The anatomy and physiology of vapes: Pods

First of a two-part special report


The first time Paul* quit his tobacco habit was a decade ago. He had been smoking for around two years prior, but found that it was dragging him down. Paul was part of the varsity in school, and it was getting harder for him to keep up with all the cardio. And so, he just cut it off, largely unceremoniously―cold turkey, as it is more commonly referred to.

For the next handful of years, Paul lived smoke-free. But in 2015, while working for a boss who “smoked a lot,” he slipped. He says it opened up better channels of communication with his superior, something smoking is known to do.

Within about a year, Paul was already looking for ways to quit, “just for general health reasons,” he says. That’s when he started vaping.

At first, he was just taking hits off of his friends’ devices. He wasn’t picky about it, so whatever rig his friends had on them would do. This went on for a bit until in 2018, he was offered a popular vape brand at a discount, with a free custom engraving to boot. Paul decided then that it was time he bit the bullet and buy his own JUUL.

Technically speaking, JUULs fall under a broader class of vapes colloquially called pods, but because of its widespread success, the brand and the category have grown to be nearly synonymous. To the regular, casual consumer, JUUL is the face of this group, and the standard that other pod systems are held up against.

Small and slender, pods are the youngest members of a very diverse lineage of vaping devices. They are designed to be portable without giving up the core functionalities of a nicotine delivery system.

In large part, the appeal of pod vaporizers is in how low the barriers to entry are. For smokers seeking respite from burnt tobacco, jumping head first into the much more complicated tank-based vapes may be daunting. Having to learn all the different parts, models, juice flavors, and settings, on top of the maintenance these bulkier devices require, may be off-putting for someone whose habit only previously required them to light a stick and throw the butt away after.

In large part, the appeal of pod vaporizers is in how low the barriers to entry are.

Principles of design: What are pods made of?

Pod vaporizers are easy to use because of their simple, no-frills build. A single rechargeable battery makes up most of the body’s heft. By design, the battery is fixed onto a black, slightly larger console, that also houses a chipset. Presumably, this acts as the device’s brain, controlling and regulating its functions.

On one end of this console is a magnetized port, which lets the entire vaporizer clip onto a USB charging dock that comes with the purchase. On the other end are tiny metallic, spring-loaded prongs. These come into contact with small cartridges containing the e-juice, which are also referred to as pods. This is where the pod system of vaping devices gets its name from.

The console slots into a trim, aluminum, almost stylish casing. With the pod attached, the completed device looks like a slightly longer, much thinner flash drive.

An acrylic shell, shaped to fit into an opening on the vaping device, forms the bulk of the cartridge and acts as a sort of tank that can hold approximately a milliliter of e-juice. Different companies have come out with their own pod designs, and some variation in volume has been documented. Nevertheless, many cartridges still tend to share compatibility across different pod systems. The cartridges can come pre-filled and disposable, or refillable.

Inside the tank, the central shaft acts as a chimney through which the aerosolized liquid passes as the user inhales from the mouthpiece. At the bottom end of the pod is a pair of gold plates sandwiching a metal coil, which itself is wrapped around a wick. As with the tank volume, different brands use different materials for manufacturing. Some companies make wicks out of cotton, while others choose silica; coils, on the other hand, can be made from Kanthal (an alloy of iron, chromium, and aluminum) or nichrome (an alloy of nickel and chrome), among others.

Crucially, a portion of each gold plate needs to rest outside the acrylic casing. When the cartridge is locked into place, the plates press down on the console’s prongs, ready for action.

With the pod attached, the completed device looks like a slightly longer, much thinner flash drive.

Process of distribution: How do pods work?

Deep inside the vape’s console rests a sensor that detects changes in the pressure of its surroundings. The moment this sensor is tripped, it closes the circuit and frees the electrons overcrowding the negative end of the battery. These ions fly down the electrochemical gradient, through the console’s spring-loaded prongs, past pod’s two gold plates, ultimately running straight into the coil.

The coil is explicitly made to be resistive to electrical current (but this isn’t specific to vape coils. All materials possess some degree of resistance). This means that electrons will have a much harder time flowing through. The energy that was propelling them forward is instead transformed and dissipated as heat.

Meanwhile, as all of this is happening, the wick draws liquid from the tank. Through capillary action, the wick brings the e-juice face-to-face with a scorching coil. The vapor is sucked up the chimney and right into the mouth of the user.

Drawing a breath through the mouthpiece is what sets all of this in motion. Air rushes in through the gap between the aluminum casing and the console, causing a drop in pressure. When the vape is charged, the user only has to inhale. The device does everything else.

When the vape is charged, the user only has to inhale. The device does everything else.

Perpetrators of desire: Why do young vapers get hooked?

This simplicity, suspects Dr Rizalina Gonzalez, MD, Chairwoman of the Tobacco Control Advocacy Group of the Philippine Pediatric Society, wasn’t incidental. “This has been a hit with kids. The design really is for the youth,” she says. It may seem shallow, but the device has a sleek build, understated but premium.

In turn, such a streamlined design makes for an easily concealable vice, hidden away from the prying eyes of parents or teachers. Video streaming site YouTube, among other social media platforms, is awash with content like “10 BEST PLACES TO HIDE A JUUL!” or “How to Vape in School! (The Right Way).”

For some of these “stealth vaporizers,” as they have been dubbed, keeping the device low-profile has been a major point of marketing.

Dr Gonzalez recalls that after one lecture, a concerned mother approached her, horrified that she now has to be wary of her child’s USB pile, too. It turns out that what she thought was the cap of a flash drive could have been a pod cartridge all along. She had no idea.

But the clincher really is the flavoring, Dr Gonzalez says. “Mint is actually attractive for kids; Mango is actually attractive for kids … Crème Brulee is also for kids. Adults aren’t too particular to flavors.” Dr Gonzalez adds. “[What] really entices the kids to use this is they [think] it is not nicotine-laced, but that it’s just flavor.”

Once hooked, pod vapes reel the user in and lock them in place with nicotine. Because they are small in size, pod cartridges contain e-juice specifically brewed to pack a deceptively strong punch.

The nicotine that exists in pods is in salt form (as opposed to its free-base form, which dominates in traditional cigarettes and in some older vape models). This has the pointed advantage of being easier on the throat. This is a huge draw-in for kids and non-smokers who may not be used to a nicotine hit. Nicotine salts let them inhale what is ostensibly just flavored air and get a buzz off it.

Arguably more importantly, though, is that nicotine salts diffuse more easily through the lungs and into the blood, making it a more potent psychoactive substance.

“[What] really entices the kids to use this is they [think] it is not nicotine-laced, but that it’s just flavor.”

Potential of danger: What are the risks of using pods?

Inhaled nicotine can swim all the way up to the brain in well under a minute, where it seeks out and anchors to its partner receptors (known in science text books and papers as nicotinic cholinergic receptors, or nAChRs). Large and multiplex, nAChRs are common features of cells in both the central and peripheral nervous system.

They are also transmembrane proteins, meaning they span the cell’s double-layer membrane. Part of the nAChR complex is inside the cell; another is outside, ready to pick up signals from its immediate environment.

It is this external unit that nicotine attaches to which, in turn, opens and allows ions to flood into the cell. This triggers a complicated cascade of events that culminates in the release of dopamine, the pleasure chemical. Other substances are also released in the process, such as serotonin, endorphins, and GABA (γ-aminobutryric acid), among others, each responsible for a particular effect of nicotine on the body.

Over time, and as nicotine continues to flood the brain, the nAChRs become desensitized to it, essentially entering an inactive phase. In response, the body produces more of these receptors to attend to the constant influx of the substance.

But for any number of reasons (most commonly a dip in nicotine intake), some of these dormant receptors may recover and reactivate. When this happens, the brain starts to aggressively crave nicotine, and the body starts to feel the symptoms of withdrawal. Satisfying the urge of these receptors relieves this discomfort, but feeds into the cycle of dependence. Nicotine, then, packs a one-two punch: Using it feels great, and stopping feels awful. In kids and teens, this is especially concerning.

As a child grows and develops, so does the brain. But it doesn’t do so uniformly. Some parts mature faster, while others take more time. In adolescence, this process remains incomplete.

Particularly, the regions of the brain that are responsible for the reward system complete their development earlier than the parts involved in cognitive control. And so, for a handful of teenage years, the brain is more strongly motivated by thrill: it seeks out rewards, and is less deterred by the prospect of harm.

“The prefrontal cortex is the last to mature, usually at 18 to 25 years,” explains Dr Gonzalez. “The prefrontal cortex are the brakes.” Messing with the prefrontal cortex, in the way that nicotine does, before it matures completely makes for lifelong alterations.

“When this region is altered, it is now primed to seek out something pleasurable, and this is something they can’t control,” she adds. “This never happens in the adult,” she continues, because by the age of 25, the brain will already have finished establishing and cementing its neural networks, which by this point will be more resistant to chemical influences.

All of this, in total, uncovers an unfortunate combo: The appeal of pods is stronger for children, but so are the health consequences.

Nicotine, then, packs a one-two punch: Using it feels great, and stopping feels awful.

Point of detachment: Do pods really help smokers quit?

Though just a single data point in a large, diverse set of vapers, Paul’s experience drives this point home harder.

Right before Metro Manila was put under enhanced community quarantine, Paul lost his JUUL. It’s unfortunate, but he says he’s not inclined to purchase another one.

He says he never truly enjoyed the experience and, if he’s being honest, it wasn’t at all effective as a cessation or quitting tool. If anything, it was the exact opposite. “My nicotine use just worsened,” he says. “I still smoke three sticks a day. JUUL was just added onto that.”

In part, he says it’s because he doesn’t feel that JUUL scratches his itch hard enough. The hit is “not as thick as I want,” unlike how it is in cigarettes. Worse, it leaves him wanting for more. He keeps on expecting that free-base rough drag in the throat, the exact thing that nicotine salts take away.

Of course, it’s never going to come. That isn’t how pods were designed. Plus, in all likelihood, Paul isn’t who they were meant for in the first place. Tacitly, it looks like he understands this, which is why he’s going to stop looking altogether. “Yep, no more vaping, I think,” he says.  (To be continued)—MF

*Not his real name.
This story was produced under the ‘Nagbabagang Kuwento Media Fellowship Program Cycle 4’ by Probe Media Foundation Inc. (PMFI) and Campaign for Tobacco Free Kids (CFTFK). The views and opinions expressed in this piece are not necessarily those of PMFI and CFTFK.

Author: Tristan Mañalac

Tristan is a journalist based in Metro Manila, focusing mainly on health, science, and the environment. He writes daily clinical news for MIMS.com and does in-depth reporting on the side. Being formally trained in the life sciences, he once dreamed of starting his own lab. But these days, he finds his greatest joy in a bottle of beer and a beautiful sentence.

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