What is ammonium nitrate?
Ammonium nitrate is a common industrial chemical used mainly for fertiliser because it is a good source of nitrogen for plants. It is also one of the main components in mining explosives.
Ammonium nitrate is not explosive on its own, rather it is an oxidiser, drawing oxygen to a fire and therefore making it much more intense.
Ammonium nitrate only ignites under the right circumstances, and these are difficult to achieve. It need extreme circumstances to set off an explosion.
While ammonium nitrate can in fact put out a fire, if the chemical itself is contaminated, for example with oil, it becomes highly explosive.
While the chemicals in the air should dissipate fairly quickly, lingering pollutants can cause problems later, for example if they acidify rain.
If you look at the smoke that came from the blast it’s this kind of blood red colour . That’s because of the nitrogen oxide air pollutants in it.