outside wall, condition it and deliver it straight to the office space.

Despite the wide variety of types of system, they all work along similar basic principles (see Figure 00): an air handling unit draws air into the plant (or unit) where it is treated (filtered, cooled, heated, and perhaps humidified or washed) and then blown through ductwork, entering the office space through supply air vents.

In all-air systems, all plant is centralised and the conditioned air is distributed throughout the building by a network of ducts. These systems are inflexible and the ducting for supply and return air is bulky. The other extreme is the local air handling system. Each room may have its own induction or fan-coil unit, perhaps with a fresh air intake through the wall. These systems are more flexible, often with individual controls in each room. In between comes the decentralised system, which is similar to the local system except that a whole zone (a group of rooms, a wing or a floor of a building) is served by one air handling unit.

In practice, the humidification part of the process may not be in operation to save money on energy costs. Ask for a plan of the air-conditioning system or systems operating in your workplace. Trade union safety representatives are entitled to this information under the Safety Representatives and Safety Committees Regulations (see Appendix 5).

Table 5: Air-conditioning systems

Source: Croome-Gale and Roberts 1975

Outside air inlets

The supply air fan draws fresh air into the building through the outside air inlets. The siting of this intake may be critical in determining how 'fresh' the air actually is. City air can hardly be called fresh, but it may be additionally polluted if the inlet is located in the basement car-park, at pavement level along a busy main road or next to a flowerbed (where pesticides may be sprayed), downwind of a hospital incinerator or chemical plant, or next to a cooling tower or exhaust on the roof. The positioning of fresh air inlets must take into account prevailing wind directions and wind patterns caused by nearby buildings. Inlets should be louvred or wired to prevent birds, large insects and wind-blown debris from entering, and should slope so that rainwater drains away and does not enter the mixing chamber.

Mixing chamber

Here the outside air is mixed with return air from the building. It is usually intended that 10-20 per cent of the air mixture is fresh, but the fresh air dampers may be closed completely so that 100 per cent recycled air is being circulated.

In the USA, ACVA, a commercial organisation that specialises in sick buildings, found that over 35 per cent of 223 buildings it investigated were taking in no fresh air and 64 per cent had inadequate fresh air intake (Robertson 1988).

Filters

Filters are supposed to remove dust and other impurities from the air but are often inefficient or so poorly maintained that they actually pollute the air. In many air-conditioning systems the filters are designed only to stop large insects such as moths and butterflies. There are several different types of filter which vary in their efficiency.

A good filter system will have more than one filter, perhaps including a coarse pre-filter, and the selection will be based on:

• anticipated dust load
• type of dust (e.g. soot, ashes, earth, sand, fibres, animal, vegetable and mineral matter, mould spores, bacteria, viruses, pollen, industrial pollutants)
• size of dust particles (larger particles settle out on desks etc., smaller particles remain airborne or 'stick' to other surfaces due to electrostatic attraction)
• degree of cleanliness required

Filters in common use are dry filters, wet filters and electrostatic filters:

• Dry filters are usually disposable and made from a fabric or paper-type material which can trap larger dust particles in the airstream. There are two types: the roller type works like a film in a camera, automatically moving on to the next 'frame' when loaded with dirt. The panel type needs to be cleaned and reused or discarded once soiled.
• Wet filters are relatively coarse filters made from fibres, wire mesh, metal turnings or plates and coated with a viscous substance such as oil or grease. Again, there is a self-cleaning roller type and a fixed panel type. They are often washable and reusable.
• Electrostatic filters are much more efficient than wet or dry filters for both large and small particles. They work by passing the air through an ioniser which gives particles a positive or negative charge. These charged particles then go through a collector where they are attracted to plates of the opposite charge. Older models of electrostatic filter may produce ozone, as may newer models if they are left in operation with no airstream passing through them. (In one office building, workers received a 'blast' of ozone each morning when the air-conditioning system was turned on in the morning because the electrostatic filter had not also been switched off overnight.)

Filters will not work if they are clogged up with dirt: they must be regularly maintained, cleaned or replaced. Only electrostatic and HEPA (high efficiency particulate air) filters will remove bacteria. Beware of HEPA filters that contain asbestos; these should not be used.

Cooling and biological contamination

As well as removing heat, the cooling coil incidentally dehumidifies the air: moisture in the warm air is condensed out on the cold coil and drops collect in a drip tray. Wherever there is water, particularly if it is left standing for a long time, micro-organisms will grow. And wherever micro-organisms will grow, the potential for humidifier fever and extrinsic allergic alveolitis exists. Despite its name, humidifiers are not the only source of the organic dust believed to be the cause of humidifier fever - any dirty, dusty, damp place such as drip trays, ductwork, evaporative cooling systems, spray cooling devices (air washers) and baffle plates may be a source. These parts of the air-conditioning system are also those where the legionnaires' disease bacterium may grow, and more details on biological contamination are given in Chapter 3 (pages 00-00). [Please give the air-conditioning equipment pages of legionnaires' chapter]

Control systems

There are as many different systems to control the temperature, humidity and delivery rate of the air as there are air-conditioning systems - each building will be unique, and some computer-controlled systems are very complex. The siting and number of thermostats, humidistats and other sensors is crucial to the functioning of the system.

In a variable air volume (VAV) system, when the temperature of the office deviates from the 'set' temperature (perhaps because more people are present) the thermostat automatically controls baffles in the ducting to allow more or less air into the space to maintain the set temperature. Thermostats need to be re-set monthly depending on the average monthly temperature outside since people's bodies acclimatise to different temperatures in different seasons and they dress for the weather.

Temperature problems in buildings may result from:

• Wrongly placed thermostats. Sometimes thermostats are locate