Mapping the Danger   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 maps below show facilities in the area that have reported dangerous chemicals. • D.C. and Surrounding Counties • Alexandria • Anne Arundel • Arlington • Fauquier • Howard • Loudoun • Prince William • Southern Maryland • Stafford

From chlorine at the giant Blue Plains sewage treatment plant in Southwest Washington to propane in a cavern near a Fairfax County neighborhood, highly dangerous substances are scattered throughout the District and 13 surrounding counties, posing a health threat if the chemicals leak in a plant accident.
• District, Fairfax, Montgomery: Some Localities Ill Prepared for a Spill

• Prince George's: County Lacks Chemical Plan That's Current

• Loudoun: Sites in Area Pose Possible Chemical Risks

• Prince William: Chemicals at 32 Area Sites on EPA's Hazard List

• Arlington, Alexandria: Areas Gauge Chemical Risks

• Howard: Toxic Risks Tracked by County

• Southern Maryland: Chemicals at 78 Area Sites on EPA's 'Hazardous' List

• Anne Arundel: County Makes Assessment of Toxic Risks

• Related Story: Worries About Terrorism Keep Data Off the Web