EFFECT OF RECIRCULATION RATE AND FILTERS ON THE INDOOR ENVIRONMENT

Abstract

The severity of symptoms associated with the sick building syndrome (SBS) and other related health problems in the occupants of office building might be due to the state of filters (new and used) and the rate at which used air is replaced with “fresh” outdoor air. This might be an important issue for the tropics whereby 90% of the used air is recirculated and only 10% is taken from outdoor air for dilution. For this reason, there is a need to understand the effect of the relationship between the state of filter and recirculation rate under recirculation of conditioned air scenario on particle concentrations and particle size distribution. This may provide an understanding of how building occupants’ health could be affected. Studies were thus carried out using different states of filters under 2 scenarios: low recirculation and high ventilation rates, and high recirculation and low ventilation rates. The findings suggest that high recirculation rate lead to a lower production of SOA concentration which coincides with the hypothesis 2: higher recirculation rates will result in lower production of SOA in ventilation systems and indoor space. However, the results show that used filter does not generate more SOA than the no/new filter scenarios. This may be due to insufficient time duration of the experiment for desorption of used filter to occur. Furthermore, SOA particles produced during limonene/ozone reactions are smaller than the human red blood cell thus implying that these particles may have adverse health effect on humans.