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High humidity leads to loss of infectious influenza virus from simulated coughs.

Authors
Noti-JD; Blachere-FM; McMillen-DM; Lindsley-WG; Kashon-ML; Slaughter-DR; Beezhold-DH
Source
PLoS One 2013 Feb; 8(2):e57485
NIOSHTIC No.
20042261
Abstract
Background: The role of relative humidity in the aerosol transmission of influenza was examined in a simulated examination room containing coughing and breathing manikins. Methods: Nebulized influenza was coughed into the examination room and Bioaerosol samplers collected size-fractionated aerosols (<1 micorM, 1-4 micorM, and >4 microM aerodynamic diameters) adjacent to the breathing manikin's mouth and also at other locations within the room. At constant temperature, the RH was varied from 7-73% and infectivity was assessed by the viral plaque assay. Results: Total virus collected for 60 minutes retained 70.6-77.3% infectivity at relative humidity = / <23% but only 14.6-22.2% at relative humidity = / >43%. Analysis of the individual aerosol fractions showed a similar loss in infectivity among the fractions. Time interval analysis showed that most of the loss in infectivity within each aerosol fraction occurred 0-15 minutes after coughing. Thereafter, losses in infectivity continued up to 5 hours after coughing, however, the rate of decline at 45% relative humidity was not statistically different than that at 20% regardless of the aerosol fraction analyzed. Conclusion: At low relative humidity, influenza retains maximal infectivity and inactivation of the virus at higher relative humidity occurs rapidly after coughing. Although virus carried on aerosol particles <4 microM have the potential for remaining suspended in air currents longer and traveling further distances than those on larger particles, their rapid inactivation at high humidity tempers this concern. Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus.
Keywords
Humidity; Aerosols; Infectious-diseases; Diseases; Disease-vectors; Biological-effects; Statistical-analysis; Viral-diseases
Contact
John D. Noti, PhD, HELD/NIOSH/CDC, 1095 Willowdale Road, M.S. 4020, Morgantown, WV 26505-2888
CODEN
POLNCL
Publication Date
20130201
Document Type
Journal Article
Email Address
ivr2@cdc.gov
Fiscal Year
2013
NTIS Accession No.
NTIS Price
Identifying No.
B20130321
Issue of Publication
2
ISSN
1932-6203
NIOSH Division
HELD
Priority Area
Healthcare and Social Assistance
Source Name
Public Library of Science One
State
WV
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