Prince William County has at least 21 facilities that handle chemicals so dangerous they could kill or injure hundreds if there were a major leak or fire, county records show. Neighboring Stafford County has 11 high-risk sites, records show.

The facilities include manufacturers, warehouses, retail businesses and public facilities that use chemicals the Environmental Protection Agency has put on an "extremely hazardous" list.

The list was developed as part of a program to help local governments identify chemical risks in their communities and work with the facilities to lower the chances of a catastrophe. The governments' hazardous materials response plans are public records, and The Washington Post reviewed them to determine how many high-risk facilities are in the region and whether government officials are prepared for a disaster.

In all, there are 607 such facilities in the Washington area; Fairfax County, with 65 sites, has the most in Northern Virginia, followed by Loudoun County's 25 and Prince William's 21. Montgomery County in Maryland has the most sites overall, with 177. Comparisons are hard to make, because some counties have more industry than others and Montgomery has a stricter standard for reporting that boosts its overall total.

In addition to the risk posed by the permanent facilities, county residents also face the threat of a random accident involving hazardous materials on Prince William and Stafford's major highways, CSX and Norfolk Southern railroad tracks and several natural gas and petroleum pipelines.

Interstate 95, which runs through eastern Prince William and Stafford, carries hundreds of trucks hauling dangerous cargo. Interstate 66 bisects western Prince William, and several major state roads crisscross the county.

"Transportation is often the greater threat because, unlike a fixed facility, you don't know when or where those incidents are going to occur," said John Medici, the emergency preparedness director in Prince William.

About 50,000 people live at the northern end of I-95 in Prince William. An incident at the point where I-95 comes close to the CSX tracks and Route 1 would cripple all three routes.

Medici acknowledges that Prince William--as is the case with other Washington area jurisdictions--lacks the personnel to handle some types of serious incidents, such as a chemical leak; outside expertise may be called in in that event. But local emergency personnel would have to deal with the incident until help arrived.

County officials said they are confident that most of the facility owners have taken steps to reduce the likelihood of a leak or fire.

Colonial Circuits Inc., in Stafford, makes circuit boards, using five dangerous chemicals. The facility has a fire detection system, though no chemical leak detector as some plants do. But the ventilation system is equipped with a "scrubber" that removes hazardous airborne substances.

During a fire, Stafford fire officials recommend that firefighters avoid entering the building to extinguish the blaze because of the potential of a hazardous chemical reaction of the substances. Instead, officials suggest evacuating the area, which includes a five-story Geico Corp. office building with 3,500 people.

Prince William has worked with site owners to reduce risks. Medici said Dominion Semiconductor in Manassas has sought to keep its chemical inventory to minimum levels, reducing its risk to workers and the community. But the downside is that Dominion requires more shipments on the county's transportation network, Medici said, "so it's a trade-off."

CAPTION: (This graphic was not available) Hazardous Chemicals in Prince William

CAPTION: (This graphic was not available) Hazardous Chemicals in Stafford