In 1999, the Massachusetts state fire marshal issued a cautionary advisory about a new security product: a surveillance camera designed to look like a smoke detector. "This action has created a great concern for us in the fire service," Stephen Coan said. "If this [security cameras as smoke detectors] becomes widely known, we feel that the lives of people will be placed in jeopardy. Out of fear of being watched and the loss of privacy, it is possible that people will begin to cover over smoke detectors, endangering their lives...." Marshal Coan was not alone in his concern: In 2004, New York officials forced local outlets to stop selling the device for many of the same reasons.

Whatever else this incident might teach, it certainly illustrates the complex relation of safety to security. On one hand, the missions have much in common: Both are concerned with the integrity of systems and the protection of people. Yet there are also deep differences: Safety defends against outcomes that are unintended; security, against planned malevolence. Security is comfortable with the languages of incentives and probability; safety, less so. Safety is usually defined by area (Is this a safe neighborhood?); security, often by systems. Safety is a state of mind; security is a procedure. Safety concerns itself with people; security worries about assets, which include but are not confined to people. Security divides the population into good people and bad people; safety treats everyone alike.

At least potentially, these variations can spark conflicts. Security and safety are both interested in access, but security likes to see small numbers of well-identified people moving slowly, while safety wants the option of evacuating large numbers rapidly, without regard to identity. Safety might want to clean up scenes of incidents; security, to secure sites and preserve evidence. Safety systems like to be conspicuous, generally accessible and simple to operate; security might have second thoughts about all those virtues. (And then sometimes security likes to be conspicuous, while safety might have objections, as in a store or school.)

Chemicals security is advanced significantly by underground storage; the EPA, which is charged with ensuring the safety of underground water reserves and is therefore concerned with leaks, makes that difficult. "EPA regulations on chemical storage tanks do not specifically address security, nor do they seek to balance security versus environmental protection," observes Roxanne Smith, press officer at the EPA.

Exactly.

Managing this relationship can therefore be complex. Differences create cultural barriers, and barriers-silos in the organizational context-can slow the diffusion of good ideas. For instance, some feel that safety has been slow to embrace security cameras, even for such simple and straightforward applications as incident review and training, and for monitoring procedure compliance. Sloan Foster, VP of marketing for ArmidaWare, that makes surveillance equipment, suspects that this reluctance does not reflect considered policy decisions as much as simple cultural inertia. "Safety people just haven't thought much about security cameras," she says. Of course there is a chicken-and-egg issue here-so long as the market is defined around security, which is what market development will focus on. As of July, not even Foster's own company promoted the safety applications of its products on its site.