It is probably true that people are the major contributors to indoor pollution. We exhale carbon dioxide, we perspire, we shed skin scales in their millions with each skin scale reputedly carrying around four living organisms and we involve ourselves in a whole range of activities such as wearing cosmetics, using hair sprays, aftershave lotions, deodorants, etc. We also use cleaning substances, detergents, polishes, paints, varnishes and generally create a "soup" of volatile organic chemicals. To these we can add chemicals and particulates from the building itself or from the furnishings. These include formaldehyde used in adhesive compounds and resins, radon from the sub-soil, plaster dusts, synthetic and natural mineral fibres including asbestos, glass wool and ceramics. On top of this we cook, smoke and use various types of heating appliances, many of which add to the internal pollution complex. This seemingly endless number of airborne contaminants we generate, some of which are known or suspected of being carcinogenic, include many that are simply irritants and others whose effect on human health has yet to be positively determined. As building occupants we are also confronted with a vast array of living and dead airborne microbial matter including bacteria, fungi and protozoans.

Finally we are affronted with pollution introduced to the indoor environment from outdoors. This includes motor vehicle and factory emissions, dust particles, pollens, etc. so it is not surprising that the allergy clinics are full and people are increasingly complaining about poor conditions indoors. In the USA the Environmental Protection Authority (EPA) measured indoor pollution up to 100 greater than outdoors.

The media of course is full of stories of people who believe their health has in some way been compromised by indoor contaminants but how much of this can in fact be substantiated and what should be done about the problem?

Healthy Buildings International has now examined some 2,000 major buildings around the world with an estimated two million occupants. As arguably the world's most experienced indoor air quality consultants we believe firmly in the concept of clearly identifying a problem before attempting to arrive at a solution. We also believe that the correct solution should be applied to the right problem if lasting benefits are to be gained. If we attempt to apply the wrong solution to the right problem or the right solution to the wrong problem we will forever be wasting time and money on a fruitless cause.

Identifying the Problem

Building Related Illnesses

Sick Building Syndrome

Solutions

By contrast the problem of sick building syndrome is more appropriately addressed using what we call a "building systems approach". Proper design and operating procedures coupled with effective maintenance readily allow engineers to address exposure to (for example) carbon monoxide, ozone ammonia, formaldehyde, benzene, nitrous oxides, polycyclic aromatic hydrocarbons, environmental tobacco smoke (ETS), bio-aerosols, pollens, dusts, volatile organic compounds, radon and a whole range of other indoor airborne contaminants.

Even though some of these substances are known or suspected human carcinogens their presence in buildings is invariably found at levels close to or below the lower limits of scientific detection. They are also invariably present in the ambient air so it seems pointless embarking on witch hunts to try to eliminate from buildings all known sources of these substances when it is impossible to eradicate them all.

It is appropriate therefore that scientists develop (and continue to assess) permissible exposure levels (PELs) for these substances and that engineers design and operate buildings in a manner that ensures these PELs are not exceeded. This is best achieved, in our view, by using ventilation and filtration standards adequate for the task.

Ventilation

Filtration

HBI experience shows this is seldom done. In fact the filters in 40% of the buildings studied by HBI do not meet ASHRAE's recommendation of at least 35% efficiency (to ASHRAE 52 Dust Spot test). The Europeans meantime are moving to a 50% equivalent minimum standard (EU5, DIN 24185).

All HVAC systems get dirty over time and many systems are severely compromised by emissions found in the ambient air. Nearby building construction and demolition work may compromise air quality. Bus, train and taxi pick-up points are areas which tend to have high levels of ambient pollution and of course chemical factories and manufacturing plants may compromise air quality, so care needs to be taken to minimise these problems at the design stage when locating the outside air intake ducts. A study by the Melbourne University department of building and architecture looked at some 300 buildings in Melbourne and found more than half (54%) of the outside air intakes on these buildings were compromised by emissions from the building itself.

Even if the outside air intakes are located correctly, they may still be compromised by dust and smoke from occasional bush fires, chemical fires and dust storms. Yet few if any of these intakes have any inbuilt mechanism to alert building managers to temporarily close down the ventilation in the above instances, or to automatically re-open them when the temporary threat has ceased.

The nett result is that even if there is an effective filtration system, it may rapidly become overloaded and many systems simply collapse, releasing the contents into the air supply, sometimes with devastating results.

System Hygiene

In our studies of buildings we note that many areas of the HVAC system are impossible to access for inspection let alone for cleaning, a situation also observed by the Melbourne University studies. Those areas capable of inspection and maintenance are often neglected through either ignorance, apathy or simply a lack of budgeted funds. As a consequence dirt accumulates sometimes in vast quantities and always detrimental to the health of the occupants.

Conclusions

Smart property owners embrace "pro-active monitoring" programmes to address indoor air quality problems.