SBS indicators resemble the symptoms of other types of diseases and were for a long time neglected by both employers and employees, who failed to notice the cause-and effect relationship between observed symptoms and the quality of interior environment.

Numerous epidemiological studies that have been conducted up to now have proved beyond any doubt that a considerable proportion of office workers often experience the above-described symptoms and that they disappear or subside considerably after leaving the building. It may be interesting to note that sick building syndrome is more frequent in women than in men, but the cause of this increased incidence of SBS in women has not been satisfactorily explained yet.

It is estimated that the sick building syndrome afflicts 20-30 percent of the entire workforce in offices. One-fifth or even one-fourth of all office workers in the world cannot work to their full potential, often falling ill and going on sick leave.

A building is defined as “sick” when 30 percent of all its users complain about its microclimate, suffering from the unpleasant symptoms mentioned above.

Statistical data indicate that sick building syndrome occurs in as many as 60 percent of office buildings w USA. Therefore, it is a serious cause for concern.

A long list of diseases

In Poland, sick building syndrome is generally reckoned to be a comparatively recent problem, which does not mean that Polish office workers had not experienced it before.

Forty or fifty years ago, nobody even suspected that chronic pharyngitis, recurrent rash, or malaise may be linked to indoor microclimate.

However, the last years have seen a rapid increase in the number of modern office buildings and public utility buildings in Poland, built with fast and light technologies. As the number of such buildings is increasing, so is the number of people suffering from SBS. The problem is most prevalent in office buildings, but it also occurs in supermarkets, cinema halls, conference rooms, and hotels.

Apart from sick building syndrome, which is the most common, the list of the World Health Organization additionally includes ‘Legionnaires’ disease (caused by Legionella bacteria breeding in ventilation ducts), humidifier fever, and neoplastic diseases caused by carcinogenic substances, such as cigarette smoke, asbestos, or radon.

All these diseases result from exposure to excessively polluted interior environment and are generally described as building related illnesses.

Fungi, moulds, and chemical toxins

Based on available data, it is possible to identify some of the most frequent causes of health complaints among office workers, such as:

• chemical factors (emission of harmful substances)
• radiation phenomena (including air ionisation caused by radioactive radiation)
• electrostatic phenomena (including voltage-induced ionisation of the air)
• biological factors (fungi, moulds and micro-organisms)
• insufficient air exchange rates
• exposure to vibrations and noise
• lifestyle-induced risk factors

The most crucial factors are biological factors, such as fungi and moulds. Some species of fungi, or to be more precise, products of their metabolism, i.e. mycotoxins, are ones of the most toxic natural poisons.

Old and improperly installed, and what is more important, infrequently cleaned ventilation, air-conditioning and heating equipment is a favourite breeding place of pathogenic microorganisms - bacteria and fungi.

Large amounts of toxic substances are also emitted by floor carpeting, carpets and their plastic components, furniture, adhesives, paints, varnishes, modern building materials and synthetic fabrics.

Whether the above-mentioned phenomena are significantly or only slightly harmful to health depends on their intensity, time of exposure and individual health predisposition of a given person.

Physical factors
The most important physical factors in interior environments are temperature and humidity. The optimal temperature is 21-22 degrees C and the optimal air humidity does not exceed 55-60 %.

Unfortunately, in “sick buildings” these values are significantly higher (about 24 degrees C and over 75%). Thermal comfort is to some extent an individual matter, but humidity of 70% makes the office feel “stuffy” and leads to headaches, irritations of mucous membranes, skin dehydration, and throat diseases. Occupants of such a building feel tired and distracted and find it difficult to breathe. Prolonged oxygen deficiency may have a very negative effect on their health.
Too high temperature and humidity may also contribute to the development of bacterial and fungal growth, in particular of the spores of mould fungi.

The main cause of bad physical conditions is insufficient room ventilation.

Too tightly sealed windows hinder natural microventilation, leading to the effect of “thermal tin”. In such a room, we feel as if we were in a warm, hermetic tin. Natural microventilation takes place in less tightly closed or intentionally draughty windows. It is essential for providing constant air exchange between the building and external environment (building ventilation standards call for 0.6 m3/min × person).

Inadequate air ventilation may also be caused by a faulty or badly designed ventilation system. Each ventilation system should be built in a way that ensures minimum air exchange rates in compliance with the applicable norms. Some designs of ventilation systems are based on the erroneous assumption that the only cause of air quality deterioration are body odours, not taking into account the contaminants produced by office appliances.

However, even the best-designed ventilation will be ineffective, if it is not maintained and cleaned properly. Unclean and not disinfected ventilation ducts not only stop to fulfil their function, but also pose a threat to human health.

Chemical factors

The composition of air, which we breathe, is significantly affected by substances emitted by different indoor materials. Office appliance and dust are another source of contaminants and suspensions in office rooms.

Construction and furnishing materials should belong to category M1. Materials of this category are subjected to tests to measure emission levels of harmful substances and to check their compliance with the applicable standards. M1 materials may produce insignificant amounts of harmful substances, which are easily removed by efficient ventilation systems and ventilation grates installed in the vicinity of office appliances.

Many buildings are constructed with cheaper materials belonging to category M2. They comply with permissible emission levels, but they may contribute to excessive air contamination, if the building is not equipped with a proper ventilation system.

Unfortunately, quite a large number of modern buildings are constructed with materials belonging to an even lower category - M3. These are the cheapest materials that contribute to high concentrations of harmful chemicals in the air inside buildings. They are not subjected to tests and may have particularly high emission levels.

How to protect oneself?

In a study published in the journal “The Lancet”, Canadian scientists demonstrate that sick building syndrome can be quite easily prevented by using ultraviolet lamps, which are usually used to disinfect operating theatres and patients’ rooms.

The ability of ultraviolet lighting systems to kill microbes has been known in medicine for decades. Of course, it is not a miracle remedy for sick building syndrome, because it does not eliminate all the symptoms that affect building users. It may be very helpful though, as ultraviolet lamps installed in ventilation ducts and their outlets can destroy over 90 percent of bacteria, fungi, and moulds breeding there.

The estimated cost of ultraviolet germicidal irradiation is about 52 dollars per worker for the installation and 14 dollars for yearly use.

To avoid the negative effect of SBS on human body, it is essential to use a proper ventilation design that is suitable for the type and function of a given building.

One of the criteria taken into account when designing a ventilation system is the ventilation rate, expressed by the amount of art transported or supplied to or removed from the room. There are many parameters describing the above-mentioned rate of ventilation, such as the amount of air supplied per one person in one hour [m3/h/person].

The amount of fresh air per one person was first established in 1858 by Max von Pettenkoffer, who set its limit at 32.5 [m3/h/person].

However, in 1936 it was reduced to 25 [m3/h/person]. It was further diminished in the 70’s of the 20th century during the energy crisis: to 9 [m3/h/person] in the USA and to 15 [m3/h/person] in the Scandinavian countries.

According to Polish standards, 20 [m3/h/person] of fresh air are required in non-smoking rooms and 30 [m3/h/person] in rooms where smoking is not prohibited. This limit may be lowered by 50% when external temperatures fall below -15°C and by 25% for temperatures exceeding +26°C.