THE SICK BUILDING SYNDROME AND HVAC SYSTE MS - MVOC FROM AIR FILTERS

Growth and emissions of volatile metabolites of microorganisms on air filters are suspected to contribute to health complaints in ventilated rooms. To prove the microbiological production of volatile organic co mpounds (MVOC), concentrations of aldehydes and ketones were determine d in two large HVAC systems. The in situ derivated aldehydes and keton es (as 2,4-dinitrophenyl-hydrazones) were analysed by HPLC and UV dete ction. The detection limit of each compound was 1 ppb (margin of error < 10%). Field measurements were carried out before and after the pref ilters and the main filters, respectively, to investigate whether alde hydes and ketones increase in concentration after filters of HVAC syst ems. First results show that the compounds formaldehyde, acetaldehyde and acetone could be detected before and after the filters. The concen trations of these VOC after the filters were significantly increased - as a mean over twenty measurements -, especially as far as filters ma de of glass fibre are concerned. However the found concentrations were low and mostly comparable to outdoor findings. In simultaneous labora tory experiments pieces of used filter material of one HVAC system and unused filter pieces (for blank values) were examined in small incuba tion chambers to investigate the possible production of MVOC. For the incubation a temperature of 20 degrees C and a relative humidity of 95 % was chosen. In these experiments an almost identical spectrum of com pounds (formaldehyde and acetone) was found as in the field measuremen ts. The concentrations of these compounds were higher in the chambers with the used filter pieces. The concentration of acetone ranged up to almost 12 mg/m(3). - As our field experiments correspond with our lab oratory experiments, we assume that the microbial production of volati le organic compounds in HVAC systems under operating conditions is pos sible.