A STUDY ON THE IMPACT OF FILTRATION ON SOME KNOWN AIR CONTAMINANTS

Abstract

Filtration can be practical means of maintaining indoor pollution level in buildings with mechanical ventilation systems. An intervention study was conducted in two new office buildings to examine the impact of different filtration strategies on dust distribution, Total volatile organic compounds (TVOCs) and microbial contamination. Intervention was carried out within the air-handling unit at selected floor in both buildings where the filtration methods adopted were normal media filter, electrostatic precipitation filter and activated carbon filter. The size-differentiated particulate distribution was determined using an optical particle counter while the Andersen single stage sampler was used to assay bioaerosols. As for sampling of TVOCs, a multi-Gas monitor and multi-point Sampler & Doser were used. The effectiveness of the various filtration strategies were compared based on their removal efficiencies for particles over a wide range of aerodynamic sizes, Total viable Bacteria counts and some common chemical pollutants. From the results, there is strong indication that electrostatic filter is superior to normal media filter for the removal ofdust particles, especially for dust size in the regime of < 1µm, as well as viable bacteria and yeast & molds. Further enhancement of electrostatic filters with an additional layer of carbon filters augments their removal efficiencies and produce additional propensity for the removal of TVOCs.