After numerous New Yorkers expressed concerns about posters spotted in subway stations across New York City last week, claiming to offer safety advice against attacks and nuclear reactor failures, NYPD have issued a statement reassuring the public that the posters are in fact a hoax.

One poster is based on truth, highlighting the use of invisible test gases in the subway system as part of a city-wide anti-terrorism experiment – however, the gas mask illustrations and urges to “stay calm” present the activity as a far more risky assessment process than it really is. Another poster warns travellers: “New York City sits 28 miles away from the most at-risk nuclear reactor in the country. Stay calm and do not panic.” The additional tips, such as “Beware of southerly winds” and “Avoid breathing” should have been an indicator to the authenticity of the warnings, but that didn’t stop several members of the public contacting police and subway authorities.

The posters have been linked to local activism groups, as the timing coincides with a meeting about safety concerns in the nearby Indian Point nuclear power plant. Subway workers are now working to remove the notices and reassure travellers.