Arlington County has at least four 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. Alexandria has five such facilities.

The facilities in Arlington and Alexandria are mostly telecommunications companies with hundreds of batteries that power computers and other equipment. The batteries contain thousands of pounds of sulfuric acid, a corrosive chemical that the Environmental Protection Agency has put on an "extremely hazardous" list.

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

In all, there are 607 such facilities in the Washington area; only the District, with three facilities, has fewer than Arlington and Alexandria. Fairfax County, with 65 facilities, has the most in Northern Virginia. Montgomery County, with 177 sites, has the most in the Maryland suburbs of Washington. 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.

The plants store and use such materials as chlorine, sulfuric acid and ammonia, all of which can be fatal even in small amounts.

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.

Hazardous-materials specialists, including Alexandria Emergency Preparedness Director Charles McRorie, say they are confident that the risk of a leak or fire involving sulfuric acid is extremely remote. Arlington and Alexandria each count two Bell Atlantic facilities that store batteries containing sulfuric acid.

Although ammonia is used at the Mid-Atlantic Coca-Cola Bottling Co. plant on Seminary Road, McRorie says he is more worried about the risk to Alexandrians from the Blue Plains wastewater treatment plant across the Potomac River in the District. Deadly chlorine could waft across the water or leak from a railroad tanker car containing chlorine that is heading to Blue Plains through Alexandria.

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

In addition to the risk posed by facilities permanently located in Alexandria and Arlington, residents also face the threat of a random accident involving the transportation of hazardous materials at Potomac Yard, Reagan National Airport, Interstate 395 and other major routes through the area such as Glebe Road and Columbia Pike.

Arlington officials express concern in their plan about the challenge of evacuating high-rise buildings in Crystal City and Rosslyn, which have large daytime populations. They are also concerned about parts of Arlington with residential high-rises. They also note in their plans the need for Spanish-speaking emergency personnel.

For more on the region's chemical threat, visit The Post on the Web at www.washingtonpost.com/metro

HAZARDOUS CHEMICALS IN ARLINGTON

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 these substances could pose to the surrounding community and develop emergency response plans in the case of a spill or accident. The map below shows facilities within the county that have reported dangerous chemicals.

SULFURIC ACID:

AT&T

Bell Atlantic (2 locations)

C&P Telephone Co.

(This graphic was not available)

SOURCE: County hazardous materials response plan

HAZARDOUS CHEMICALS IN ALEXANDRIA

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 these substances could pose to the surrounding community and develop emergency response plans in the case of a spill or accident. The map below shows facilities within the city that have reported dangerous chemicals.

AMMONIA:

Mid-Atlantic Coca-Cola Bottling Co.

Potomac Electric Power Co.

SULFURIC ACID:

Bell Atlantic (2 locations)

Ogden Martin Systems

Potomac Electric Power Co.

OTHER CHEMICALS:

Potomac Electric Power Co.

(This graphic was not available)

SOURCE: City hazardous materials response plan