Last September, City Council Speaker Melissa Mark-Viverito declared East Harlem the "epicenter" of NYC's K2 crisis, following a frenzy of media coverage on the sale and abuse of the drug.

The mayor's office acted swiftly, raiding Harlem delis where K2 was believed to be sold, and criminalizing its sale and distribution. The feds made several large-scale K2 seizures. Then, in May, Mayor de Blasio announced triumphantly that the "epidemic" was essentially squashed—K2-related hospitalizations had decreased 85% since July 2015, from 1,200 cases at peak to about 180 this March.

Now, following a mass K2 overdose in Bed-Stuy, the chemical-drenched herbs are back in the spotlight.

"We took a lot of the product off the streets and out of the warehouses, and for a while it was tougher to get it on the street," James Hunt, the special agent in charge of the Drug Enforcement Administration's New York division, told the NY Times this week. "But it's back."

Here's our breakdown of the drug—what it's made of, where it comes from, and how it's being treated and policed.

What's K2 made of? I've heard it referred to as "synthetic marijuana." Is it just a chemical version of weed?

The most basic question is also the trickiest to answer, because K2 has no consistent chemical makeup. Dr. Indra Cidambi, an addiction specialist based in New Jersey, says that K2 is typically an innocuous plant leaf sprayed with chemicals that have been manufactured to vary slightly from banned compounds. They're known broadly as New Psychoactive Substances (NPS), are manufactured primarily in China, and can be purchased online. "They copy the effects of all of the illegal drugs," she explained. "Chemists just change the formulas a little bit. They add something to it... so the formula is not illegal."

Because it varies from batch to batch, the drug has essentially managed to stay one step ahead of the banned list. Governor Cuomo criminalized several strains of K2 in 2012, but ended up banning additional strains last year, following an uptick in hospitalizations.

Like weed, Dr. Cidambi added, most of the NPS chemicals in K2 are designed to latch on to your brain's THC receptors. They just latch much harder, and are often mixed without discretion. As a result, physical and psychotic reactions vary dramatically (we'll get to that).

"When [people] hear the word 'synthetic marijuana,' I think they have an image of somebody in a white lab coat in a lab, making something up according to a protocol," Health Commissioner Mary Bassett told reporters last fall. "It's not like that. The thing you should think of is somebody in a T-shirt in a warehouse, hosing down leaves with some concoction that's made up of chemicals that they bought on the internet that are called synthetic cannabinoids."

Where can I buy it? How much does it cost?

Before last year's crackdown, K2 was sold at many bodegas and smoke shops around the city, recognizable for its colorful, candy-like packaging. Raids in East Harlem and from large-scale distributors seem to have staunched the flow of the drug, but Bed-Stuy in-and-around the Myrtle Avenue J/M/Z station has remained a reliable spot to pick up K2. Many users and locals point to two local delis, though management at Big Boy Deli on the corner of Myrtle and Broadway has denied these accusations. Reports suggest a street-level resale market as well, by the joint. According to the NYPD, its sale tends to proliferate around homeless shelters and methadone clinics.

Anecdotally, users told us this week that prices have gone up incrementally over the last year. One user said he pays $2 for a packet, while another insisted $10, up from $5 six months ago. Regardless, the drug is less expensive than marijuana. "The K2 is taking over the weed," one user told us this week. "It's cheaper, and it's a better high."

US Attorney Preet Bharara during last fall's K2 investigation (Getty).

If I smoke it, what will happen to me?

The body's response to K2 is as unpredictable as the drug's chemical makeup. Dr. Robert Chin, the chief of the emergency department at Woodhull Hospital, treated all 33 people who overdosed on a single batch of K2 in Bed-Stuy this week. He described the patients as disoriented and lethargic. "I could describe it as a deep sleep," he told the NY Times.

"Some people might be walking around like zombies, some will be violent, some will be suicidal, and some will vomit or have fast heart rates," said Dr. Cidambi. The length of a high is also unpredictable, and can last for several days. She also stressed that not all reactions are volatile—some users simply feel elated, relaxed, or comfortably "out-of-body."

"When I started [using K2], I felt insane and tried to hug a tree," Dashi Lama, 27, told us this week. He says he used K2 for four years, and recently stopped. "And then slowly, I felt normal, the same, regular [when I smoked]."

Another user who declined to give his name said that he'd never gotten sick from the drug. "I don't know why," he said. "Maybe I'm healthy."

"My heart almost stopped one time, and I got tingly feelings in my veins, and I felt like I was going to pass away," another user said at a press conference last year.

Near the Myrtle Avenue J/M/Z station in Bed-Stuy, witnesses have increasingly reported people erratically wandering the streets and intimidating pedestrians, apparently on K2. One man was seen standing in the subway station with his pants around his ankles, urinating and waving one arm in a repetitive, manic circle.

Consistent users also experience cravings, for which Dr. Cidambi says there are no known suppressants. "With opioids you have options, but for these guys... there's nothing I can do for the cravings. And that makes it harder [to treat]."

What happens if I overdose?

There have been more than 6,000 K2 related emergency room visits in NYC since last year, according to the Health Department, and two confirmed deaths. But unlike more lethal drugs like heroin, K2 doesn't have an overdose treatment. Users in altered states have little choice but to wait it out.

Are there other ways to ingest K2, besides smoking it?

According to Dr. Cidambi, while most K2 users smoke the drug in joint-form, she's also spoken to users who brew the leaves into tea. "They say it's a bonding experience," she said, comparing the tea to weed brownies shared among friends.

Sample K2 packets

Is K2 illegal?

After Governor Cuomo's banned-substance approach proved ineffective, the mayor's office criminalized the sale and distribution of the drug. Individual distributors now face fines up to $5,000 and a year in prison, and shops can be slapped with civil fines up to $10,000. Bodega owners found guilty of selling K2 face the potential loss of their lucrative tobacco licenses. (Selling or manufacturing the drug was previously only considered a health code violation, carrying a $250 fine.)

In Bed-Stuy, the NYPD is also reportedly testing out the controversial nuisance abatement law—a circa-1970 law that empowers the NYPD to bring to court any business owner allegedly harboring illegal activity.

"If you don't run [your business] legally, then you can expect to have very frequent visits from us until we padlock you, get court orders to put you out of business," NYPD Commissioner Bratton said at a press conference in Bed-Stuy on Thursday. "We're coming after you big time."

The NYPD raided Big Boy Deli on June 30th, and one worker was arrested and charged with unlawful sale of K2. Follow-up raids at five local delis on Wednesday led to three arrests—all for possession or sale of loose cigarettes.


How is K2 being policed on the street?

Mayor de Blasio has been adamant that his K2-stomping approach is focused primarily on sellers and distributors.

"These laws do not punish the individuals that are held hostage and held in the grip of this toxic drug," he said, shortly after K2 was criminalized. "We understand that some of the people who use this drug are amongst the most vulnerable in our city, and often include those who are dealing with mental health issues already. So the law doesn't focus on attacking the victim. It focuses on criminalizing the process that brings this poison into people's hands."

But the recent media attention on Bed-Stuy has resulted in heavier policing near the Myrtle Avenue J/M/Z. Some users and members of the local homeless community say they've been noticing heavier "quality-of-life" policing.

Earlier this week, one homeless man said, cops arrested him for urinating behind the Myrtle Food Bazaar. "I was hospitalized," he said. "I took a piss on the street, and they took me to the psych unit. I wasn't smoking K2, though."

"The police presence to me is a problem," said Katie Hydell, a Bed-Stuy resident of four years. "It's ramped up a lot. They might move them [homeless people] around from here to there, but they're just harassing people."

You can check out the Health Department's K2 materials here.