"At least 800,000 people across the United States live near hundreds of sites that store large amounts of potentially explosive ammonium nitrate, which investigators are blaming as the source of last month's deadly blast at a fertilizer plant in West, Texas, a Reuters analysis shows."
"Hundreds of schools, 20 hospitals and 13 churches, as well as hundreds of thousands of households, also sit near the sites. At least 12 ammonium-nitrate facilities have 10,000 or more people living within a mile.
Fourteen people were killed and about 200 injured April 17 when a fire at West Fertilizer Co. was followed by a massive explosion. Ten of the dead were first responders from area fire departments.
The explosion destroyed an apartment complex and nursing home that sat within a few hundred yards of the fertilizer plant, damaged homes within a half mile of the plant and cracked windows even farther away."
Ryan McNeill and M.B. Pell report for Reuters May 22, 2013.  The data journalism project includes an interactive map that allows users to locate schools, hospitals, and population in their own areas that are near ammonium nitrate storage facilities.