Can You Get COVID-19 From Secondhand Smoke?

Since COVID-19 is spread through droplets in the breath, smokers may be putting others at risk when they blow the smoke out.

To understand COVID-19, it's important to understand how it's spread. When we breathe, tiny droplets of varying sizes are released during exhalation. One way COVID-19 is spread is when the droplets we exhale contain SARS-CoV-2, the virus that causes COVID-19, and other people breathe them in. And according to the Centers for Disease Prevention and Control (CDC), it's not just breathing that can pass the virus on. It's also coughing, sneezing, talking, singing, and during exercise (because you're breathing heavier).

But what about smoking? If the person standing next to you is exhaling cigarette smoke in your direction, could breathing in the secondhand smoke give you COVID-19?

In a word—possibly. While there are very few studies looking directly at secondhand smoke and the spread of COVID-19, the same droplets people spray when they're coughing, sneezing, or talking are exhaled when they're smoking (and vaping).

While experts were unsure at the beginning of the pandemic regarding the aerosolization of COVID-19 droplets, studies do suggest that some of the smaller droplets can become aerosolized, which means they could possibly linger in the air for hours. For example, one 2021 study published in the journal Environmental Research suggested that "aerosols are an important transport route for SARS-CoV-2, as aerosols particles can contain the infectious SARS-CoV-2, and remain suspended in the air for hours, which may be up to several meters transported from the source."

And the CDC does state in one of its documents that one of the ways COVID-19 can be transmitted is by "inhalation of very fine respiratory droplets and aerosol particles".

This means you may be able to contract COVID-19 through secondhand smoke if the person smoking is infected with the virus. "It's plausible to presume that a plume of smoke, which is comprised of respiratory droplets, can result in COVID-19 transmission," Osita Onugha, MD, thoracic surgeon and assistant professor of thoracic surgery at the John Wayne Cancer Institute in Santa Monica, California, told Health.

There's also one crucial difference between exhaling breath and exhaling smoke—you can breathe through a face covering, but you can't smoke through one.

"Since the novel coronavirus is spread via direct person-to-person contact, activities that include being in close contact (less than six feet) without a mask on should be avoided, which includes secondhand smoke," Julie Lyou, MD, MPH, a pulmonologist with St. Jude Medical Center in Fullerton, California, told Health. "The act of smoking requires the person to take off the mask, so this is considered a high-risk environment for anyone in the vicinity."

Although there's no evidence that smoke makes the virus travel farther, Dr. Onugha said there's no safe distance that can be recommended to protect someone when standing around cigarette smokers and advised wearing a face covering to minimize the risk of transmission.

Concerning COVID-19, smokers themselves may be at a greater risk. In a 2021 observational study published in the British Medical Association journal Thorax, researchers found that smokers were at higher risk of severe COVID-19, including higher rates of hospitalizations and death.

The research appears to be mixed, though. In a 2021 study published in the European Journal of Integrative Medicine, researchers suggested that while smoking, in general, increased the risk of severe COVID-19, it's the former smokers who were at the highest risk. Another study published in the International Journal of Epidemiology echoed these findings.

But don't go out and start lighting up just yet. In both studies, smokers were still at a higher risk of severe COVID-19 compared to those who had never smoked. In the latter study, all-cause mortality in the smoking group was also higher compared to those who had never smoked (all-cause mortality is the death rate for all causes of death for a population within a certain time period)—because smoking is a well-known risk factor for disease and death in general. And both the CDC and World Health Organization (WHO) caution that smoking is, indeed, a risk factor for severe COVID-19.

Regardless of COVID-19, non-smokers should steer clear of secondhand smoke anyway. "Studies have shown associations of secondhand smoke with increased risk of lung cancer and cardiovascular disease, including heart attack and stroke," said Dr. Lyou. "Even short-term exposure to cigarette smoke can worsen pre-existing lung conditions, such as asthma and COPD."

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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