Isobutylene: What it is and what it's used for

Isobutylene is the chemical burning at the KMCO plant in Crosby, but what is it, and what are the risks?

Isobutylene is associated with rubber products and fuel production.

Generally kept under pressure as compressed, liquified gas, it is highly flammable. If released, it can create an oxygen-deficient atmosphere, causing concerns of asphyxiation.