New Emission Control System a Source for IEDs?

I ran into an interesting article over on AutoWeek.com earlier this week. It seems that Mercedes Benz is getting ready to sell a car in the United States that uses a urea solution to catalyze the elimination of NOx emissions from its diesel-engine. Each vehicle would carry a 7-gal tank holding a urea-water solution that would provide for vehicle operations for somewhat more than 10,000 miles. This is obviously not a place to discuss the merits of an automotive emissions control system. What make this development interesting in this forum is the fact the urea is a precursor to an easily made explosive, urea nitrate. This explosive is roughly equivalent to ammonium nitrate in its explosive power. It has been identified as being used in improvised explosive devices (IEDs) Urea as a COI Urea was included in the original DHS chemical of interest list published in the spring of 2007. It was listed as a theft/diversion IED precursor chemical. It had a 2,000 lb screening threshold quantity (STQ). DHS removed urea from the final version of Appendix A because they felt that it was easier to regulate Nitric Acid, the other chemical required to make urea-nitrate. When the current Appendix A was released the STQ for similar IED precursors was changed to 400 lbs of any commercial grade of the COI. If urea had not been removed from the list the amount of the urea solution in vehicle tanks would not be any where near enough to amount to an STQ amount. Refill tanks at vehicle dealers would certainly contain more than 400 lbs. Reconsidering Urea One of the major reasons that urea was removed from the COI list was that it was a widely used as both an agricultural and industrial chemical. This would have required too many facilities to be included in CFATS coverage. Since its required co-reactant is so much easier to control, it was easy to justify removing urea from the list of COI. This new use of urea (new in the United States, it has been used in this application in Europe for a couple of years now) might require a rethinking of the COI status of the chemical. The dispensing tanks of urea-water solution will be found in dealerships in urban and suburban areas where urea has been rare. With ‘home-grown’ terrorists more often found in these same areas, this may present too tempting a target. Alternatives to Appendix A Listing Is this enough to justify adding urea back to Appendix A? Probably not. The original risk calculation outlined in the Final Rule still applies to the vast majority of facilities that use urea. There is an alternative. The Secretary has the authority to designate individual facilities or classes of facilities as high-risk without regard to the Appendix A status of chemicals in use at the facility. Needless to say, the security requirements for a facility with a relatively small tank of urea-water solution will be significantly less complex than for a facility with a large chorine storage tank. That is one of the reasons that the risk-based performance standards used to evaluate site security plans is so valuable. It will allow facilities to scale their security plans to the actual risk at that site. Risk Analysis Is the risk of theft of this urea-water solution sufficient to require the Secretary to single out these car dealers? I’m not sure. I don’t have the intelligence information necessary to adequately weigh the answer to this question. I do think that the rise of a new class of uses for an IED precursor justifies a DHS review of the status of that chemical.