A large explosion which occurred in the Lebanese capital, Beirut, has released toxic air pollutants which may be extremely harmful to the health of those in the area.

The blast is thought to have been caused by the explosion of the highly reactive chemical ammonia nitrate. Ammonia nitrate is a common industrial chemical that is often used as a fertiliser.

Following the explosion, the U.S embassy in Beruit has said: “There are reports of toxic gases released in the explosion so all in the area should stay indoors and wear masks if available”.

Andrea Sella, a professor of inorganic chemistry at University College London, said: “Ammonium nitrate is a major industrial chemical with two principal uses – as fertiliser and as an explosive. Explosions are typically detonations that cause huge damage due to the supersonic shockwave, which is clearly visible in the videos. The orange plume above the explosion site is due to nitrogen dioxide, the toxic air pollution gas, and is a tell-tale sign of a nitrate-based explosion. This is a catastrophic regulatory failure because regulations on the storage of ammonium nitrate are typically very clear. The idea that such a quantity would have been left unattended for six years beggars belief and was an accident waiting to happen”.