建築物內外的空氣交換可帶入室外的空氣，稀釋掉室內的空氣污染物，改善室內的空氣品質。然而 室外空氣也有可能帶著汙染物進入室內，其中懸浮微粒就是其中一項評估空氣品質的因子，為了瞭解粒狀汙染物是如何由室外進入室內，以及在室內的停留、離開等情況如何進行，必須對建築物通風與汙染物傳輸機制有更深入的瞭解。本研究採用流體動力學模式研究建築物自然通風與外部汙染物傳輸之間的關係。模擬流況以貫流通風為主研究成果顯示當室外顆粒汙染源愈靠近建築物 汙染物進入室內的比例由增加至。當建築物長度增加，通風量隨之減少，室外汙染物進入室內的比例下降；當汙染源位置距離建築物的長度減少，顆粒汙染物進入室內的比例隨之增加。當汙染源位於街谷中 隨著間距的增加，下風處的建築物的通風量也隨之增加。當建築物間距 S/H = 2時，建築物間的風速十分微弱，顆粒汙染物在街谷中停留時間變長，顆粒有較高的機率進入建築物。但當建築物間距 S/H ≥ 4時 隨著間距的增加顆粒汙染物進入下風處的建築物內部的比例增加。

The natural ventilation of buildings can bring in the fresh air, dilute indoor air pollutants, and improve indoor thermal comfort. However, outdoor air may also bring pollutants into the buildings. The particular matter is one of the pollutants that could significantly affect indoor air quality. Therefore, it is necessary to have a deeper understanding of the relationship between natural ventilation and pollutant transport mechanisms. This study uses a computational fluid dynamics (CFD) model to investigate how the outdoor particulate pollutants enter naturally ventilated buildings. The research results show that and the ventilation rate and the entrance rate of outdoor PM pollutants decrease when the length of the building increases. In addition, the deposition rate of indoor PM2.5 rises with the increasing building length due to the stagnant air inside the long buildings. Furthermore, when the pollution source is located in the street canyon, the ventilation rate of downwind buildings and the entrance rate of PM pollutants decrease as the building spacing S decreases. But when the building spacing S/H = 2, the wind speed between buildings is very weak, the PM pollutants stay in the street canyons longer, and the pollutants have a higher chance of entering the building.

[1] O. Hanninen and P. Goodman, Outdoor air as a source of indoor pollution, Indoor Air Quality, edited by R.M. Harrison and R.E. Hester, 2019; 35-65.
[2] B. Brunekreef, N.A. Janssen, J. de Hartog, H. Harssema, M. Knape, P. van Vliet, Air pollution from truck traffic and lung function in children living near motorways, Epidemiology 1997; 8 (3):298-303. doi:10.1097/00001648-199705000-00012.
[3] R.J. Kopperud, A.R. Ferro & L.M. Hildemann. Outdoor versus indoor contributions to indoor particulate matter (PM) determined by mass balance methods. J. Air & Waste Management Association, 2004; 54 (9): 1188-1196. doi.org/10.1016/j.Sc.2010.00372.
[4] C.R. Chu, Y.H. Chiu, Y.J. Chen, Y.W. Wang, and C.P. Chou, Turbulence effects on the discharge coefficient and mean flow rate of wind-driven cross ventilation, Building and Environment, 2009; 44: 2064-2072. doi.org/10.1016/j.buildenv.2009.02.012.
[5] M. Simoni, L. Carrozzi, S. Baldacci. The Po River Delta (North Italy) indoor epidemiological study: Effects of pollutant exposure on acute respiratory symptoms and respiratory function in adults. Archives of Environmental Health: An International Journal. 2002; 57 (2), 130-136. doi.org/10.1080/00039890209602928.
[6] B. Blocken, T. Stathopoulos, J.P.A.J. van Beeck, 2016. Pedestrian-level wind conditions around buildings: Review of wind-tunnel and CFD techniques and their accuracy for wind comfort assessment. Building and Environment. 2016; 100 (1): 50-81. doi.org/10.1016/j.buildenv.2016.02.004.
[7] B. Zhao, Y. Zhang, X.-T Li, X.-D Yang, D.-T Huang. Comparison of indoor aerosol particle concentration and deposition in different ventilated rooms by numerical method. Building and Environment. 2004; 39 (1). doi.org/10.1016/j.buildenv.2003.08.002.
[8] Z. Zhang, Q. Chen. Experimental measurements and numerical simulations of particle transport and distribution in ventilated rooms. Atmospheric Environment. 2006; 40 (18): 3396-3408. doi.org/10.1016/j.atmosenv.2006.01.014.
[9] N.P. Gao, J.L Niu, M. Perino, P. Heiselberg. The airborne transmission of infection between flats in high-rise residential buildings: Particle simulation. Building and Environment. 2009; 44 (2): 402-410. doi.org/10.1016/j.buildenv.2008.03.016.
[10] T.J. Chang, H.M. Kao, Y.F. Hsieh. Numerical study of the effect of ventilation pattern on coarse, fine, and very fine particulate matter removal in partitioned indoor environment. J. Air Waste Management Assoc. 2007, 57(2):179-89. doi:10.1080/10473289.2007.10465311.
[11] T.J. Chang, Y.F. Hsieh, H.M. Kao. Numerical investigation of airflow pattern and particulate matter transport in naturally ventilated multi-room buildings. Indoor Air. 2006; 16 (2): 136-152. doi.org/10.1111/j.1600-0668.2005.00410.x.
[12] B. Hong, H. Qin, B. Lin. Prediction of Wind Environment and Indoor/Outdoor Relationships for PM2.5 in Different Building–Tree Grouping Patterns. Atmosphere. 2018; 9 (2): 39. doi.org/10.3390/atmos9020039.
[13] V. Yakhot and S.A. Orszag. Renormalization group analysis of turbulence. I. Basic theory. Journal of scientific computing. 1986; 1, 3-51.
[14] Cunningham, E. On the velocity of steady fall of spherical particles through fluid medium. Proceeding of the royal society A. 1910. doi.org/10.1098/rspa.1910.0024.
[15] P.J. Richards, R.P. Hoxey, L.J. Short. Wind pressures on a 6 m cube. J. Wind Eng. Ind. Aerodyn. 2001; 89 (14-15): 1553-1564.
[16] P.J. Richards, R.P. Hoxey. Pressures on a cubic building—Part 1: Full-scale results. J. Wind Eng. Ind. Aerodyn. 2012; 102, 72-86.
[17] H. Irtaza, R.G Beale, M.H.R. Godley, A. Jameel. Comparison of wind pressure measurements on Silsoe experimental building from full-scale observation, wind-tunnel experiments and various CFD techniques. 2013; 5 (1).
[18] W.Z. Lu, T. A.T. Howarth, Nor Adam, S.B. Riffat. Modeling and measurement of airflow and aerosol particle distribution in a ventilated two-zone chamber. 1996; 31 (5): 417-423.
[19] Z.F. Tian, J.Y. Tu, G.H. Yeoh, R.K.K. Yuen. Numerical studies of indoor airflow and particle dispersion by large Eddy simulation. 2007; 42 (10): 3483-3492.
[20] F.J. Chen, S.C.M. Yu, A.C.K. Lai. Modeling particle distribution and deposition in indoor environments with a new drift-flux model. Atmospheric Environment. 2006; 40, 357-367.
[21] A.C.K. Lai, K. Wang, F.Z. Chen. Experimental and numerical study on particle distribution in a two-zone chamber. Atmospheric Environment. 2008; 42, 1717-1726.