A Dallas Morning News investigation has found dozens of sites with hazardous chemicals that are in close proximity to residential neighborhoods. It is a problem throughout Dallas County. In some cases, plants and warehouses are within blocks — and even across the street — from homes, apartment complexes, and schools. Of the over 900 sites that story hazardous chemicals in Dallas County, 52 have quantities high enough that they must submit a worst-case scenario plan to the Environmental Protection Agency. This investigation explores how it happened and what can be done.