Air filters from HVAC systems as possible source of volatile organic compounds (VOC) - laboratory and field assays.

The study aimed to evaluate the emission of volatile organic compounds from air filters. In the first part of the project, carbonyl compounds were measured by reacting them with 2,4-dinitrophenylhydrazine. HPLC and UV detection were used for the analysis. Laboratory experiments used pieces of used and unused HVAC filters, incubated in test chambers. The used filters used in the experiments were from a filter bank of a large HVAC system in the middle of Berlin, Germany. Formaldehyde and acetone were found in higher concentrations in the test chambers filled with used filters in comparison to those with unused filters. At the prefilter and main filter banks of the two HVAC systems, parallel field measurements were carried out. In these cases measurements were carried out to investigate whether the aldehydes and ketones came from the filter material on site. It was found that after the filters of one HVAC system, formaldehyde and acetone significantly increase in concentration. Parallel experiments proved that microorganisms could survive on air filters. Concludes that a possible source of formaldehyde and acetone may be microbes.