Allegations of illegal marketing tactics. More than 500 cases of severe lung illness in 38 states. Eight deaths . A proposed federal ban of most flavored e-cigarettes, and new efforts in many states to counter an epidemic of youth vaping.

There’s been an avalanche of vaping news this month, which leaves many users facing a crucial question: Is it time to quit?

Here’s a look at the issues.

First, how big is vaping?

E-cigarettes swept onto the market about a decade ago. They’re now a $2.6 billion industry in the United States, and roughly 20,000 vape and smoke shops have sprung up across the country in the past few years. There is also a thriving black market for vape pods. A survey last year found that 10.8 million American adults used e-cigarettes — and that more than half were also smoking cigarettes.

E-cigarettes have become especially popular among teenagers. Preliminary results from an annual survey sponsored by the National Institute on Drug Abuse and released on Wednesday found that one in four 12th graders said they had vaped in the previous month, a sharp rise from the previous year.