Dispelling the Myth: Marijuana Smoke is Not Safer Than Cigarette Smoke, According to American Beliefs

The majority of Americans believe inhaling marijuana smoke is safer than inhaling tobacco smoke, a new study shows.

The most recent National Survey on Drug Use and Health found nearly 20% of Americans aged 12 or older had used marijuana at least once in the past year, whether by smoking, vaping, or consuming edibles. Among people aged 18–25, more than a third had used marijuana in the past year.

While marijuana has grown in legality over recent years, the effects of inhaling marijuana smoke are still largely unstudied. Meanwhile, there are multiple bodies of research demonstrating the harmful effects of inhaling tobacco smoke, from lung cancer to emphysema.

Perhaps it is a longer history of research that makes tobacco smoke seem more harmful than marijuana smoke.

The new study showed there appears to be a disconnect between how people perceive marijuana smoke to impact their health and how it actually does.

“I’m sure there are differences between different types of smoke, and differences in the exact way they impact the lungs, but I don’t think we have any evidence that inhaling smoke is OK for our lungs,” Beth Cohen, MD, a professor of Medicine at UCSF who co-led the new research told Health.

“Smoke is smoke, and smoke is bad for your health,” she said

To understand the public perception of marijuana smoke, Cohen and her team surveyed more than 5,000 adults living in the United States.

They asked people to report their view of the health impacts of smoking tobacco every day compared to daily cannabis smoking. This included both the effects of first- and second-hand smoke.

The researchers found that people’s perceptions of the health effects of inhaling marijuana smoke are changing, even compared to just a few years ago.

In 2021, 44% of adults surveyed believed smoking marijuana every day is safer than smoking tobacco every day, compared to about 37% in 2017.

The same trend was seen in perceptions of secondhand smoke.

In 2017, about 35% of people believed secondhand cannabis smoke to be safer than secondhand cigarette smoke, compared to about 40% in 2021.

Cohen explained this perception as likely due to the fact that cannabis is becoming more widely accepted, while tobacco users are being met with more restrictions.

“Cannabis has this increasing presence that normalizes it. People perceive that as, ‘This is something I’m seeing more frequently and it’s now legal for me to use, so it must be safe,” she said.

Although cannabis smoke does carry health consequences, differences in how frequently a person is inhaling smoke likely play a big role in how the smoke—whether it’s from cannabis or tobacco—impacts their health.

While people who smoke tobacco often do so multiple times a day for years on end, people who smoke cannabis usually don’t do so as frequently, said Panagis Galiatsatos, MD, an associate professor of medicine and director of the Tobacco Treatment Clinic at Johns Hopkins Medicine. 

“This difference in usage is a significant factor in why tobacco, which is typically consumed extensively throughout the day and accumulating its harms over many years, has so many health risks associated with it,” Galiatsatos told Health. 

Because marijuana is typically smoked less frequently than tobacco, the negative impacts it does have are likely not as significant as tobacco.

Still, “I don’t think there’s really convincing data on this idea that cannabis smoke is hugely different and safer, at least from a chemical perspective,” said Cohen.

The legality of cannabis has blocked researchers from being able to conduct quality epidemiological studies on people who smoke cannabis, as they have been able to do with tobacco smokers.

“It’s hard to show long-term damage of exposure from such products in laboratory studies,” said Galiatsatos. “Tobacco’s link to cancer was proven by epidemiology studies following veterans over decades, who’d had autopsies when they died.”

Restrictions around cannabis have kept similar public health studies on marijuana smoke from occurring and have led to under-reporting among marijuana smokers.

“The research that has been done so far on long-term effects is inadequate,” said Cohen, who noted that chemically speaking, pure tobacco smoke contains much of the same particles that marijuana smoke does, even if the added chemicals present in many cigarettes aren’t added to cannabis.

Now that cannabis is legal in many states, companies hoping to sell it also have an incentive to push certain health claims, whether or not there is research to back them.

“We do know that there are harmful substances in cannabis smoke that are known to cause damage, so I would be very concerned about the health effects of smoking or vaping cannabis,” she said. “We really need to have better information to give people so they can make those informed decisions.”