I Indoor ndoor and and Built uilt Environment Editorial Studies of relationship between ventilation, pollution exposure and environmental health of buildings Wei Ye 1,2 , Jun Gao 2 , Xu Zhang 2 and Chuck Wah Yu 3 In modern society, exposure to multiple airborne pollu- tants is almost inevitable as we spend majority of our time living, working and travelling within enclosed indoor environments. The exposure to these ubiquitous contaminants, e.g. bioeffluents, particulate matter (PMs), formaldehyde (HCHO) and other volatile or semi-volatile organic compounds (VOCs and SVOCs), mould, radioactive gases, etc., could adversely affect occupants’ health, comfort and productivity. 1–9 Ventilation and ventilation of conditioned air are often the primary solution to reduce and ameliorate concen- trations of undesirable compounds. 10,11 However, some- times, indoor air pollutants could not be totally eliminated by ventilation alone, what ventilation can do best is to reduce concentrations of these pollutants to the recommended or regulated levels given by indoor air quality guidelines or by national standards. There have been debates about whether a consider- ation of health effects should be included when specify- ing minimum ventilation rate in standard building codes or regulations; this has been largely resolved with a consensus to specify ventilation to meet require- ments for both comfort (mainly odour and irritation) and health effects in relation to concentrations of spe- cific airborne pollutants, such as NO 2 , CO, CO 2 , PM 10 , HCHO, TVOC (total VOCs), some aromatic hydrocar- bons, e.g. BTEX (benzene, toluene, ethylbenzene and xylenes), NH 3 (ammonia), moulds and other microbes, radon, bioeffluents, tobacco smoke, etc. 12–14 Correspondingly, the targeted concentration limits should be considered as not harmful to occupants’ health and do not negatively impact occupants’ percep- tion of their indoor environment. 12 In this sense, to determine an airflow rate (or ventilation rate) that can be used to maintain a healthy and comfortable environment is practically the definition of the required minimum ventilation rate for a specific building. Minimum ventilation rate is often a term used in guidelines, regulations, standards or even legislations to ensure indoor air quality (IAQ) in buildings is acceptable at a broader scale. 15–17 The easy part of designing ventilation rate for a building is to interpret the minimum ventilation rate as minimum ventilation rate per person (m 3 h 1 per person), minimum ventila- tion rate per area (m 3 h 1 m 2 ) or air change rate (ACH, h 1 ) based on specific purposes. The more dif- ficult part is to determine an appropriate rate for a specific building, even after indoor emission sources have been carefully studied. Probably the impossible aspect is to set a reasonable rate that could cover com- prehensively all civic buildings including residential, public and commercial buildings, and to specify this ventilation rate in formal or less formal mandatory or recommended standard documents. The kernel of this issue is to consider the various health objectives, to support actions on determining appropriate ventilation rates to control indoor concen- trations of various airborne contaminants to assure acceptable indoor air quality for occupants. First, health effects of many indoor contaminants or contam- inant mixtures are unknown and many will stay unknown for a very long time. 12,18–20 This level of ignor- ance would substantially contribute to a less reliable or undecidable concentration limit for many contaminants for indoor environments. Yet, the dilemma will still remain in the coming future. On one hand, a great deal of time and financial investments have been devoted to health end-point studies, making it impossible to exhaust all contaminants of concerned. On the other hand, indeed, the government can ban certain chemicals from manufacturing processes; however, the industry could react by inventing new products with slightly dif- ferent chemical formulae, and making these new prod- ucts available to the market. Thus, we would have a continuous uncertainty regarding the composition of 1 State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai, P. R. China 2 School of Mechanical Engineering, Tongji University, Shanghai, P. R. China 3 International Society of the Built Environment (ISBE), Milton Keynes, UK Corresponding author: Xu Zhang, School of Mechanical Engineering, Tongji University, Shanghai, P. R. China. Email: xuzhang@tongji.edu.cn Indoor and Built Environment 2017, Vol. 26(2) 147–151 ! The Author(s) 2016 Reprints and permissions: sagepub.co.uk/ journalsPermissions.nav DOI: 10.1177/1420326X16687602 journals.sagepub.com/home/ibe