The latest news on sick buildings

Firstly, people who consider that they suffer from living or working in a 'sick building' need to ask themselves a few simple questions to try to ensure that this is what they suffer from. It is reasonably well accepted that if it is a particular building that is causing the problem then the patient should feel better when spending periods of time away from that building e.g. at weekends or when taking holidays if it is your place of work.

• If symptoms ease then you can be fairly sure it is the building, or something within the building that is causing the problem.
• If symptoms do not ease then there may be some other cause which is not confined to the building.

Symptoms associated with sick building syndrome are, in order of commonest first*:

• Irritation of the eyes
• Cough, hoarseness, sore throat
• Fatigue (tiredness)
• Rhinitis (runny nose)
• Nasal congestion
• Dyspnoea (breathlessness)
• Irritation of the skin, headache
• Nausea, dry throat, chest pain, exacerbated psoriasis
• Sinusitis (inflammation of the sinuses), otitis (inflammation of the ear)
• Arthralgia (pain in joints without swelling), dizziness.

For the most part, research concentrates on the supposition that people get sick from being in a building because they are breathing in substances that effect their health.
There are two possible health problems I can think of that occupying a sick building could cause:

• Allergic response to airborne particles - usually dust, fungal/bacterial spores etc.
• Illness caused by toxins released into the air - these could be man-made e.g. odourless chemical fumes., or they could be microbial toxins.

Most of the research that relates to micro-organisms such as Aspergillus ( the focus of this website) concentrates on the situations where it is obvious that there has been extensive growth of micro-organisms within the building - most obviously when there has been water damage either due to slow seepage or flooding. Once damp a lot of building materials will rapidly become infested with fungi and bacteria.
If there has been a single 'one-off' flood then it is possible to clean up the building by removal of all contaminated materials. On the other hand if there is unexplained dampness eminating from an unknown source, the chances are that cleaning up the contaminated materials will help the problem only for a short time - as the dampness is still present so the moulds will re-grow.

Usually (e.g. following a flood), the micro-organisms grow rapidly over a few days until the moisture starts to dry out, and then will start to form spores - effectively tiny 'seeds' which are blown through the air with very little effort for very long distances. If dampness is long term and persists then the micro-organisms will steadily release spores all of the time.
Spores stay suspended in the air for very long periods of time - the air outside is full of spores almost all the time. The number of spores in the air depends on several factors, notably dampness of the environment (see information on spore concentration in the air throughout the USA - you may be surprised at how high spore counts can get in some places!).
Within a building the number of spores in the air can be measured from 10-50 spores per cubic metre (low), a few hundred (medium) up to 1000 or more (high).

Allergy
People consistently exposed to high spore levels are likely to begin developing allergic sensitivity to spores and to other allergans. If they are already asthmatic the chances are high that they will start to react to too many spores in the air quite quickly. Such allergic reactions are well recognised by the medical profession and there are effective treatments to supress the symptoms - but it must be said that it would be preferable to have cleaner air to breathe in the first place! No employer or landlord should compel its employees or tenants to have to take quite heavy duty medications like corticosteroids to cope with a mouldy atmosphere.
There is a good article on house dust-related allergies in the book 'Health implications of fungi in indoor environments'***, pages 3-7 of the chapter entitled 'Health implications of fungi in indoor environments - an overview'.
There have been several large, well conducted studies including several thousand children in USA and Europe that have shown a good correlation between those that live in damp, mouldy houses and increased respiratory symptoms and some non-respiratory symptoms - strikingly, in one study the size of the effect recorded was similar to the size of the effect caused by a child living with a parent that smokes cigarettes.

Microbial toxins
It is well documented that many microbes produce toxins, many of which are very poisonous. It is also now well recorded that the types of microbe that infect buildings do produce toxins when growing on the building materials - one research group that has done a lot of work on this is the Research Unit of Ecotoxicology and Ecobiotechnology at the University of Helsinki, Finland**.
This group has developed laboratory tests which are sensitive enough to detect the poisons purified from contaminated building materials.
One of these tests uses cells which are part of the immune system, and detects that one of the poisons purified from building materials (Valinomycin) kills these cells. This means that if this happened to a person, then that person would be more susceptible to infections. It must be emphasised that this experiment was only carried out on isolated cells outside of the human body so it cannot be taken as proof that this will happen to a person in a sick building.
This group have gone further and have been able to measure the amount of Valinomycin found in dusts gathered from the air in some buildings. They have been able to do a rough calculation which suggests that dust can contain enough Valinomycin to have a toxic effect when breathed in over several days.
As far as I know this is the first time this has been shown and is encouraging for people who believe that they suffer toxic effects from the air they breathe in.

This group have been unable to find toxin in housedust from Aspergillus (or any other fungus) species in quantities sufficient to do any harm - Valinomycin is produced by a bacterium (Streptomyces griseus) which they found living closely associated with the fungus Stachybotrys.

Aspergillus species do produce very potent toxins known as aflatoxins (see pages 7-28 of 'Health Implications of Fungi in Indoor Environments***'), but most work on health hazards caused by this toxin when breathed in have been limited to groups of workers who breathe high levels of contaminated dust as part of their occupations e.g. Danish corn and peanut processing workers. This toxin has been demonstrated to reduce the efficiency of the immune system of laboratory rats, but as mentioned before there is as yet no evidence that house dust can contain enough of this toxin to have this or any other toxic effect on the health of the house occupants.
NB This is not the same as saying that this could not happen in a heavily contaminated building under the right conditions, all it means is that no example has yet been found.

Many other microbes grow in damp buildings - I have already mentioned Stachybotrys - there have been examples recorded of people working in an infected building who suffered symptoms consistent with inhaling Stachybotrys toxin.
NB This is not the same as saying Stachybotrys toxin caused those symptoms - as we know there are many other potential microbial and other offenders.

So, as far as mycotoxins go we know the following to be true:

• Several microbes which can grow in damp buildings can potentially make toxins under those conditions.
• The toxins can cause reduction in efficiency of the immune system of animals, and can cause neurological problems.
• The toxins can be carried on spores and other dust floating in the air.
• A'sick building' can contain higher levels of spores and other dust floating in the air compared with the outside air or with a 'clean' building.
• People who breathe in very large quantities of dust (i.e. because they do very dusty work) contaminated with mycotoxins suffer from higher risk of developing liver and biliary cancer.

The problems of making conclusions with regard mycotoxins and people living in mouldy houses are that to my knowledge no research has yet showed that people who are sick from living or working in a 'sick building' have :

• Any mycotoxin in their bodies (wherever it came from)
• Any reduction in immune system function
• Any demonstration that mycotoxin can lower immune efficiency (or have any other effect) in humans at all!

Work continues on these fronts and it is probably true to say that more is being done now than in the past as 'sick buildings' receive more attention.

Volatiles
As anyone who has visited a damp building knows, many micro-organisms (including the fungi) can produce unpleasant smells. Whether a smell is produced can depend on what the micro-organism is growing.

Toxicity of the chemicals that cause these odours is low, but they have been suggested to be irritant and therefore capable of causing nasal irritaion and congestion***.

Summing up
There is little arguement that 'sick buildings' exist. Symptoms claimed by occupants of such buildings are well documented and consistant. The only issue left to solve is what is causing the problem.

I have not discussed other factors that can help make a building unpleasant e.g. poor flourescent lighting, poorly adjusted computer displays, photocopier ozone etc., but these could all have a role.

It is becoming clearer that microbial growth can have detrimental effects if breathed in high enough quantity, but how much is required for a particular health problem to start may depend on so many factors, it has been extremely difficult to pin down general rules to work with.

Despite the lack of specific evidence available in my opinion it is reasonably safe to conclude that if you live or work in an obviously mouldy building and are suffering from many of the symptoms listed above, and if these symptoms drop in intensity when you are not occupying the sick building for a week or so and come back when you have started occupying it again, then you should not be in that building!
It doesn't really matter what is causing the problem specifically, for you the building is not good!

My speculation: Allergic effects may take months or years to develop & require much lower levels of contamination than is required to trigger toxic effects. Different organisms may grow well in some building but not in others and so on.
' Sick buildings' are therefore likely to be a catch-all expression for a wide variety of health problems caused by a lot of different agents - in micro-organisms alone there are at least a dozen possible candidates for making people unwell.
The aim of research is to pin down one or two of these where all the evidence is clear cut and there is direct proof that a particular organism is having a particular effect for particular reasons. Several groups are edging towards this situation for toxicity and allergy - it is probably true to say allergies are more accepted as being caused by high concentrations of spores in a sick building than toxicity problems.

References
*from 'Bioaerosols, Fungi and Mycotoxins: Health effects, Assessment, Prevention and Control'., edited by Eckhart Johanning MD, MSc., published by Eastern New York Occupational and Environmental Health Center, Albany, New York, USA, 1999.

** Prof. Mirja Salkinoja-Salonen & Prof. Kaarina Sivonen, Dept of Applied Chemistry & Microbiology.

*** 'Health Implications of Fungi in Indoor Environments' eds. RA Samson, B Flannigan, ME Flannigan, AP Verhoff, OCG Adan & ES Hoekstra., published by Elsevier Science BV, Amsterdam, The Netherlands, 1994. ISBN 0-444-81997-5.

Graham Atherton 11th Dec 2000