Indoor Air 2016; 1–13 wileyonlinelibrary.com/journal/ina | 1 © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd Received: 17 May 2016 | Accepted: 11 November 2016 DOI: 10.1111/ina.12357 ORIGINAL ARTICLE Experimental analysis of the air velocity and contaminant dispersion of human exhalaion lows F. A. Berlanga | I. Olmedo | M. Ruiz de Adana Department of Chemical Physics and Applied Thermodynamics, University of Córdoba, Córdoba, Spain Correspondence F. A. Berlanga, Department of Chemical Physics and Applied Thermodynamics, University of Córdoba, Córdoba, Spain. Email: felix.berlanga@uco.es Funding informaion European Regional Development Fund (ERDF) Abstract Human exhalaion low is a potenial source of pathogens that can consitute a cross-infecion risk to people in indoor environments. Thus, it is important to inves- igate the characterisics of this low, its development, area of inluence, and the dif- fusion of the exhaled contaminants. This paper uses phase-averaged paricle image velocimetry together with a tracer gas (CO 2 ) to study two diferent exhalaion lows over ime: the exhalaion of an average male (test M) and an average female (test F), using a life-sized thermal manikin in a supine posiion. The exhalaion jets generated for both tests are similar in terms of symmetrical geometry, voricity values, jet opening angles, and velocity and concentraion decays. However, there is a difer- ence in the penetraion length of the two lows throughout the whole exhalaion process. There is also a ime diference in reaching maximum velocity between the two tests. It is also possible to see that the tracer gas dispersion depends on the momentum of the jet so the test with the highest velocity decay shows the lowest concentraion decay. All these results are of interest to beter understand cross- infecion risk. KEYWORDS contaminant dispersion, human exhalaion low, PIV, velocity and concentraion decay 1 | INTRODUCTION People spend much of their lifeime indoors where they are exposed to airborne polluion, such as VOCs (volaile organic contaminants), paricles, or biological pathogens. These pathogens can be found in- side small droplets or as paricles emited during normal human res- piratory processes. 1 Many researchers have found evidence of the airborne transmis- sion routes of diferent diseases. 2–5 In indoor environments, there are many parameters that directly inluence the dispersion of exhaled con- taminants and therefore the airborne infecion route. Some of these factors, such as venilaion mode, 6–9 air change rate (ACR), 10,11 or sep- araion distance with respect to the source, 12 have been experimen- tally studied. Another key factor in the airborne transmission route of diseases is the diferent human breathing aciviies, such as exhalaion, coughing, or sneezing, as they are considered the source of potenial biological contaminants in indoor environments. In recent years, re- search has focused on increasing knowledge about these respiratory aciviies. Coughing, which is a quick process, has been studied using paricle image velocimetry (PIV). 13–16 Sneezing, an even quicker expi- raion process, was studied using a shadowgraph imaging technique and a high velocity camera to measure the maximum distance reached by the pufs and the associated maximum velociies. 17 Airlow during speaking has been studied experimentally, using a spirometer to mea- sure the resuling low, 18 and also by PIV, obtaining the velocity ield. 19 Human exhalaion is the most common breathing acivity. Several studies have found viruses in human exhalaion lows. 20–22 The par- icles sized ≤5 μm 23,24 that originated in a exhalaion process are dis- persed in the air and may potenially cause an airborne infecion risk to a person inhaling them. 25–28 Breathing has been considered as a source of contaminants in many airborne control infecion studies. 6,12,29,30 However, its characterisics