A $15 billion e-cig startup that's taking over the US is moving into London

• Silicon Valley e-cig startup Juul Labs is bursting at the seams.
• On the heels of a $15 billion valuation, the company is rapidly expanding in the US and opening the doors to its first international office in London on Tuesday.
• After London, Juul plans to launch in three more countries.

---

Standing in the bustling lobby of a San Francisco warehouse where employees zoom past one another carrying trays of freshly-prepared lunch, you wouldn't know you'd just set foot in the headquarters of an e-cigarette company.

But Juul Labs is bursting at the seams, with employees on every floor from the basement to an attic with no air conditioning. The company's popular vape pen, called the Juul, packs a uniquely powerful nicotine punch, and it has singlehandedly revived the once-flatlining e-cig industry.

On the heels of a $15 billion valuation and news of plans to raise $1.2 billion, Juul is opening its first international office in London on Tuesday.

After London, the company plans to open its doors in three additional countries - France, Singapore, and Israel. The international move parallels a similar expansion in the US, where staff sizes have tripled in the last six months alone.

Currently headquartered at a 5-story warehouse in San Francisco's Dogpatch neighborhood (with plans to spill into a larger building across the street), Juul is opening offices in 19 more locations across the country, from big cities like Boston and Chicago to smaller locales like Des Moines, Iowa and Manchester, New Hampshire.

But as it expands, Juul faces several challenges, including local laws limiting the sale of its products, concern from teachers and parents over the rise of teen vaping, and investigations into its advertising practices.

The rise of 'Juuling'

Juul users - some of them current and former adult smokers; others kids and teens - swear by the device because of its powerful concentration of nicotine, discrete design, and satisfying flavors, which include everything from Virginia Tobacco to Creme Brulee and Cool Cucumber.

The most popular e-cig on the market, the Juul has even spawned its own verb: "Juuling."

But while adult Juuling (instead of smoking) is largely considered a benefit to public health because it's less dangerous than inhaling burned tobacco, teen Juuling represents a massive and unforeseen concern - at least in the US, where a growing cadre of researchers is sounding the alarm on the vape pen's addictiveness.

Scientists are especially worried about the young users who may otherwise have never smoked but instead pick up a Juul, as several well-designed studies suggest that young people who vape are significantly more likely to go on to smoke traditional cigarettes.

In addition to concerns from public health experts and researchers, the Juul is facing legal pressure. Last month, the city of San Francisco banned the sale of flavored tobacco products that includes Juul flavor packs, known as Juul Pods. Also, the Food and Drug Administration is investigating whether Juul has marketed its products to teens.