By Wein, Lawrence M.
Issues in Science and Technology , Vol. 23, No. 1
A terrorist attack on a single 90-ton chlorine tank car could generate a cloud of toxic gas that travels 20 miles. If the attack took place in a city, it could kill 100,000 people within hours. Now multiply that nightmare by another 100,000. That's the approximate number of tank cars filled with toxic gases shipped every year in the United States.
We are vulnerable to catastrophic acts of chemical terrorism such as this plausible scenario. There are 360 sites sprinkled across the United States where, if terrorists attacked, more than 50,000 people at each could be harmed or killed. Many of them are in heavily populated areas of New Jersey, New York, Pennsylvania, Texas, Louisiana, and California. Yet the federal government has made no progress whatever in addressing this threat in the five years since the 9/11 attacks.
Private industry has taken a few steps to make us more secure from chemical terrorism. The American Chemistry Council (ACC), which represents many of the nation's chemical manufacturing plants, has required its member facilities to undertake a set of security initiatives. They have invested several billion dollars in security upgrades since 2001. Although these private-sector investments may help with both safety (prevention of accidents) and security (prevention of attacks), two key shortcomings keep the ACC's efforts from providing the country with the level of security commensurate with the threat. First, the facilities that have invested in improved security number only 1,100, a small fraction of the 15,000 facilities that store or produce large amounts of hazardous chemicals. Even worse, they are not, by and large, the facilities that would injure or kill the largest numbers of people if they were attacked. Second, the stark reality is that a resourceful terrorist group can compromise any chemical facility or shipment that it puts its mind to.
The government finally appears to have become aware of the frightening state of our chemical plant security (although, as explained later, not of chemical transportation security). President Bush supports bills in the House and Senate aimed at hardening security at chemical plants based on the risks they pose. The legislation calls for the Department of Homeland Security (DHS) to place chemical plants into different tiers according to the results of offsite consequence analyses and set tier-dependent security standards. In turn, chemical plants would be required to assess their own vulnerabilities and choose how to improve security, if need be, to satisfy these standards. Facilities in the highest-risk tier would begin first.
Unfortunately, the bills do not go far enough. We need an approach that is both risk-based (so that investments in protection are made at the most dangerous facilities) and focused on the use of alternative, much safer chemicals (so that true prevention can be achieved.) The bills focus only on the degree of risk posed by a plant, not on safer processes.
The three main culprits
Chemical facilities vary widely in their attractiveness to terrorists. Obviously, measures should be aimed at plants and rail shipments that could generate mass casualties if attacked. As a result of the Clean Air Act, chemical facilities have already analyzed their potential worst-case offsite consequences from a chemical accident. That has made it possible to identify the most dangerous needles in the haystack of chemical facilities and shipments. We know that the most dangerous chemicals are not the flammable ones, such as liquid propane gas. The larger danger comes from chemicals that, on release, form heavier-than-air clouds that can travel 10 to 20 miles. We also know that there are three main culprits: chlorine (used in the production of building materials); anhydrous ammonia (used for agricultural fertilizer); and, worst of all, hydrofluoric acid (used in transportation fuels.) There may be several plants using less common chemicals that are equally dangerous. …