Size-dependent particulate matter indoor/outdoor relationships for a wind-induced naturally ventilated airspace

We applied a simple size-dependent indoor air quality model associated with measured outdoors particulate matter (PM) profiles and potential loss mechanisms to characterize PM indoor/outdoor (I/O) relationships for wind-induced naturally ventilated residences in Taiwan region. The natural ventilation rate was quantified by the opening effectiveness for sidewall opening and covered ridge with sidewall-opening-type homes. The measured results demonstrate that integrated PM10 and PM2.5 mass concentrations for the urban area are 39.2 and 3.13 μg m−3, respectively, whereas for the suburban area are 75.76 and 69.87 μg m−3, respectively. The most significant removal mechanisms included natural ventilation through and particle deposition on indoor surfaces. The predicted average PM mass I/O ratios were 0.56 and 0.42 for PM2.5 and PM10, respectively. We also employed published data on mass-weighted size distributions for specific chemical constitutes of PM, sulfate and nitrate, to predict PM I/O ratios in the central Taiwan region; the resulting values ranged from 0.22 to 0.43 and 0.27 to 0.36 for sulfate and nitrate, respectively. Our results demonstrate that the PM I/O ratios for a wind-induced natural ventilated airspace depend strongly on the ambient particle distributions, building openings design (e.g. height-to-length ratio of openings and roof slope), wind speed, wind angle of incidence, and outdoor PM metrics.