Disaster alert? Check your cellphone.

California weighs using text messages to warn residents during emergencies.

When a wildfire threatened resort areas of Catalina Island off Los Angeles last week, authorities used bullhorns to spread word of an evacuation.

If the lieutenant governor gets his way, officials trying to warn Californians of fires, floods, toxic spills, or earthquakes will have an additional tool: cellphones.

"All of the cellphones within range of those towers [on Catalina Island] would ring with an emergency message," says Lt. Gov. John Garamendi (D), describing the proposed cellular alert system, which could use text and voice messages. "Visitors as well as residents on the island who had cellphones, pagers, BlackBerrys, etc., would get the message."

Cellphones are now ubiquitous – outnumbering land lines in the US – making them an obvious part of any emergency alert system. Yet the necessary broadcasting technology has lain dormant for more than a decade, absent a strong push and planning effort by government agencies.

"Cell broadcast has been around for at least 10 years, but there's never really been a business driver for it. And so the cellphone companies haven't implemented that technology," says Art Botterell, a warning-systems expert. "It's something that they could do, but it's not quite turning on a switch. It does involve spending some money."

The lethargy around the issue has dissipated in the wake of the South Asian tsunami, hurricane Katrina, and most recently, the school shooting at Virginia Tech.

Congress last year passed the WARN Act, which calls for a cellular alert system. Mr. Botterell sits on a panel that will release recommendations in October for the law's implementation, which he expects sometime around the summer of 2008. California, meanwhile, announced last week that it isn't waiting on the feds.

The cellphone industry has representatives working with both efforts. "We think it can be done," says a spokesperson for the Cellular Telecommunications and Internet Association. "It just has to be done properly."

A thicket of complexities must be whacked through, ranging from the technical to the philosophical.

One obvious concern is misuse. It's a problem already evident in the limited text-message alert systems already in place. Some states, cities, and institutions across the country have opt-in systems, where people can put themselves on a list to receive cellular alerts.

"The real danger is that once a technology is implemented that you'll get all kinds of municipal spam," says Avi Greengart, principal analyst for mobile devices with Current Analysis, a market research firm in Virginia. "My kid's school calls my cellphone with automatic messages as stupid as 'the drop-off lane has shifted.' Well, frankly I don't care … and why are you using up my minutes?"

Mr. Garamendi assures that the California system would "only be used for true emergencies," determined by strict protocol. Text messages might also be paired with the warning tone familiarized by TV and radio alerts.

Then there's the question of who gets to issue warnings, and the related concern about false alarms – or even a hacker's prank – being broadcast.

Botterell, however, points out that "virtually nothing" happened when an operator accidentally activated the emergency broadcast system in 1971. "If you look at the actual research, panic is a very rare phenomenon," he says. And, as for people losing trust in the system, "it's not false alarms that cause people to desensitize," he adds, "it's irrelevant alarms."

Ensuring relevancy can be tricky. Different companies use cellphone towers and satellites in different locations, making it difficult to precisely target a message geographically.

One solution developed by Square Loop, a Virginia-based firm, is to put an applet, or small software program, on phones that would interpret warnings and judge their relevance before relaying them.

While at the moment this would require users to download additional software, there are several added benefits. Warnings can pinpoint very specific people, such as those who recently dined at the London hotel where the former Russian spy was poisoned. Location records stored on the phone remain private because it is the applet -- not the broadcaster – that looks at the logs.

The applet can also help solve some accessibility issues, says Joe Walsh with Square Loop. Deaf users can have emergency alerts vibrate, and text alerts can be read to blind users.

Both the federal government and California are thinking through issues of accessibility for the disabled and for non-English speakers. Those on both projects also emphasize that cellphone alerts won't replace other methods of notification.

"One technology by itself very rarely triggers a whole lot of action," says Botterell. Instead of compliance with emergency instructions, most people will gather more information first from TV, radio, or neighbors. "If they get enough corroboration from enough sources, then they become persuaded that it's not a false alarm."