The mayor of New York City banned a substance some are calling 'weaponized marijuana'

The synthetic drug K2 is now illegal in New York City.

Mayor Bill de Blasio signed into law a legislative package aimed at stopping use of the drug and increasing the penalties for those who sell it.

"We are getting K2 off our streets and out of the hands of New Yorkers, and this legislation will improve quality of life for all New Yorkers," de Blasio says, calling K2 "a poison that threatens public safety and public health."

De Blasio noted that the new laws "criminalize sellers and manufacturers, without punishing users who are held hostage by this toxic drug."

Sale of the K2 or another synthetic drug known as "bath salts" is now punishable by up to a year in jail and up to $5,000 in fines. Additionally, the city can now revoke, suspend, or refuse to renew the licenses of cigarette dealers if they are found to be selling the drugs.

Synthetic marijuana, K2, and Spice are nicknames for synthetic cannabinoids, mind-altering drugs which can be up to 100-times more potent than traditional marijuana. The drugs, which are often produced in powdered form in underground labs in China, are shipped to the US, liquefied, and doused on dry plant matter.

The drugs are known to produce unpredictable and sometimes deadly effects.

The move comes after a summer marked by an escalation in K2 use and efforts by NYPD to crack down on its sale and distribution.

In early August, New York City's police commissioner, William Bratton, said that the drug, which he referred to as "weaponized marijuana," was of "great and growing concern" to the city's police force - which had seen a spike in hospitalizations from the drug.

The drugs have been responsible for 2,300 emergency room visits in New York City over a recent two-month period.

K2's potency, widespread availability, and price - a package can be purchased for as little as $5 at local bodegas - have made it increasingly popular in New York, especially among the young and the homeless.

In mid-September, the NYPD and the Drug Enforcement Administration conducted a joint operation, seizing around 300,000 "street-ready" packages of synthetic cannabinoids from 93 different New York City bodegas and delis and five suspected production warehouses, DEA spokeswoman Erin Mulvey told Business Insider.

The raid also yielded "three truckloads" of precursor chemicals and supplies capable of producing thousands more packages.

At one point, the problem became so bad that an entire block in East Harlem became known for the proliferation of bodegas that sold the drug and users hanging around smoking it.

Matthew Speiser contributed reporting to this article.