Campos, LC

Canales, ME

Ciric, L

Colbeck, I

Nasir, ZA

UCL Discovery

Environmental monitoring to inform built environments vulnerability to airborne diseasetransmissionZ.A.Nasir1, L.Campos1, M. Canales1, L.Ciric1 and I. Colbeck21Department of Civil, Environmental and Geomatic Engineering, University College London, WC1E 6BT, UK2School of Biological Sciences, University of Essex, Colchester, Essex, CO4 3SQ, UKKeywords: Air Health, Particles, CO2, Offices.Presenting author email: Z.nasar@ucl.ac.ukIn the 21st century, environmental heath in the builtenvironment is central to public health. The way wedesign, construct, use and manage indoor environmentscan have substantial impact on our wellbeing. Of thewide range of indoor air contaminants, infectious agentsare of the greatest concern due to their potential to causehuge damage to global public health. In recent years wehave witnessed the emergence of new diseases (e.g.influenza H1N1 and SARS) and their potential to causewide spread disease in societies across the globe. Theuncertainty about when a pandemic may occur and theunpredictability of its severity leave no option but toprepare in advance. A range of environmental factorscan enhance the probability of disease transmission inbuilt environments. These include: prolonged exposureto infectious individuals/sources in small enclosedspaces, inadequate ventilation, and recirculation ofcontaminated air. Therefore, there is an urgent need todevelop practical tools to assess the relative risk thatbuilt environments pose in infection transmission.The present study aims to highlight the use ofenvironmental monitoring as a tool to assess air health inbuilt environments and to inform their vulnerability toairborne disease transmission. Measurements werecarried to monitor the number concentration of particlesin 6 different sizes (Lighthouse laser particle counter,5016), CO2, temperature, relative humidity (IAQ4 – BWTechnologies) and airborne culturable bacteria(Andersen 6 stage sampler) in a mechanically ventilatedoffice during October 2012 under two differentscenarios: ventilation system off and on. The floor areaand volume of the office was 28 m2 and 80 m3,respectively, and it had five work stations.The summary of results presented in Figure 1 andTable 1 clearly shows the impact of poor ventilation onthe concentration of airborne bacteria, particles in all thesize ranges and CO2.0501001502002503000 1 2 3 4 5 6 7 8 9 10CFU/m3Particle Size (µm)Ventilation Off Ventilation OnFigure1.Size distribution of culturable airborne bacteriaTable 1. Hourly average number concentration ofparticles and CO2 in a mechanically ventilated officeNUMBER CONCENTRATION (#/m3)Ventilation OFF Ventilation ONMean SD Mean SDDay Time (8.00 – 19.00)0.5 µm 8,804,986 7,511,997 265,594 112,7640.7 µm 1,459,121 1,226,868 86,991 36,8381.0 µm 358,566 160,785 79,104 38,7423 µm 41,176 28,699 21,853 13,3395 µm 5,525 5,078 4,059 2,50110 µm 2,802 3,890 2,009 1,605Night Time (20.00 – 07.00)0.5 µm 10,370,265 6,179,079 220,588 158,4890.7 µm 1,792,998 1,203,352 69,081 40,9721.0 µm 388,301 228,027 42,505 28,3743 µm 16,898 17,953 3,851 4,5115 µm 995 2,123 445 81310 µm 212 602 120 227CO2 (PPM)Overall 783 325 529 139Day 1,005 297 626 127Night 534 83 420 26Inadequate supply of outdoor air relative tooccupant density resulted in the accumulation ofparticles and CO2 in the office air. It also impactedgreatly on relative humidity. (49-63% during ventilationsystem off and 35-46% during ventilation system on). Itis evident that in the presence of an infectious source inthis built environment the occupants’ risk of exposurewill be enhanced under an inadequate ventilationscenario. It is important to highlight that very often theneed for ventilation is governed by psychological andphysiological needs of the occupants and the currentguidelines and codes proposed by different organizationson indoor air quality in work places are focused onthermal comfort and odour removal rather thanpreventing infection transmission.Environmental monitoring of airborne particlesand CO2 can play a pivotal role in evaluating air healthin built environments and identifying ill/malfunctioningelements. This can assist in the design of venue andscenario specific mitigation strategies to reducevulnerability of the built environment to airborneinfection transmission.This study was funded by the Engineering and PhysicalScience Research Council, United Kingdom, grantreference EP/G029881/1

Environmental monitoring to inform built environments vulnerability to airborne disease transmission

http://discovery.ucl.ac.uk/1508074/1/Nasir_Environmental_monitoring_buil_%20environments.pdf

Environmental monitoring to inform built environments vulnerability to airborne disease transmission

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