This Office Makes Me Sick!

Indoor air pollutants are associated with or directly related to numerous health-related symptoms or complaints. Some of these have been traced to biological contaminants, which can include the organism itself (as simple in structure as bacteria or as complex as a cat) or materials that the organism sheds, eliminates, or produces, such as fungi, bacteria, viruses, and insect parts and feces.

The most effective means of avoiding fungal growth is to keep the water out by monitoring for and avoiding the following:

• High humidity levels
• Water leaks
• Moisture migration through masonry walls
• Condensation

Each of these conditions can have several causes. For example, high humidity levels can be due to certain activities taking place in the building, such as operating a chilled water air conditioning system at too high a temperature. A comprehensive evaluation may be needed to determine the actual source of a water infiltration problem.

Following these rules of thumb can help you manage water infiltration:

• If growth has occurred on a hard surface, the surface can easily be cleaned. However, if growth has occurred on a porous surface such as plasterboard, carpet, ceiling tile, the porous material should be carefully removed to prevent the uncontrolled release of a cloud of spores into the building's environment.
• To avoid fungal growth in porous materials where water infiltration has occurred, the material must be dried within 24 hours.
• Fungal-contaminated materials should be removed under controlled conditions. Airborne fungal levels can increase by a factor of 10 or more when fungal-contaminated materials are removed or disturbed. 'Controlled conditions' means that steps are taken to prevent the spread of fungal contamination to clean areas and to protect building occupants and the abatement area from elevated fungal exposures.

Even though work related to the removal of fungal-contaminated materials isn't regulated, the Occupational Safety and Health Administration and some state health departments are becoming concerned about the exposure of fungus abatement workers and building occupants to fungal spores and other compounds. Therefore, if fungal contamination is present, an appropriate response is needed not only to protect the health of workers and building occupants, but also to avoid negative scrutiny by regulators.

Bacteria growing in mechanical cooling towers of buildings is the source of considerable contamination. Exposure to bacteria-filled mist can cause various diseases, especially among individuals with compromised immune systems. (One famous case involved the bacteria Legionellosis, the so-called Legionnaire's Disease.) Placing cooling towers away from outside air intakes, continuous chemical treatment of the water, and high-efficiency drift eliminators will reduce this hazard.

Another potential illness is humidifier fever, which is caused by an adverse reaction to chemicals in the bacteria. Decorative fountains with inadequate chemical treatment or room humidifiers that aren't appropriately cleaned are often the culprits. Unfiltered humidifiers that produce a cool mist are significant bacteria reservoirs; they should be replaced with evaporative humidifiers that release water vapor but don't aerosolize the bacteria in a mist.

High bacteria levels have been found in wet building materials and can be the cause of offensive odors. Whether the bacteria causes disease depends upon the strain and levels of bacteria present. Of course, if the source of the water is from the sanitary sewer, we should assume that disease-causing bacteria are present and implement the appropriate preventative and corrective actions. Corrective action includes containment of the contaminated area and removal of all impacted porous building materials (e.g. carpet, plasterboard) using asbestos abatement-type techniques and personal protection. After removal, all remaining surfaces should be disinfected with a 10% bleach solution followed by a clean water rinse.

Viruses are primarily transmitted from person to person by coughing, sneezing, and shaking hands. Viruses are most efficiently transmitted during the winter months when the relative humidity level is below 30%. In the northern part of the United States, this occurs inside buildings from late October through part of April. The spread of flu and cold viruses can easily be minimized with frequent hand washing with moisturizing soap and by covering the nose and mouth when sneezing or coughing.

Aside from their disagreeable appearance and potential to bite or sting, insects can affect the indoor environment with their fecal droppings. Fecal droppings contain allergens, which, if present at relatively high levels, may cause allergic-like reactions in sensitive individuals.

Most insects are large enough to be noticed, and measures are usually implemented to eradicate them. However, some insects are too small to be readily seen. One such insect is the dust mite, which feeds on shed skin cells. Its fecal droppings are a strong allergen, and many people have been diagnosed with a dust mite allergy. Dust mites proliferate in an environment that is warm and relatively humid, and where people, animals, and fabrics are present.

The best means for controlling dust mite populations include:

• Frequent cleaning of carpet and other textiles with a HEPA-filtered vacuum cleaner
• Maintaining the indoor humidity at relatively low levels. Dust mites tend to withdraw from areas with relative humidity of less than 50%

Cockroach saliva and feces have also been identified as sources of allergens in the indoor environment. Aside from controlling cockroach populations through pest management, cleaning with a HEPA-equipped vacuum and other good housekeeping practices will help to reduce allergen levels.

With our ever-increasing level of understanding of the health impact of biological contaminants in indoor environments, it's crucial that building owners and risk managers develop a comprehensive plan to reduce exposure to indoor biological agents. Simple steps, such as regular and daily cleaning of buildings, maintenance of the building envelope to reduce water infiltration, increasing the quantity of outside air, and conducting regular and routine preventive maintenance on HVAC systems, will assure that health risks to building occupants and potential liability for the building owner are minimized.