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The Source of Sick Buildings

Environmental Health Perspectives, 197(2) February 1999

Indoor fungal contamination has been shown to produce allergies in building occupants. While fungi have also been suspected of playing a role in sick building syndrome (SBS), a health condition that results from poor indoor air quality, few studies to date have been able to verify this link. A recent study, however, links SBS with elevated indoor levels of the fungi Penicillium and Stachybotrys, both of which have been implicated in respiratory diseases such as asthma and pulmonary hemosiderosis. The research, which was published in the September 1998 issue of Occupational and Environmental Medicine, is the most comprehensive SBS study to date, having examined more buildings than any previous study.

David Straus and colleagues at Texas Tech University Health Sciences Center in Lubbock conducted a 22-month in-depth study of 48 schools that had reported concerns about health and indoor air quality to the indoor air quality company with which the university researchers are affiliated. The schools are located along the Gulf of Mexico and the Atlantic seaboard of the United States.

The researchers disseminated a questionnaire to the staff of the schools asking about health complaints, timing patterns of symptoms, and particular areas of the schools in which staff members experienced symptoms. About 30% of all staff reported symptoms or complaints, most commonly nasal drainage, congestion, and itchy, watery eyes. Most of the staff said they experienced these symptoms only while in the building. More than half of those who reported symptoms also noted increased incidences of respiratory infections such as tonsillitis, bronchitis, and, in some cases, pneumonia.

The researchers also measured humidity, particulate matter, carbon dioxide, and chemicals such as formaldehyde, nitrogen dioxide, hydrogen sulfide, sulfur dioxide, and carbon monoxide, both indoors and in the outdoor areas surrounding the schools. They examined the schools' heating, ventilation, and air conditioning (HVAC) systems, and took swab samples and air samples at sites that had been wetted and showed mold growth.

In some of the schools, Straus's team discovered that the major factor that correlated with the health complaints was increased indoor levels of Penicillium and Stachybotrys. Straus says that, ideally, the amount of fungi inside a building should be much lower than that outside. In many of the schools, the levels of the two fungi were much higher inside than outside. These schools were found to conduct very little HVAC maintenance and many had active water leaks, creating the damp conditions in which fungi thrive.

Twenty schools showed significant increases in the amounts of Penicillium species in indoor air samples of complaint areas. The mean indoor relative humidity in these areas was higher than in noncomplaint areas and higher than outdoor relative humidity. At 11 schools, the researchers found heavy growth of Stachybotrys molds on swabs taken from under damp carpets and vinyl wall coverings and on walls. This organism produces a mycotoxin that has been shown to affect the central nervous system and cause damage throughout the body.

In the remaining schools, Straus found that the fungal ratios of indoor and outdoor air samples were not significantly different. However, swab samples in many of these schools detected heavy growth of the Penicillium species as well as another type of fungi, Cladosporium. According to the report, these findings indicate possible fungal growth inside the schools and a potential indoor air quality problem.

Once remedial action was completed in the schools, the number of health complaints decreased. Remedial action involved replacing building materials that showed physical deterioration, cleaning surfaces showing microbial contamination and treating them with an approved disinfectant, and cleaning the HVAC systems in accordance with National Air Duct Cleaners Association standards. The researchers followed up with air and swab samples within 60 days of the cleaning and again six months later. They found that fungal ratios had returned to acceptable, normal levels, and that the percentage of staff complaining of symptoms had dropped from 30% to less than 3%.

To prevent fungal contamination, Straus says, the solution is very simple: "Get water out of the building and properly maintain the HVAC system." He says that building maintenance is also important because problems such as roof leaks and broken pipes also increase humidity, allowing fungi to thrive.

Straus says the team did not disseminate the surveys to students due to the difficulty of administering them to children and the unreliability of children's responses. He says, however, "We believe that children are affected even more [by the fungi] because they are still growing." While research on the effects of fungi on children's health is sparse, a 1993 case in which experts believed that a strain of Stachybotrys caused adverse health effects in many infants spurred public interest. Several babies in the Cleveland, Ohio, area who were found to have been exposed to the fungus developed pulmonary hemosiderosis. This disease is marked by bleeding of the lungs--which can lead to coughing up blood, nose bleeds, chronic cough and congestion, and anemia--and caused the death of many of the infants.

National Institute of Environmental Health Science. 1999. Sources of Sick Buildings. Environmental Health Perspectives 107:2, February 1999.




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