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CDC Recognizes COVID-19 Can Be Airborne: Here's What That Means

People in crowded terminal wearing face masks

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Key Takeaways

  • The Centers for Disease Control and Prevention (CDC) is acknowledging COVID-19 can be spread through airborne transmission.
  • The World Health Organization has recognized airborne transmission as a possibility since July.
  • The CDC says larger respiratory droplets are more likely to spread COVID-19 than the small aerosols spread via airborne transmission.
  • Wearing a mask—especially indoors, when the space is poorly ventilated—is the best way to protect against airborne transmission.

Daily surges in coronavirus (COVID-19) cases across the United States have resulted in the continued push for preventative measures—like social distancing, wearing masks, and regular hand washing—from major health organizations, like the Centers for Disease Control and Prevention (CDC). But through an increase in research and methods like contact tracing, experts continue to learn more information about how COVID-19 spreads. The latest? Airborne transmission. 

"CDC continues to believe, based on current science, that people are more likely to become infected the longer and closer they are to a person with COVID-19," the agency said in a statement on Monday.

“Today’s update acknowledges the existence of some published reports showing limited, uncommon circumstances where people with COVID-19 infected others who were more than 6 feet away or shortly after the COVID-19-positive person left an area. In these instances, transmission occurred in poorly ventilated and enclosed spaces that often involved activities that caused heavier breathing, like singing or exercise. Such environments and activities may contribute to the buildup of virus-carrying particles.”

The CDC isn’t the first to declare airborne transmission as a means for spreading COVID-19.

In early July, 239 scientists in 32 countries authored an open letter urging the World Health Organization (WHO) to add airborne transmission to its list of how COVID-19 is spread. According to the scientists behind the letter, airborne transmission was "the only plausible explanation" for COVID-19 outbreaks that occurred as a result of large gatherings or “super-spreading events,” even when people had no close contact with one another.

At the time, WHO already included direct, indirect (through contaminated objects or surfaces), and/or close contact with infected people via mouth and nose secretions—think saliva, coughing, sneezing, speaking, or singing—in its list of ways in which COVID-19 is commonly transmitted. But on July 9, the organization revised its guidelines to include aerosol, or airborne, transmission as a way in which COVID-19 can spread.

“In these events, short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out,” the news release said.

What Exactly Is Airborne Transmission?

Well, it’s pretty much what it sounds like. A person might become infected with COVID-19 through an aerosol—a small respiratory particle that lingers in the air after a person coughs, sneezes, talks, or even sings. This is different than respiratory droplets, says Erika Schwartz, MD, a New York-based preventive medicine specialist, which result from a person sneezing or coughing, but are heavy and fall to the ground quickly, and within six feet from where they were expelled. 

“Respiratory illnesses are most commonly transmitted through droplets exhaled (i.e. breathed out) by an infected person that most likely can reach within a range of around six feet,” Schwartz, who is also the author of Don’t Let Your Doctor Kill You, tells Verywell. “Airborne transmission reaches farther than six feet and typically occurs in poorly ventilated areas.”

For a droplet to become airborne, Schwartz says, it all depends on a droplet’s size and projection. That can mean the difference between an infected person coughing, sneezing, yelling, singing, talking, or whispering, she says, adding that “larger droplets occur when they leave the infected person’s airway and progressively get smaller as they fall through the air."

Put simply, Schwartz says: “[Aerosol] particles are transmitted through the air, they are small, reach farther than six feet, and stay suspended in the air longer—for a few minutes or [even] hours.”

In addition to COVID-19, tuberculosis, measles, and chickenpox are also spread through airborne transmission, according to the CDC.

What This Means For You

The CDC's recognition of airborne transmission only emphasizes the importance of precautionary COVID-19 measures you may already be taking. Wear a mask to protect yourself. Inhaling SARS-CoV-2 particles is your biggest risk of contracting the virus.

How Do I Prevent Airborne Transmission?

All of your usual COVID-19 prevention techniques should be at play in order to avoid airborne transmission. This includes wearing a mask, maintaining a social distance of six feet or more from other people, regular hand washing, and routinely disinfecting frequently touched surfaces, like doorknobs, countertops, phones, keys, toilets, tables, and light switches.

You’ll also want to avoid crowded indoor spaces and those with poor ventilation, says Mary Clifton, MD, an internal medicine physician at Boomer Naturals, which may become increasingly difficult as winter approaches and people spend more time indoors.

“While it is still important to keep your hands clean and away from your face, and keep surfaces clean, your biggest risk is the inhalation of these particles from the air that can adhere to the back of your throat [and cause COVID-19 infection],” she tells Verywell.

Schwartz agrees, adding that droplet transmission can become airborne transmission if the droplets are small.

"In spaces that are not properly ventilated, especially in enclosed spaces, airborne transmission is more common, which means choosing not to wear a mask in a closed space could still result in COVID-19 transmission even if social distancing is maintained," Schwartz says.

Yes, that means wearing a mask indoors when the area is poorly ventilated, which might include hospitals, churches, offices, restaurants, or public bathrooms. Schwartz even suggests changing your clothes when you come home from work or after using mass transit or traveling and taking a shower before engaging with other members of your household. 

“Above all, stay home if you do not feel well,” she says. “Mutual respect and care for each other is the only way to prevent the spread of COVID and will help us get back our lives."

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  1. Centers for Disease Control and Prevention. CDC updates “How COVID is spread” webpage. Updated October 5, 2020.

  2. Morawska L, Milton DK. It is time to address airborne transmission of coronavirus disease 2019 (COVID-19)Clinical Infectious Diseases. ciaa939. July 6 2020. doi:10.1093/cid/ciaa939

  3. World Health Organization. Transmission of SARS-CoV-2: implications for infection prevention precautions. Updated July 9, 2020.

  4. Centers for Disease Control and Prevention. How COVID-19 spreads. Updated October 5, 2020.