Some of the agencies don't appear to have shared information before the blast.
Fertilizer plants that hold more than 400 pounds of ammonium nitrate, for instance, are required to notify the Department of Homeland Security. (Ammonium nitrate can be used to make bombs. It's what Timothy McVeigh used to blow up the Alfred P. Murrah Federal Building in Oklahoma City in 1995.) The West plant held 270 tons &mdash yes, tons &mdash of the chemical last year, according to a report it filed with the Texas Department of State Health Services, but the plant didn't tell Homeland Security.
Carrie Williams, a Department of State Health Services spokeswoman, told ProPublica that the agency isn't required to pass that information &mdash which is also sent to local authorities &mdash on to Homeland Security.
While the exact cause of the explosion is unknown, a federal official told the New York Times that investigators believed it was caused by the ammonium nitrate. The blast crater is in the area of the plant where the chemical was stored.
The plant also filed a "worst-case release scenario" report with the EPA and local officials stating there was no risk of a fire or an explosion. The scenario described an anhydrous ammonia leak that wouldn't hurt anyone.
Did any of these agencies fail to inspect the plant when they should have?
It's unclear. OSHA conducted the last full safety inspection of the plant in 1985. "Since then," the Huffington Post reported, "regulators from other agencies have been inside the plant, but they looked only at certain aspects of plant operations, such as whether the facility was abiding by labeling rules when packaging its fertilizer for sale."
You can view the full OSHA report here. Since 2011, OSHA has carried out inspections based in part on the level of risk that plants like the one in West reported to the EPA. Since the West plant had told the EPA there was no risk of a fire or an explosion, it wasn't a priority. The plant also may have been exempt from some inspections as a small employer. An OSHA spokesman told ProPublica that the agency would be investigating whether the plant had such an exemption.
As the Huffington Post also noted, the most recent federal safety inspection of the plant, in 2011, resulted in a $5,250 fine for failing to draft a safety plan for pressured canisters of anhydrous ammonia, among other infractions. (There's no evidence that anhydrous ammonia played any role in the explosion.)
Why was a plant that stored explosive chemicals allowed to be located so close to a school?
The EPA and other federal agencies actually don't regulate how close such plants can be to schools, nursing homes and population centers. In Texas, the decision is left up to the local zoning authorities.