Joe Farrell, a 16-year Danville resident, knows firsthand that CPR can save a life in a sudden cardiac arrest.

In 2007, he saved a man who had collapsed on a golf course by administering CPR as they waited for a helicopter. One year later, Farell's life was saved by CPR after he collapsed at a party.

Farrell and 20,000 residents trained in CPR in the San Ramon Valley Fire Protection District are being called on to act as volunteer first responders to someone having a cardiac emergency in public — by using their iPhones.

As of Tuesday, a new version of the district's iPhone app will alert people trained in CPR of cardiac emergencies in the district's boundaries.

When you download the application and enable the CPR alert, you will receive a data message when 9-1-1 has been called and paramedics are on their way to a  cardiac-arrest emergency.

On first use, a message from the application reminds people who sign up to "respond in a safe, responsible and respectful manner."

Using the phone's GPS, a map will tell the user where the victim is as well as the location of the nearest automated external defibrillator (AED). The user would then go to the person and help until the fire department arrives.

It is the first iPhone application of its kind, and district officials believe it should be made available to fire departments worldwide. They are working to form an independent foundation to achieve that goal.

"This could be the most meaningful application ever written," said San Ramon Valley Fire Protection District Fire Chief Richard Price. "We have something that we really think is going to change the world."

The district announced Tuesday that Danville resident Dave Duffield, CEO and co-founder of Pleasanton-based software company Workday, will partner with developers to apply the open source code of the iPhone application to other fire departments' dispatch systems at no cost.

Media executive Tim O'Reilly, along with Jack Parow, president of the International Association of Fire Chiefs, will reach out to fire departments nationally and internationally.

O'Reilly said at a press conference Tuesday: "This is an example of how we should build new government services to have citizens help each other."

The concept for the application was developed about 18 months ago by Price and his staff. Last summer, a version was released without the CPR functionality.

Development of the application for the Android phone is in progress. There are plans to develop applications for other smart phones through the foundation, said Price.

The Fire District hopes the new application will encourage more residents in the San Ramon Valley to learn CPR.

Starting Friday, a public service announcement will play before all movies at Crow Canyon Cinemas and at Century Blackhawk theaters, encouraging moviegoers to download the app.

"It's volunteerism in an entirely new way," Price said."It's volunteering 2.0."

Learn more about the iPhone app and download it for free from the Apple store here.