TY - JOUR
T1 - Assessing impact of ventilation on airborne transmission of SARS-CoV-2
T2 - A cross-sectional analysis of naturally ventilated healthcare settings in Bangladesh
AU - Styczynski, Ashley
AU - Hemlock, Caitlin
AU - Hoque, Kazi Injamamul
AU - Verma, Renu
AU - Leboa, Chris
AU - Bhuiyan, Md. Omar Faruk
AU - Nag, Auddithio
AU - Harun, Md. Golam Dostogir
AU - Amin, Mohammed Badrul
AU - Andrews, Jason R.
N1 - Funding Information: 3Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh Acknowledgements We would like to thank Aninda Rahman, Communicable Disease Control Program, Directorate General of Health Services (DGHS), for his facilitation to conduct this research. We would also like to thank Pedro M. de Oliveira, Savvas Gkantonas and Epaminondas Mastorakos from the University of Cambridge, Department of Engineering for sharing thoughtful insights around airborne transmission risk modeling. Additionally, we appreciate the cooperation of the hospitals in Dhaka who allowed us to collect these measurements. Contributors AS contributed to the research conception and design and manuscript writing; CH performed data analysis and contributed to research design and manuscript writing; RV participated in the research design, data analysis and interpretation, and manuscript writing; KIH contributed to the research design, data collection, and data analysis; CL participated in the research design, data analysis, and manuscript writing; AN contributed to research design and data collection; MOFB participated in data collection; MGDH contributed to research design and dissemination of findings for public health practice; MBA contributed to the research conception and design and interpretation of results; JRA contributed to research conception and design, interpretation of findings, and manuscript writing. As the guarantor, AS accepts full responsibility for the work and the conduct of the study, had access to the data, and controlled the decision to publish. Funding This study was supported by an anonymous donation to the Stanford University School of Medicine. icddr,b acknowledges with gratitude the funding support of Stanford University School of Medicine. icddr,b is also thankful to the following donors: the governments of Bangladesh, Canada, Sweden and UK for providing core/ unrestricted support. The donors had no role in data analysis, interpretation or decision to publish the findings. Competing interests None declared. Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research. Patient consent for publication Not applicable. Ethics approval The current study was approved by the research and ethics review committees at icddr,b (number PR-20063). Because the study did not involve a human subjects component, it was considered not to require IRB approval at Stanford University or University of California Berkeley. Publisher Copyright: © 2022 BMJ Publishing Group. All rights reserved.
PY - 2022/4/15
Y1 - 2022/4/15
N2 - Objectives To evaluate the risk of exposure to SARS-CoV-2 in naturally ventilated hospital settings by measuring parameters of ventilation and comparing these findings with results of bioaerosol sampling. Study design Cross-sectional study. Study setting and study sample The study sample included nine hospitals in Dhaka, Bangladesh. Ventilation characteristics and air samples were collected from 86 healthcare spaces during October 2020 to February 2021. Primary outcome Risk of cumulative SARS-CoV-2 infection by type of healthcare area. Secondary outcomes Ventilation rates by healthcare space; risk of airborne detection of SARS-CoV-2 across healthcare spaces; impact of room characteristics on absolute ventilation; SARS-CoV-2 detection by naturally ventilated versus mechanically ventilated spaces. Results The majority (78.7%) of naturally ventilated patient care rooms had ventilation rates that fell short of the recommended ventilation rate of 60 L/s/p. Using a modified Wells-Riley equation and local COVID-19 case numbers, we found that over a 40-hour exposure period, outpatient departments posed the highest median risk for infection (7.7%). SARS-CoV-2 RNA was most frequently detected in air samples from non-COVID wards (50.0%) followed by outpatient departments (42.9%). Naturally ventilated spaces (22.6%) had higher rates of SARS-CoV-2 detection compared with mechanically ventilated spaces (8.3%), though the difference was not statistically significant (p=0.128). In multivariable linear regression with calculated elasticity, open door area and cross-ventilation were found to have a significant impact on ventilation. Conclusion Our findings provide evidence that naturally ventilated healthcare settings may pose a high risk for exposure to SARS-CoV-2, particularly among non-COVID-designated spaces, but improving parameters of ventilation can mitigate this risk.
AB - Objectives To evaluate the risk of exposure to SARS-CoV-2 in naturally ventilated hospital settings by measuring parameters of ventilation and comparing these findings with results of bioaerosol sampling. Study design Cross-sectional study. Study setting and study sample The study sample included nine hospitals in Dhaka, Bangladesh. Ventilation characteristics and air samples were collected from 86 healthcare spaces during October 2020 to February 2021. Primary outcome Risk of cumulative SARS-CoV-2 infection by type of healthcare area. Secondary outcomes Ventilation rates by healthcare space; risk of airborne detection of SARS-CoV-2 across healthcare spaces; impact of room characteristics on absolute ventilation; SARS-CoV-2 detection by naturally ventilated versus mechanically ventilated spaces. Results The majority (78.7%) of naturally ventilated patient care rooms had ventilation rates that fell short of the recommended ventilation rate of 60 L/s/p. Using a modified Wells-Riley equation and local COVID-19 case numbers, we found that over a 40-hour exposure period, outpatient departments posed the highest median risk for infection (7.7%). SARS-CoV-2 RNA was most frequently detected in air samples from non-COVID wards (50.0%) followed by outpatient departments (42.9%). Naturally ventilated spaces (22.6%) had higher rates of SARS-CoV-2 detection compared with mechanically ventilated spaces (8.3%), though the difference was not statistically significant (p=0.128). In multivariable linear regression with calculated elasticity, open door area and cross-ventilation were found to have a significant impact on ventilation. Conclusion Our findings provide evidence that naturally ventilated healthcare settings may pose a high risk for exposure to SARS-CoV-2, particularly among non-COVID-designated spaces, but improving parameters of ventilation can mitigate this risk.
KW - Airborne transmission
KW - COVID-19
KW - SARS-CoV-2
KW - healthcare
KW - hospital
KW - nosocomial infection
KW - ventilation
UR - http://www.scopus.com/inward/record.url?scp=85128488274&partnerID=8YFLogxK
U2 - https://doi.org/10.1136/bmjopen-2021-055206
DO - https://doi.org/10.1136/bmjopen-2021-055206
M3 - Article
C2 - 35428628
SN - 2044-6055
VL - 12
JO - BMJ Open
JF - BMJ Open
IS - 4
M1 - e055206
ER -