What is isobutylene?

CROSBY, Texas – Isobutylene is the chemical burning at the KMCO facility in Crosby, according to authorities.

So what is isobutylene? Here's a look:

Isobutylene is a highly flammable colorless gas with a faint petroleum-like odor. It is a gas at room temperature.

According to the National Fire Protection Association, isobutylene:

• Can cause temporary incapacitation or residual injury.
• Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.
• Normally stable but can become unstable at elevated temperatures and pressures.

PHOTOS: Tuesday's explosion in Crosby

The National Oceanic and Atmospheric Administration said isobutylene's "vapors are heavier than air and a flame can flash back to the source of leak very easily. The leak can either be a liquid or vapor leak. It can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket. It is used in the production of isooctane, a high octane aviation gasoline."

Behavior in Fire (info from NOAA)

Containers may explode in fire. Vapor is heavier than air and may travel a long distance to a source of ignition and flash back. 

Health Hazard (info from NOAA)

Inhalation of moderate concentrations causes dizziness, drowsiness, and unconsciousness. Contact with eyes or skin may cause irritation; the liquid may cause frostbite.