Impact of ventilation and recirculation rates on exposure to and intake of ozone and its initiated chemistry products: Mass balance model evaluation

A mass balance model is used to examine the impact of two ventilation (1 /h and 2 /h) and recirculation (7 /h and 14 /h) rates on concentrations, exposure to and intake of ozone (of outdoor origin) and secondary organic aerosols (SOA) derived from the ozone initiated chemistry in indoor environment. Measured data from several experimental studies conducted by the authors in a 236m3 field environmental chamber (FEC) configured to simulate an office are used for the mass balance model evaluations. At steady state, increase in ventilation rate increases exposure to and intake of indoor ozone, but reduces exposure to and intake of SOA. Increase in recirculation rate reduces exposure to and intake of ozone and SOA. Increase in outdoor ozone concentration increases exposure to and intake of ozone and SOA. As expected, indoor ozone and SOA concentrations are lower for human occupancy scenario than non-human occupancy scenario. Interestingly, human sink of ozone and SOA is much lower at higher recirculation rate than at lower recirculation rate - this is a new finding that has not been reported in the literature.