A Saudi man being sought by the FBI because he may be planning terrorist attacks has been linked to Jose Padilla, an American citizen charged with plotting to detonate a radiological "dirty bomb" in the United States, The Associated Press reports.

The FBI asked law enforcement and the public to be on the lookout for Adnan G. El Shukrijumah, 27, who officials said has received flight training and possesses a Florida driver's license.

"El Shukrijumah is possibly involved with al-Qaida terrorist activities and, if true, poses a serious threat to U.S. citizens and interests worldwide," the FBI said in a statement.

Homeland Security Department Secretary Tom Ridge has issued a series of information bulletins describing possible terrorist activity through a new Web site located at http://www.ready.gov.

Land Line will share the information with readers in the following weeks. Today's installment explains the basics of a dirty bomb.

A radiation threat or dirty bomb is the use of common explosives to spread radioactive materials over a targeted area. It is not a nuclear blast. The force of the explosion and radioactive contamination will be more localized.

While the blast will be immediately obvious, the presence of radiation will not be clearly defined until trained personnel with specialized equipment are on the scene. As with any radiation, you want to try to limit exposure.

To limit the amount of radiation you are exposed to, think about shielding, distance and time.

As with any emergency, local authorities may not be able to immediately provide information on what is happening and what you should do. However, you should watch TV, listen to the radio or check the Internet often for official news and information as it becomes available.

For more general information, see the "Are you Ready?" section of the Federal Emergency Management Agency Web site, at http://www.fema.gov/areyouready/.