AIR FILTER TECHNICAL SECTION - Technical Issues

SICK BUILDING SYNDROME - THE BASICS

Many papers have been dedicated to the discussion of Sick Building Syndrome over the years. They have covered such issues as trying to define what Sick Building Syndrome is or, in fact, if it even exists. They have tried to apportion costs that can be associated to this problem and ways of addressing and ultimately limiting the problems effects. All of this can take up an entire forests worth of trees, for which we have neither the time nor the need to discuss in this forum. Instead, we will look at the issue in its simplest form and at ways in which this can be addressed using well maintained Heating, Ventilation and Airconditioning (HVAC) systems and how the air filters are in the front line of the battle.  If you would like further information on this or any other topic regarding air filters, you can contact us either through our contact form, or via email: info@peregrineindustries.com.au

The term “sick building syndrome” (SBS) is used to describe situations in which occupants of large buildings experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified. In contrast, the term “building related illness” (BRI) is used when the symptoms of diagnosable illnesses are identified and can be directly attributed to the “indoor air quality” (IAQ) within the building.

In 1984 a World Health Organisation (WHO) report suggested that up to 30% of new and remodelled buildings worldwide may be the source of complaints about Sick Building Syndrome due to poor IAQ. This frequently is as a result of poorly maintained HVAC systems.

So what can be done about the IAQ in large buildings?

Four basic elements are required to maintain good IAQ in large buildings:

• Eliminate Tobacco Smoke

A smoke free work place has become commonplace in Australia in recent years. This has greatly reduced the problems of poor IAQ associated with tobacco smoke, but the problem still exists as many smokers will frequently congregate close to the HVAC air intakes for the building not to mention the cloud of tobacco smoke that is often associated with the entrances to many large buildings.

• Provide adequate “fresh air”

Guidelines for office buildings have been set out by ASHREA (see below). The recommend circulation of 15-60 CFM (7-28 l/s) per person of outside air depending on the activities that normally occur within the occupied space. This can be further assisted by the quality of the outside air being filtered through a well maintained air filter system within the HVAC which will in turn provide clean “fresh” air into the building.  Currently, most buildings in Australia use only up to an F5 rated air filter in their HVAC systems (many using untested air filters which may be as low as G2 rated), whereas in Europe F7 is commonplace and in America it is often higher again (for a description of test methods and filter ratings see Air Filter Ratings and Test Methods Around the World.

• Maintain the ventilation system

Regularly cleaning and disinfecting the HVAC ventilation system, with particular attention paid to maintaining all air filters and their housings. This includes regularly replacing the air filters as well as ensuring that no air bypass is occurring around the air filters and the framework that holds them in place.

• Remove sources of pollution

It is important to remove all sources of pollution that may be adverse to the IAQ. These include, but are not limited to, chemicals such as those that may be used in cleaning, furnishings and supplies that may release toxins such as formaldehydes, and equipment such as photocopiers that produce ozone (O 3, which is a known irritant to the human respiratory system), and electrostatic precipitators (electronic air cleaners that are used in some buildings to apparently increase the filtration efficiency, of course, if proper filtration is used in the first instance, then these systems have no place) which should not be used as they are generally ineffective and can also produce ozone.

Where these sources cannot be removed for practical reasons (such as in the case of the photocopier) adequate exhaust systems should be employed to remove the pollutants

Figure 16 – Ventilation recommendations (Source: National Coalition for Indoor Air Quality – USA)

As you can see from the above, it is necessary to pay very close attention to the HVAC filtration system in any building if adequate IAQ is to be achieved. Without regular maintenance, the HVAC air filtration system will become blocked. And when this happens, the rate of ventilation will drastically decrease and eventually air movement will become minimal. The quality of the filter will also impact on other equipment within the HVAC system such as the coils. If these coils become caked with dust, their efficiency will decrease, the resistance to airflow through them will increase and in extreme cases, they can also become a breeding ground for bacteria, fungi and other nasties.

National Air Quality Standards

Figure 17 - National air quality standards (source: Australian Government Department of Environment and Heritage)

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