The mould Stachybotrys chartarum has been found to be associated with idiopathic pulmonary haemorrhage in infants and indoor exposure has also been linked to other pulmonary diseases, including allergies and asthma. S. chartarum has been studied both for toxin production and its occurrence in water-damaged buildings. Growth of S. chartarum on building materials such as gypsum wallboard has been frequently documented. Given that there may be a high frequency of occurrence and so the risk of exposure, environmental factors leading to the growth of S. chartarum have been studied. Samples of commonly used building materials were sterilised, inoculated with S. chartarum and exposed to controlled levels of relative humidity and wetting. A quantitative analysis of viable S. chartarum was performed on the building materials during a 7-month period. The results indicate that for environments with a relative humidity below total saturation, wetting was necessary for visible growth to occur. Conversely, high levels of relative humidity without wetting did not initiate growth. Porous materials, after becoming sufficiently wet and measuring saturation on a moisture meter, exhibited mould growth in every experiment conducted.

Ultraviolet irradiation has commonly been used in the indoor environment to eliminate or control infectious diseases such as tuberculosis in medical care facilities. Heating, ventilating, and air-conditioning (HVAC) system components such as duct-liners, cooling coils, drip-pans, interior insulation, and areas subjected to high levels of moisture can create an environment that is prone to biological contamination. Air supplied to indoor environments can carry biological contaminants that can expose numerous building occupants to pathogenic organisms. Possible terrorist activities could release biological agents into ambient air, or directly into a building environment, or HVAC system may expose multitudes of individuals to dangerous pathogens. The use of germicidal ultraviolet lamps (UVGI) in commercial and residential HVAC systems has increased. A method to determine the antimicrobial efficacy of UVGI irradiation was developed and tested on the surface of agar plates with eight varieties of Bacillus bacteria spores. Bacillus anthracis surrogates were used for their expected similar inactivation responses to UVGI irradiation. The percent kill and k value for each organism was calculated for various periods of exposure.Résumé : L'irradiation aux rayons ultraviolets a été fréquemment utilisée dans l'environnement intérieur afin d'éliminer ou de contrôler les maladies infectieuses, telles que la tuberculose, dans les établissements de soins médicaux. Les composantes du système CVC (chauffage, ventilation, climatisation), telles que les revêtements des conduits, les serpentins refroidisseurs, les bacs d'égouttement, l'isolation intérieure et les zones soumises à de forts niveaux d'humidité, peuvent créer un environnement prédisposé à la contamination biologique. L'air acheminé dans les environnements intérieurs peut transporter des contaminants biologiques, pouvant ainsi exposer plusieurs occupants du bâtiment à des organismes pathogènes. Des activités terroristes possibles pourraient libérer des agents biologiques dans l'air ambiant, ou directement dans l'environnement du bâtiment, ou encore le système de chauffage, ventilation et climatisation pourrait exposer une multitude de personnes à des pathogènes dangereux. L'utilisation des lampes germicides aux rayons ultraviolets dans les systèmes CVC commerciaux et résidentiels s'est accrue. Une méthode pour déterminer l'efficacité antimicrobienne de l'irradiation par des lampes germicides aux rayons ultraviolets a été développée et mise à l'épreuve sur la surface de plaques à la gélose comportant huit variétés de spores Bacillus. Des substituts de B. anthracis ont été utilisés pour leur réponse d'inactivation similaire prévue à l'irradiation par des lampes germicides aux rayons ultraviolets. Le pourcentage de destruction et la valeur k pour chaque organisme ont été calculés pour différentes périodes d'exposition.

The goal of this research was to reduce occupant exposure to indoor mold through the efficacy testing of antimicrobial paints. An accepted method for handling Stachybotrys chartarum-contaminated gypsum wallboard (GWB) is removal and replacement. This practice is also recommended for water-damaged or mold-contaminated GWB but is not always followed completely. The efficacy of antimicrobial paints to eliminate or control mold regrowth on surfaces can be tested easily on nonporous surfaces. The testing of antimicrobial efficacy on porous surfaces found in the indoor environment, such as gypsum wallboard, can be more complicated and prone to incorrect conclusions regarding residual organisms. The mold S. chartarum has been studied for toxin production and its occurrence in water-damaged buildings. Research to control its growth using seven different antimicrobial paints and two commonly used paints on contaminated, common gypsum wallboard was performed in laboratory testing at high relative humidity. The results indicate differences in antimicrobial efficacy for the period of testing, and that proper cleaning and resurfacing of GWB with an antimicrobial paint can be an option in those unique circumstances when removal may not be possible.