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Caption: The sensor in the chip would identify the toxic chemical and send an alert to a central station and the cell phone carrier. Credit: DHS S&T

The revolution of cell phones has been adding much functionality to its use. Its function varies from in-built camera, MP3 player, GPS to online service. What if, in the future, new functions on our cell phones could also protect us from toxic chemicals?

Homeland Security's Science and Technology Directorate (S&T)'s Cell-All is such an initiative. Cell-All aims to equip cell phones with a sensor capable of detecting deadly chemicals.

Our goal is to create a lightweight, cost-effective, power-efficient solution, says Stephen Dennis, Cell-All's program manager.

How would this wizardry work? Just as antivirus software bides its time in the background and springs to life when it spies suspicious activity, so Cell-All would regularly sniffs the surrounding air for certain volatile chemical compounds.

When a threat is sensed, an alert ensues in one of two ways. For personal safety issues such as a chlorine gas leak, a warning is sounded; the user can choose a vibration, noise, text message or phone call. For catastrophes such as a sarin gas attack, details-including time, location and the compound-are phoned home to an emergency operations center. While the first warning is beamed to individuals, the second warning works best with crowds. And that's where the genius of Cell-All lies-in crowd sourcing human safety.

Anywhere a chemical threat breaks out-a mall, a bus, subway or office-Cell-All will alert the authorities automatically. Detection, identification, and notification all take place in less than 60 seconds. Because the data are delivered digitally, Cell-All reduces the chance of human error. And by activating alerts from many people at once, Cell-All cleverly avoids the long-standing problem of false positives. The end result: emergency responders can get to the scene sooner and cover a larger area-essentially anywhere people are, casting a wider net than stationary sensors can.

And the privacy issue? Does this always-on surveillance mean that the government can track your precise whereabouts whenever it wants? To the contrary, Cell-All will operate only on an opt-in basis and will transmit data anonymously.

To be sure, Cell-All's commercialization may take several years. Yet the goal seems eminently achievable: Just as Gates once envisioned a computer on every desk in every home, so Dennis envisions a chemical sensor in every cell phone in every pocket, purse or belt holster.