We are pleased that in its updated Scientific Brief: SARS-CoV-2 Transmission CDC acknowledged today that transmission of the SARS-CoV-2 virus through inhalation of tiny aerosol particles is a primary route of exposure and that risk of inhaling the virus is greatest close to an infected person. This is an important and major step forward.
However, we are concerned that CDC’s accompanying document How COVID-19 Spreads is misleading, and potentially harmful.
In that document CDC says that breathing in small droplets and particles (i.e., aerosols) that contain the virus when people are far apart or have been in the same enclosed space for more than a few minutes is UNCOMMON (our emphasis). This will lead people to continue to think that maintaining distance is sufficient to prevent transmission.
We know that transmission at distances beyond 6 feet occurs because of superspreader events, careful studies of smaller outbreaks, and the physics of aerosols. It can easily happen indoors in a poorly ventilated environment, when people are not wearing masks.
There is clear consensus among aerosol scientists and epidemiologists that inhalation of small aerosol particles, including at distances of greater than six feet, is a major driver of the COVID-19 pandemic. To slow transmission and save lives, it is crucial that CDC update its guidance and recommendations to address and highlight the importance of improved ventilation and using NIOSH approved respirators, especially in indoor locations where the virus may accumulate in the air.
Moreover, OSHA must issue an Emergency Temporary Standard to control workplace exposures, including inhalation exposure, as soon as possible in order to protect workers and reopen the economy safely.
As CDC has made clear, vaccination alone will not stop this pandemic. Mitigation measures are also needed to limit exposures. We must control inhalation exposure of small aerosol particles to end this pandemic.
CDC must immediately update and strengthen its guidelines and recommendations to protect the public and workers for inhalation exposures to SARS-CoV-2.
More on the importance of addressing aerosol transmission and the steps needed to control exposures can be found in the letter several of us sent to federal COVID-19 leaders in February 2021.
David Michaels, PhD, MPH
Professor, Department of Environmental and Occupational Health
Milken Institute School of Public Health
The George Washington University
Former Assistant Secretary if Labor for OSHA (2009-2017)
Donald K. Milton, MD, DrPH
Professor, Institute for Applied Environmental Health
Department of Epidemiology and Biostatistics
University of Maryland School of Public Health
Linsey C. Marr, PhD
Professor, Civil and Environmental Engineering
Center for Emerging, Zoonotic, and Arthropod-Borne Pathogens
Lisa M Brosseau, ScD, CIH
Research Consultant, University of Minnesota, Center for Infectious Disease Research and Policy
Safety and Health Director, AFL-CIO (retired)
Kimberly A. Prather, Ph.D.
Director, NSF Center for Aerosol Impacts on Chemistry of the
Distinguished Chair in Atmospheric Chemistry
Scripps Institution of Oceanography
University of California, San Diego
Michael T. Osterholm, PhD, MPH
Regents Professor, McKnight Presidential Endowed Chair in Public Health
Director, Center for Infectious Disease Research and Policy
University of Minnesota