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Papers by Kwok wai Tham

Research paper thumbnail of Mitigating particulate matter exposure in naturally ventilated buildings during haze episodes

Building and Environment, 2018

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Research paper thumbnail of Balancing thermal comfort datasets: We GAN, but should we?

arXiv (Cornell University), Sep 28, 2020

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Research paper thumbnail of Viable Monkeypox virus in the environment of a patient room

We conducted a prospective environmental surveillance study to investigate the air, surface, dust... more We conducted a prospective environmental surveillance study to investigate the air, surface, dust and water contamination of a room occupied by a patient infected with Monkeypox virus (MPXV) at various stages of his illness. The patient tested positive for MPXV from a throat swab and skin lesions. Environmental sampling was conducted in a negative pressure room with 12 unidirectional HEPA air changes per hour and daily cleaning of the surfaces. A total of 179 environmental samples were collected on days 7, 8, 13, and 21 of his illness. Air, surface, and dust contamination was highest during the first eight days of the illness, with a gradual decline to the lowest contamination level by day 21. Viable MPXV was isolated from surfaces and dust samples and no viable virus was isolated from the air and water samples.SynopsisInadequate research prevail on the mode of transmission for monkeypox virus. This study reports the findings of viable monkeypox virus from the patient environment, h...

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Research paper thumbnail of Differential aerosol shedding of SARS-CoV-2 Delta and Omicron variants during respiratory activities

Data on the viral loads in respiratory aerosols from patients infected with Delta and Omicron var... more Data on the viral loads in respiratory aerosols from patients infected with Delta and Omicron variants are limited. In this study, we used an exhaled breath bioaerosol collector to collect aerosol samples in coarse (> 5µm) and fine (≤ 5µm) fractions from COVID-19 patients infected with these VOCs while doing various respiratory activities. Samples were tested via SARS-CoV-2 RT-qPCR and virus culture. Nine patients (4 Delta and 5 Omicron) were included. Viral RNA was detectable in seven participants, with greater viral loads in fine aerosols. Notably SARS-CoV-2 RNA was consistently detectable in respiratory samples of all Omicron patients despite them being fully vaccinated and mostly asymptomatic in contrast with Delta patients. Singing and talking without mask generated the greatest viral loads underscoring the transmission potential of SARS-CoV-2 and its variants via respiratory aerosols. The more consistent detection of viral RNA in Omicron-infected patients may account for it...

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Research paper thumbnail of System Evaluation in the Tropics

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Research paper thumbnail of Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing

BackgroundMultiple SARS-CoV-2 superspreading events suggest that aerosols play an important role ... more BackgroundMultiple SARS-CoV-2 superspreading events suggest that aerosols play an important role in driving the COVID-19 pandemic. However, the detailed roles of coarse (>5μm) and fine (≤5μm) respiratory aerosols produced when breathing, talking, and singing are not well-understood.MethodsUsing a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing.ResultsAmong the 22 study participants, 13 (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic patients and 1 presymptomatic patient. Viral loads ranged from 63–5,821 N gene copies per expiratory activity per patient. Patients earlier in illness were more likely to emit detectable RNA, and loads differed significantly between breathing, talking, and singing. The largest proportion of SARS-CoV-2 RNA copies was emitted by singing (53%), follow...

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Research paper thumbnail of Characterizing exhaled aerosol droplets during influenza A and B infections, and viral hemagglutinin phylogenetic analyses in a university cohort

International Journal of Infectious Diseases, 2018

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Research paper thumbnail of Mitigating particulate matter exposure in naturally ventilated buildings during haze episodes

Building and Environment, 2018

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Research paper thumbnail of Associations of Plasticized Wall and Floor Coverings With Asthma and Allergies Among Tropical Preschool Children

Epidemiology, 2007

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Research paper thumbnail of Concentration and emission rates of indoor VOCS-A comparative study between Singapore and European office buildings

Note: EPFL Reference LESO-PB-CONF-2003-002 Record created on 2005-01-12, modified on 2016-08-08

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Research paper thumbnail of The greening of Singapore's national estate

Habitat International, 1997

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Research paper thumbnail of Emission modelling and validation of VOCs' source strengths in air-conditioned office premises

Environment International, 2004

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Research paper thumbnail of BubbleZERO—Design, Construction and Operation of a Transportable Research Laboratory for Low Exergy Building System Evaluation in the Tropics

Energies, 2013

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Research paper thumbnail of Indoor air quality comparison of two air-conditioned zones served by the same air-handling unit

Building and Environment, 2002

Most indoor air quality (IAQ) investigations take an air handling unit (AHU) - based zone as the ... more Most indoor air quality (IAQ) investigations take an air handling unit (AHU) - based zone as the basic unit for investigation from the logical viewpoint that the AHU constitutes the mechanism for mixing and (cross-) transportation of pollutants within the zone. If there is very good air-mixing, as indicated by a high air exchange effectiveness, the single zone approach may

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Research paper thumbnail of A study of perceived air quality and sick building syndrome in a field environment chamber served by displacement ventilation system in the tropics

Building and Environment, 2006

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Research paper thumbnail of A comparative study of VOCs in Singapore and European office buildings

Building and Environment, 2006

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Research paper thumbnail of Interaction of convective flow generated by human body with room ventilation flow: impact on transport of pollution to the breathing zone

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Research paper thumbnail of Call-centre operator performance with new and used filters at two outdoor air supply rates

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Research paper thumbnail of Thermal effect of temperature gradient in a field environment chamber served by displacement ventilation system in the tropics

Building and Environment, 2007

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Research paper thumbnail of Indoor air quality and energy performance of air-conditioned office buildings in Singapore

Indoor Air, Nov 24, 2003

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Research paper thumbnail of Mitigating particulate matter exposure in naturally ventilated buildings during haze episodes

Building and Environment, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Balancing thermal comfort datasets: We GAN, but should we?

arXiv (Cornell University), Sep 28, 2020

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Viable Monkeypox virus in the environment of a patient room

We conducted a prospective environmental surveillance study to investigate the air, surface, dust... more We conducted a prospective environmental surveillance study to investigate the air, surface, dust and water contamination of a room occupied by a patient infected with Monkeypox virus (MPXV) at various stages of his illness. The patient tested positive for MPXV from a throat swab and skin lesions. Environmental sampling was conducted in a negative pressure room with 12 unidirectional HEPA air changes per hour and daily cleaning of the surfaces. A total of 179 environmental samples were collected on days 7, 8, 13, and 21 of his illness. Air, surface, and dust contamination was highest during the first eight days of the illness, with a gradual decline to the lowest contamination level by day 21. Viable MPXV was isolated from surfaces and dust samples and no viable virus was isolated from the air and water samples.SynopsisInadequate research prevail on the mode of transmission for monkeypox virus. This study reports the findings of viable monkeypox virus from the patient environment, h...

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Research paper thumbnail of Differential aerosol shedding of SARS-CoV-2 Delta and Omicron variants during respiratory activities

Data on the viral loads in respiratory aerosols from patients infected with Delta and Omicron var... more Data on the viral loads in respiratory aerosols from patients infected with Delta and Omicron variants are limited. In this study, we used an exhaled breath bioaerosol collector to collect aerosol samples in coarse (> 5µm) and fine (≤ 5µm) fractions from COVID-19 patients infected with these VOCs while doing various respiratory activities. Samples were tested via SARS-CoV-2 RT-qPCR and virus culture. Nine patients (4 Delta and 5 Omicron) were included. Viral RNA was detectable in seven participants, with greater viral loads in fine aerosols. Notably SARS-CoV-2 RNA was consistently detectable in respiratory samples of all Omicron patients despite them being fully vaccinated and mostly asymptomatic in contrast with Delta patients. Singing and talking without mask generated the greatest viral loads underscoring the transmission potential of SARS-CoV-2 and its variants via respiratory aerosols. The more consistent detection of viral RNA in Omicron-infected patients may account for it...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of System Evaluation in the Tropics

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Viral Load of SARS-CoV-2 in Respiratory Aerosols Emitted by COVID-19 Patients while Breathing, Talking, and Singing

BackgroundMultiple SARS-CoV-2 superspreading events suggest that aerosols play an important role ... more BackgroundMultiple SARS-CoV-2 superspreading events suggest that aerosols play an important role in driving the COVID-19 pandemic. However, the detailed roles of coarse (>5μm) and fine (≤5μm) respiratory aerosols produced when breathing, talking, and singing are not well-understood.MethodsUsing a G-II exhaled breath collector, we measured viral RNA in coarse and fine respiratory aerosols emitted by COVID-19 patients during 30 minutes of breathing, 15 minutes of talking, and 15 minutes of singing.ResultsAmong the 22 study participants, 13 (59%) emitted detectable levels of SARS-CoV-2 RNA in respiratory aerosols, including 3 asymptomatic patients and 1 presymptomatic patient. Viral loads ranged from 63–5,821 N gene copies per expiratory activity per patient. Patients earlier in illness were more likely to emit detectable RNA, and loads differed significantly between breathing, talking, and singing. The largest proportion of SARS-CoV-2 RNA copies was emitted by singing (53%), follow...

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Characterizing exhaled aerosol droplets during influenza A and B infections, and viral hemagglutinin phylogenetic analyses in a university cohort

International Journal of Infectious Diseases, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Mitigating particulate matter exposure in naturally ventilated buildings during haze episodes

Building and Environment, 2018

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Associations of Plasticized Wall and Floor Coverings With Asthma and Allergies Among Tropical Preschool Children

Epidemiology, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Concentration and emission rates of indoor VOCS-A comparative study between Singapore and European office buildings

Note: EPFL Reference LESO-PB-CONF-2003-002 Record created on 2005-01-12, modified on 2016-08-08

Bookmarks Related papers MentionsView impact

Research paper thumbnail of The greening of Singapore's national estate

Habitat International, 1997

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Emission modelling and validation of VOCs' source strengths in air-conditioned office premises

Environment International, 2004

Bookmarks Related papers MentionsView impact

Research paper thumbnail of BubbleZERO—Design, Construction and Operation of a Transportable Research Laboratory for Low Exergy Building System Evaluation in the Tropics

Energies, 2013

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Indoor air quality comparison of two air-conditioned zones served by the same air-handling unit

Building and Environment, 2002

Most indoor air quality (IAQ) investigations take an air handling unit (AHU) - based zone as the ... more Most indoor air quality (IAQ) investigations take an air handling unit (AHU) - based zone as the basic unit for investigation from the logical viewpoint that the AHU constitutes the mechanism for mixing and (cross-) transportation of pollutants within the zone. If there is very good air-mixing, as indicated by a high air exchange effectiveness, the single zone approach may

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A study of perceived air quality and sick building syndrome in a field environment chamber served by displacement ventilation system in the tropics

Building and Environment, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of A comparative study of VOCs in Singapore and European office buildings

Building and Environment, 2006

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Interaction of convective flow generated by human body with room ventilation flow: impact on transport of pollution to the breathing zone

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Call-centre operator performance with new and used filters at two outdoor air supply rates

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Thermal effect of temperature gradient in a field environment chamber served by displacement ventilation system in the tropics

Building and Environment, 2007

Bookmarks Related papers MentionsView impact

Research paper thumbnail of Indoor air quality and energy performance of air-conditioned office buildings in Singapore

Indoor Air, Nov 24, 2003

Bookmarks Related papers MentionsView impact

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