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Department of Homeland Security Will Release Gas on NYC Subways

Subway
Subway via LWYang

If you take the subway this week, you'll be taking place in large scale research being done by the Department of Homeland Security. A harmless gas and particulate tracer material will be released into the subway system to test how a potential terrorist attack with an aerosolized substance would spread.

From the official DHS documents, the materials released will be two types of "DNATrax":

* Particulate Tracer Alternative P1: Aerosol release of DNA oligonucleotides (oligos) encapsulated in soluble maltodextrin particles (maltodextrin with oligos is referred to commercially as DNATrax) and tagged with a fluorescent Optical Brightener (referred to as DNATrax-OB). DNATrax-OB allows for quantification using PCR and fluorimetry, but not culture methods.
* Particulate Tracer Alternative P2: Aerosol release of P1 attached to amorphous silica particles (referred to as DNATrax-OB-Silica). DNATrax-OB-Silica allows for quantification using PCR and fluorimetry, but not culture methods.

More information about DNATrax is available in the video below. Both materials are being used to study how a biological attack would spread, but are typically used to track food so that a potential contamination could be traced back to its original source. The components released with the DNATrax are also frequently used in consumer products.

The release will be similar to a 2013 subway study led by the NYPD. This week's test will also use perfluorocarbon tracers used in 2013:

* Gas Alternative G1: Release of sulfur hexafluoride (SF6) gas within the subway system. Sulfur hexafluoride allows for real-time measurements using infrared spectroscopy and laboratory measurements using Gas Chromatography Mass Spectroscopy (GC-MS).
* Gas Alternative G2: Release of SF6 gas and three perfluorocarbon tracers (PDCB, PMCH, and mPDCH). The three perfluorocarbon tracers allow for higher sensitivity compared to SF6 due to their extremely low presence in the subway background.

Each release event will take place during rush hours at two separate stations simultaneously, a combination of either Grand Central Terminal 4/5/6 platform, Times Square 1/2/3 platform, or 34th Street Penn Station 1/2/3 platform. There will be five releases, each separated by a minimum of 23 hours, over the week-long period.

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