Was the tardiness of the U.S. Centers for Disease Control in accepting airborne transmission of COVID-19 a factor in a court ruling striking down a national mask mandate?

It's a question that the public might want to consider in the wake of U.S. District Judge Kathryn Kimball Mizelle's recent 59-page decision.

The Health Freedom Defense Fund Inc., Ana Carolina Daza, and Sarah Pope obtained a court order voiding the mask mandate for travel on planes and public transportation.

When the CDC issued its mask mandate on February 3, 2021, it stated that the spread of COVID-19 "occurs mainly through the transfer of 'respiratory droplets' from one person to another".

The CDC waited until May 7, 2021 before formally acknowledging that exposure to COVID-19 can occur through the inhalation of aerosol particles.

Mizelle, a Donald Trump-appointed judge, devoted a considerable amount of her ruling around the semantics of the word "sanitation measure" and whether this could be applied in law to the CDC's mask mandate.

The U.S. Public Health Service Administration does not define "sanitation", the judge noted.

"Put simply, sanitation as used in the PHSA could have referred to active measures to cleanse something or to preserve the cleanliness of something," Mizelle wrote. "While the latter definition would appear to cover the Mask Mandate, the former definition would preclude it."

She also criticized the CDC for falling short of the Administrative Procedure Act's public-notification requirements, even though the CDC cited the "good cause exception".

Mizelle contrasted the CDC's efforts with those of the Centers for Medicare and Medicaid Services when it mandated vaccinations for staff in healthcare facilities. In that instance, the agency provided nearly four pages of justification and 40 footnotes of supporting sources.

"The Supreme Court concluded that this extensive reasoning properly invoked the good cause exception," she wrote.

As early as September 21, 2020, the CDC's deputy director for infectious diseases acknowledged a possibility that COVID-19 could be transmitted via the airborne route. But this was not included in the justification for the mask mandate issued more than four months later. 

Mizelle's ruling striking down the mask mandate did not once mention the word "airborne" in connection with the virus. Instead, the decision is permeated with what aerosol scientists disparagingly describe as "droplet dogma".

The judge noted that "sanitation" is limited to cleaning measures.

"As a result, the Mask Mandate is best understood not as sanitation, but as an exercise of the CDC's power to conditionally release individuals to travel despite concerns that they may spread a communicable disease (and to detain or partially quarantine those who refuse)," Mizelle wrote. "But the power to conditionally release and detain is ordinarily limited to individuals entering the United States from a foreign country."

She also said that it could only be done to those travelling between states if they "can be reasonably believed to be infected."

The mask mandate, in her view, complied with neither of these requirements.

"It does not explain why all masks—homemade and medical-grade—are sufficient," the judge added. "Nor does it require 'social distancing [or] frequent handwashing,' despite finding these effective strategies for reducing COVID-19 transmission. In sum, irrespective of whether the CDC made a good or accurate decision, it needed to explain why it acted as it did."

One of the early papers identifying airborne transmission as the dominant route for the spread of COVID-19 was published in the peer-reviewed Proceedings of the National Academy of Sciences on June 11, 2020.

That was nearly six months before the CDC cited droplet dogma in justifying its mask mandate on planes and public transportation.

"Our analysis reveals that the difference with and without mandated face covering represents the determinant in shaping the trends of the pandemic," wrote researchers Renyi Zhang, Yixin Li, Annie L. Zhang, and Mario J. Molina. "This protective measure significantly reduces the number of infections."

They came to this conclusion after analyzing the trend of infections and mitigation measures employed in New York City, Italy, and the Chinese city of Wuhan from January 23 to May 9, 2020.

They argued that masks reduced the number of infections in Italy by more than 78,000 from April 6 to May 9, 2020. Masking also resulted in 66,000 fewer infections in New York City from April 17 to May 9, 2020.

"Other mitigation measures, such as social distancing implemented in the United States, are insufficient by themselves in protecting the public," they stated. "We conclude that wearing of face masks in public corresponds to the most effective means to prevent interhuman transmission, and this inexpensive practice, in conjunction with simultaneous social distancing, quarantine, and contact tracing, represents the most likely fighting opportunity to stop the COVID-19 pandemic."

On July 8, 2020, Nature published an article documenting mounting evidence suggesting that the SARS-CoV-2 virus that causes COVID-19 is airborne.

This came after 239 clinicians, infectious-disease physicians, epidemiologists, engineers, and aerosol scientists published a commentary in Clinical Infectious Diseases.

They demanded that public-health officials acknowledge the "significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room scale)".

They added: "we are advocating for the use of preventive measures to mitigate this route of airborne transmission."

Last month, the White House formally recognized that the most common way that the virus is spread is "through tiny airborne particles of the virus hanging in indoor air for minutes or hours after an infected person has been there".