Development of an Investigation Method for Evaluation of Microbiological Indoor Air Quality

An investigation method to evaluate microbiological air quality has been developed; it involved a compiling building inspections checklist and occupants questionnaires, choosing sites, sampling frequency and analysis procedures. This method has been applied in a representative building with HVAC system and open-space offices. Air samples and microclimate parameters were collected at the same time. Airborne microorganisms levels ranged from 50 CFU⋅m to 500 CFU⋅m. A high fungal concentration (>1000 CFU⋅m) was found associated with a winter flood event. Statistical analysis showed a significant seasonal and daily variation of airborne microorganisms. Staphylococcus and Micrococcus were the most common bacterial genera and Penicillium was the most widespread fungal genus. Samples collected at HVAC system levels demonstrated an overall good microbiological removal efficiency of the device, except for unusual events (flood). This study highlights the importance, for air quality control, of a preventive approach based on microbiological risk analysis and critical point control. INDEX TERMS Bioaerosols, HVAC, airborne bacteria, airborne fungi, health effects INTRODUCTION Indoor air quality is becoming an increasingly important issue for occupational and public health (Clarke and Nikkel, 1995). Health effects related to indoor air microbiological quality have increased, with a tendency to some energy saving measures provided for buildings such as tightly sealing, air recirculation and introduction of HVAC (Heating Ventilation Air Conditioning) (Nathanson, 1995). In addition, ageing population, the increasing number of sensitive individuals and a tendency to spend more time indoors (90% of their time) further worsen this problem (Seltzer, 1995). HVAC modifies air quality and can affect indoor microorganisms concentration (Parat, Perdrix, Fricker-Hidalgo, et al., 1997). Airborne microorganisms may be responsible for specific infections, Building Related Illnesses (Legionellaire’s disease, aspergillosis, hypersensivity pneumonitis, etc.) and can be involved in Sick Building Syndrome (Stetzenbach, 1997). * Contact author email: [email protected] Proceedings: Indoor Air 2002