After weeks of policing and emergency response to a boom in the use of synthetic marijuana in New York City, the de Blasio administration launched its own public campaign to warn potential users of the drug's dangers.

Weeks ago, health officials said they were concerned that any informational campaign about the substance, commonly referred to as K2, would inadvertently lead to young New Yorkers learning of and potentially using the drug. 

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"We know that the those most affected are the residents of our poorest neighborhoods, residents of shelters, and those with psychiatric illness," said Health Commissioner Dr. Mary T. Bassett on Monday.

The main ad warns that K2 is "zero percent marijuana" and "100 percent dangerous" and will be posted in heavily affected neighborhoods, specifically on bus shelters, phone kiosks and inside businesses in East Harlem and the Bronx.

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The campaign comes on the heels of a new package of legislative reforms by City Hall that increased penalties that can result in up to $500 in fines per packet of K2, which usually retails for a few dollars per package.

New York has already seen two deaths and more than 6,000 emergency room visits since January.

However, most of the reported patients, city officials said, have a median age of 37, mostly live in city shelters and suffer from psychiatric illness.

The ad campaign differs greatly from the tack taken by the state Health Department, which in October launched TV ads that specifically feature young people and warn them about addition.