Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity

In epidemiological prospective modelling, assessing the hypothetical infectious quanta emission rate (Eq) is critical for estimating airborne infection risk. Existing Eq models overlook environmental factors such as indoor relative humidity (RH) and temperature (T), despite their importance to dropl...

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Main Authors: Vitor Lavor, Jianjian Wei, Omduth Coceal, Sue Grimmond, Zhiwen Luo
Format: Article
Language:English
Published: Elsevier 2025-04-01
Series:Environment International
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Online Access:http://www.sciencedirect.com/science/article/pii/S0160412025001308
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author Vitor Lavor
Jianjian Wei
Omduth Coceal
Sue Grimmond
Zhiwen Luo
author_facet Vitor Lavor
Jianjian Wei
Omduth Coceal
Sue Grimmond
Zhiwen Luo
author_sort Vitor Lavor
collection DOAJ
description In epidemiological prospective modelling, assessing the hypothetical infectious quanta emission rate (Eq) is critical for estimating airborne infection risk. Existing Eq models overlook environmental factors such as indoor relative humidity (RH) and temperature (T), despite their importance to droplet evaporation dynamics. Here we include these environmental factors in a prospective Eq model based on the airborne probability functions with emitted droplet distribution for speaking and coughing activities. Our results show relative humidity and temperature have substantial influence on Eq. Drier environments exhibit a notable increase in suspended droplets (cf. moist environments), with Eq having a 10-fold increase when RH decreases from 90 % to 20 % for coughing and a 2-fold increase for speaking at a representative summer indoor environment (T = 25° C). In warmer environments, Eq values are consistently higher (cf. colder), with increases of up to 22 % for coughing and 9 % for speaking. This indicates temperature has a smaller impact than humidity. We demonstrate that indoor environmental conditions are important when quantifying the quanta emission rate using a prospective method. This is essential for assessing airborne infection risk.
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spelling doaj-art-84881b08b2bc4b1ba43a2b41fb48eeda2025-08-20T03:14:54ZengElsevierEnvironment International0160-41202025-04-0119810937910.1016/j.envint.2025.109379Quanta emission rate during speaking and coughing mediated by indoor temperature and humidityVitor Lavor0Jianjian Wei1Omduth Coceal2Sue Grimmond3Zhiwen Luo4School of the Built Environment, University of Reading, Reading, UKInstitute of Refrigeration and Cryogenics, Key Laboratory of Refrigeration and Cryogenics Technology of Zhejiang Province, Zhejiang University, Hangzhou, ChinaDepartment of Meteorology, University of Reading, Reading, UKDepartment of Meteorology, University of Reading, Reading, UKWelsh School of Architecture, Cardiff University, Cardiff, UK; Corresponding author at: Welsh School of Architecture, Cardiff University, Cardiff, UK.In epidemiological prospective modelling, assessing the hypothetical infectious quanta emission rate (Eq) is critical for estimating airborne infection risk. Existing Eq models overlook environmental factors such as indoor relative humidity (RH) and temperature (T), despite their importance to droplet evaporation dynamics. Here we include these environmental factors in a prospective Eq model based on the airborne probability functions with emitted droplet distribution for speaking and coughing activities. Our results show relative humidity and temperature have substantial influence on Eq. Drier environments exhibit a notable increase in suspended droplets (cf. moist environments), with Eq having a 10-fold increase when RH decreases from 90 % to 20 % for coughing and a 2-fold increase for speaking at a representative summer indoor environment (T = 25° C). In warmer environments, Eq values are consistently higher (cf. colder), with increases of up to 22 % for coughing and 9 % for speaking. This indicates temperature has a smaller impact than humidity. We demonstrate that indoor environmental conditions are important when quantifying the quanta emission rate using a prospective method. This is essential for assessing airborne infection risk.http://www.sciencedirect.com/science/article/pii/S0160412025001308Expiratory dropletsQuanta emission rateQuantaIndoorLong-range airborne transmission
spellingShingle Vitor Lavor
Jianjian Wei
Omduth Coceal
Sue Grimmond
Zhiwen Luo
Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
Environment International
Expiratory droplets
Quanta emission rate
Quanta
Indoor
Long-range airborne transmission
title Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
title_full Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
title_fullStr Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
title_full_unstemmed Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
title_short Quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
title_sort quanta emission rate during speaking and coughing mediated by indoor temperature and humidity
topic Expiratory droplets
Quanta emission rate
Quanta
Indoor
Long-range airborne transmission
url http://www.sciencedirect.com/science/article/pii/S0160412025001308
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AT jianjianwei quantaemissionrateduringspeakingandcoughingmediatedbyindoortemperatureandhumidity
AT omduthcoceal quantaemissionrateduringspeakingandcoughingmediatedbyindoortemperatureandhumidity
AT suegrimmond quantaemissionrateduringspeakingandcoughingmediatedbyindoortemperatureandhumidity
AT zhiwenluo quantaemissionrateduringspeakingandcoughingmediatedbyindoortemperatureandhumidity