Loudoun County has at least 25 facilities that handle chemicals so dangerous they could kill or injure hundreds of people if there were a major leak or fire, according to county records. Fauquier County has nine high-risk sites, records show.

The facilities include light industry, retail businesses such as farm chemical suppliers and public utilities that use chemicals on the Environmental Protection Agency's "extremely hazardous" list.

The list was developed as part of a federal 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 throughout the Washington area; Fairfax County, with 65 sites, has the most in Northern Virginia, followed by Loudoun's 25 facilities and Prince William County's 21. Montgomery County in Maryland has the most overall sites, with 177. Comparisons are hard to make, however, because some counties have more industry than others and Montgomery has a stricter standard for reporting that boosts its overall total.

"We can reassure people that these facilities are very heavily regulated at the federal, state and local level," said Jeff Flippo, Loudoun's chief fire marshal. "We inspect these facilities twice a year--more than any other facility or business in the county."

Many of the facilities in Loudoun and Fauquier, especially telecommunications companies such as Bell Atlantic, store hundreds of batteries that power computers. The batteries contain thousands of pounds of sulfuric acid, a deadly corrosive.

If inhaled, sulfuric acid can cause serious damage to the lungs. Skin contact can lead to decay of tissue. When heated, the acid emits highly toxic fumes, and emergency officials usually recommend evacuating people downwind for at least a quarter-mile. But emergency personnel throughout the region say they believe the risk of a leak or fire involving the batteries is low.

Chlorine is the substance that worries emergency personnel most because of its prevalence and quick effect. As a gas, it becomes greenish yellow and is fatal if inhaled. Because of chlorine, every water treatment plant in the region is considered extremely dangerous by the EPA.

Chlorine is the most hazardous chemical at the Goose Creek Water Treatment Plant just north of Routes 659 and 642 near Ashburn, where a leak would threaten nearby subdivisions. Such plants are equipped with chlorine detection systems. The Leesburg, Hamilton, Lovettsville, Purcellville and Middleburg water plants in Loudoun and the Warrenton, Remington and Marshall water plants in Fauquier also use chlorine to clean water.

In addition to the risk posed by the permanent facilities, area residents face the threat of a random accident involving hazardous materials transported on major state highways and from natural gas pipelines crisscrossing Loudoun. Loudoun has no interstates or railroads, but Interstate 66 runs through Fauquier, which is also vulnerable to an accident on Norfolk Southern rail lines.

"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 neighboring Prince William County.

County officials acknowledge that Loudoun and Fauquier--like other D.C. area jurisdictions--lack all the personnel necessary to handle some types of serious incidents such as a chemical leak; outside expertise may be called in for that. Flippo said Fairfax County's hazardous materials unit is available to assist Loudoun's, as are state emergency response teams based in Arlington and Winchester.

Hazardous Chemicals in the Counties

Federal law requires local governments to maintain a list of facilities that store or use dangerous chemicals. Each jurisdiction must identify hazardous substances, analyze the risk those substances could pose to the surrounding community and develop emergency response plans in the case of a spill or accident. The maps below show facilities within Loudoun and Fauquier counties that have reported dangerous chemicals.

Loudoun

AMMONIA

Air Gas Mid Atlantic

SULFURIC ACID

Automata

Bell Atlantic (6 locations)

Dowty Aerospace Messier Services

Virginia Concrete

Virginia Power

CHLORINE

Air Gas Mid Atlantic

City of Fairfax Goose Creek Water Plant

Hamilton Waste Water

Leesburg Water Pollution Control

Leesburg Water Treatment

Lovettsville Aeration Lagoon

Middleburg Waste Treatment

Purcellville Chlorination Building

Purcellville Wastewater Treatment

Purcellville Water Treatment

Waterford Wastewater

OTHER CHEMICALS

Automata

Creative Urethanes

Dowty Aerospace Messier

Hamilton Waste Water

Leesburg Water Pollution Control

Lovettsville Aeration Lagoon

Med Surg

Middleburg Waste Treatment

Purcellville Wastewater Treatment

RSI

Southern States

Waterford Wastewater

Fauquier

AMMONIA

Ross Industries

CHLORINE

Blackwell Water Filtration Plant

Marshall Waste Water Treatment Plant

Remington Waste Water Treatment Plant

Warrenton Sewage Treatment Plant

OTHER CHEMICALS

Marshal Co-op

Marshall Waste Water Treatment Plant

Remington Farmers Co-op

Remington Waste Water Treatment Plant

Ross Industries

Southern States

Warrenton Farm Co-op

Warrenton Sewage Treatment Plant