Yale researchers say your coworker that smokes is harming you more than you know

It’s surreal to consider within a modern context, but in decades past smoking was allowed literally anywhere. Airplanes, restaurants, college classrooms; anywhere you can imagine, rest assured it was filled with cigarette smoke on a daily basis. We all know much more today about just how harmful cigarettes can be, not only for the smoker but also among those unlucky enough to be exposed to second-hand smoke. 

What about third-hand smoke, though? It’s not a widely known term at all, but researchers from Yale University have come to a number of troubling conclusions. Essentially, they’ve found that third-hand smoke is being spread extensively into indoor non-smoking environments by attaching itself to people. So, let’s say you’re staying at a hotel. You are probably being exposed to hazardous chemicals from third-hand smoke even though no one has ever actually smoked in that room. 

All it takes for third-hand smoke to spread is for someone to simply walk by another person smoking a cigarette. Those chemicals attach themselves to the passer-by and then hop off once that person enters a building. So pretty much everyone who has ever walked down a city street has subsequently spread third-hand smoke for the rest of that day.

Third-hand smoke, by definition, is considered “residual contamination” left behind from cigarette smoke that adheres itself to walls and other physical items. We’ve all experienced it. Ever hopped in a car where your friend had smoked a cigarette a few hours before and immediately been hit with the unmistakable smell of cigarettes? That’s third-hand smoke.

While the idea of third-hand smoke alone isn’t a new concept, the discovery that it can be spread via people who never smoked in the first place is the real story here. The chemicals in third-hand smoke are, of course, not as unhealthy as flat out first or second-hand cigarette smoke, but you can probably imagine it isn’t exactly healthy either.

“In real-world conditions, we see concentrated emissions of hazardous gases coming from groups of people who were previously exposed to tobacco smoke as they enter a non-smoking location with strict regulations against indoor smoking,” explains Yale researcher Drew Gentner, an associate professor of chemical & environmental engineering, in a press release. “People are substantial carriers of third-hand smoke contaminants to other environments. So, the idea that someone is protected from the potential health effects of cigarette smoke because they’re not directly exposed to second-hand smoke is not the case.”

Whether or not someone chooses to smoke is entirely their decision, and in a role reversal to the free smoking days of old, most smokers nowadays are usually asked to indulge in specific corners of restaurants or take their habit outside. Unfortunately, it appears that even these measures really aren’t enough to protect the rest of us.

To make these groundbreaking discoveries, the team at Yale set up a series of highly sensitive and advanced analytical instruments at a local movie theater. That equipment was then used to track and assess thousands of microscopic compounds (gases, particles) present in the theater over the course of a full week.

A large assortment of volatile and unhealthy organic compounds associated with tobacco smoke increased dramatically at various times over the observation period when certain sets of moviegoers arrived in the theater. These spikes in harmful compounds were much more prominent during R-rated movies, and at their lowest during G-rated movies. Now, obviously people going to see an R-rated movie are more likely to smoke themselves, but adults are also more likely to be exposed to cigarette smoke in general; walking city streets, visiting bars, restaurants, etc.

Moreover, further analysis of the compounds revealed that they were from aged cigarette smoke. That last observation is an important one, as it indicates most of the harmful chemicals being carried into the theater weren’t from cigarettes that had just been smoked outside the building.

“Despite regulations preventing people from smoking indoors, near entryways, and near air intakes, hazardous chemicals from cigarette smoke are still making their way indoors,” says lead author Roger Sheu, a Ph.D. student in Gentner’s lab.

You may be inclined to write off these findings as inconsequential. After all, how dangerous could old, third-hand smoke really be? According to the study’s authors, actually pretty harmful. The gas emissions detected in the theater were roughly the equivalent of being exposed to 1-10 cigarettes worth of second-hand smoke within one hour.

The hazardous emissions were most prominent when audiences first arrived, dissipating slowly over the course of the movie. However, even after audiences left the theater, trace amounts of the harmful chemicals lingered around for days. These compounds are able to stick around for such a long time because they don’t just stay in the air, but attach themselves to physical objects. In this case, the chemicals adhered themselves to the theater chairs and walls.

Reading this may make you want to skip your next scheduled movie night, but the research team made a point to note that the theater used for this study was actually quite modern, spacious, and well-ventilated. These attributes probably mitigated at least some of the third-hand smoke’s effects. It’s other places, such as cramped public transit spaces, crowded bars, or poorly ventilated office buildings, that likely represent the biggest third-hand smoke health hazards.

These findings are troubling, no doubt, but it’s also important not to overreact. The next time you catch the slightest whiff of cigarette smoke at the office, open a window. That being said, there’s no point in living in fear of every unseen hazard the world has to offer. If we all fell victim to that line of thought, no one would ever leave their house.

The full study can be found here, published in Science Advances.