Leading Experts Call for Immediate Action to Address Inhalation Exposure to Prevent COVID-19 Infections and Deaths

Letter encourages federal agencies to update guidance to acknowledge and mitigate aerosol transmission

Leading scientific and medical experts, including researchers from the University of California San Diego, are calling upon the Biden Administration to take immediate action to address inhalation exposure to the SARS-CoV-2 virus as a cornerstone of the COVID-19 pandemic response.

In a letter to the Biden administration’s top officials heading the response, the experts from the fields of aerosol science, occupational health and infectious disease urge the Centers for Disease Control and Prevention (CDC), the Occupational Safety and Health Administration (OSHA), and other government agencies to fully recognize inhalation exposure as the primary way the virus spreads and to take immediate action to protect against this source of exposure. Signatories from UC San Diego include Kimberly Prather, distinguished professor of atmospheric chemistry with Scripps Institution of Oceanography, and Robert T. Schooley, infectious disease specialist and professor in the Department of Medicine at UC San Diego School of Medicine.

The letter commends the administration COVID-19 plan to ramp up vaccine availability and calls for widespread use of masks, stronger measures to protect workers and the public. The experts emphasize, however, that to be successful the plan must also strengthen measures to address inhalation exposure to the virus.

“Our letter focuses on the importance of acknowledging the fact that aerosol transmission is playing a major role in spreading SARS-CoV-2,” said Prather, who also co-directs the National Science Foundation-funded Center for Aerosol Impacts on Chemistry of the Environment based at Scripps Oceanography. “We now know from evidence that infectious aerosols, produced simply by breathing and speaking, float in air for hours and can accumulate indoors in poorly ventilated spaces. Our letter encourages CDC and other federal agencies to provide clear guidance on how to best protect against inhalation exposure to aerosols so we can reopen, and safely keep open, schools and businesses. This includes taking steps to test and improve ventilation and filtration to clean the air that people share in indoor spaces.”

The experts assert that the scientific evidence is clear: Inhalation of small aerosol particles is one of the primary sources of exposure and transmission of the SARS-CoV-2 virus. CDC guidelines and recommendations are out of date and do not fully recognize inhalation exposure or include the necessary control measures to protect the public or workers from this mode of transmission. Inadequately protective recommendations particularly impact people of color, many of whom work on the front lines and who remain at the greatest risk of COVID-19 exposure, infection, and death.

 “CDC guidance and recommendations do not include the control measures necessary for protecting the public and workers from inhalation exposure to SARS-CoV-2,” write the letter’s authors. “The failure to address inhalation exposure to SARS-CoV-2 continues to put workers and the public at serious risk of infection. People of color, many of whom work on the front lines in essential jobs, have suffered – and continue to suffer – the greatest impacts of the COVID-19 pandemic.”

The emergence of more transmissible virus variants makes strong action to control the virus even more urgent: “While COVID-19 infections and deaths have started to decline in recent weeks, they remain at a very high level and, unless strengthened precautionary measures are implemented, the new variants will likely bring an explosion in new infections.”

To address and limit transmission via inhalation exposure, prevent COVID infections and deaths, and bring the pandemic under control, the experts call upon the Biden administration to take immediate actions:

  • CDC must make clear to the public that inhalation exposure through small aerosols is a principal way the virus spreads and update its policy and guidelines to address small particle inhalation in public and workplace settings, and must develop guidelines for better quality face coverings for the public.

  • CDC and OSHA must issue recommendations and requirements for the use of NIOSH-approved respirators such as N95 filtering facepiece respirators - for all healthcare workers and other workers at high risk, including those in meat and poultry processing facilities, corrections facilities and transit operations. A year into this pandemic we must provide appropriate respiratory protection to all workers who need it.

  • OSHA must issue an emergency workplace standard on COVID-19 that requires an assessment of inhalation risk, adoption of controls including enhanced ventilation, physical distancing, effective respiratory protection for workers in high-risk jobs, and high-quality barrier face coverings and masks for other workers exposed to the virus on the job.

  • The federal government must use the Defense Production Act to ramp up production of respirators and high-quality barrier face coverings.

"This letter also encourages the federal government to implement the Defense Protection Act to ramp up production of NIOSH-certified respirators and ASTM-compliant barrier face coverings that better protect the public as well as high risk workers in the workplace against inhalation of aerosols," added Prather.

List of scientific and medical expert signatories:

  • Rick Bright, PhD, Former Director of BARDA, Dept of Health and Human Services
  • Lisa M. Brosseau, ScD, CIH, Professor (retired), Research Consultant, Center for Infectious Disease Research and Policy (CIDRAP), University of Minnesota
  • Lynn R. Goldman, MD, MS, MPH, Michael and Lori Milken Dean and Professor of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University
  • Céline Gounder, MD, ScM, Clinical Assistant Professor, Department of Medicine, NYU Grossman School of Medicine & Bellevue Hospital Center
  • Jose-Luis Jimenez, PhD, University of Colorado at Boulder
  • Yoshihiro Kawaoka, DVM, PhD, Professor, University of Wisconsin-Madison School of Veterinary Medicine and University of Tokyo
  • Linsey Marr, PhD, Charles P. Lunsford Professor, Department of Civil Engineering, Virginia Tech
  • David Michaels, PhD, MPH, Professor, Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University
  • Donald K. Milton, MD, DrPH, Professor of Environmental Health, School of Public Health and Professor, Internal Medicine, University of Maryland School of Medicine, University of Maryland
  • Michael Osterholm, PhD, MPH, Regents Professor, McKnight Presidential Endowed Chair in Public Health and Director, Center for Infectious Disease Research and Policy (CIDRAP), University of Minnesota
  • Kimberly Prather, PhD, Distinguished Chair in Atmospheric Chemistry and Director, NSF Center for Aerosol Impacts on Chemistry of the Environment (CAICE), Scripps Institution of Oceanography, University of California San Diego
  • Robert T. Schooley, MD, Professor of Medicine, Division of Infectious Diseases and Global Public Health and Co-Director, Center for Innovative Phage Applications and Therapeutics, University of California San Diego
  • Peg Seminario, MS, Safety and Health Director (retired), AFL-CIO

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