Fume is the general term for toxic gases produced by blasting.

NOx Fume produced from a surface blast.

The common fumes are carbon monoxide (CO) and oxides of nitrogen (NOx)

The group of gases known as Oxides of Nitrogen or NOx, of which the most common are nitric oxide (NO) and nitrogen dioxide (NO2), are often found as by-products in the post-blast gases of ammonium nitrate-based explosives. Together, these gases are loosely referred to as "NOx". Nitric oxide is invisible, but nitrogen dioxide ranges from yellow to dark red depending on the concentration and size of the gas cloud. These gases are toxic.

There are a number of causes for fume generation. These include:

• Explosives delivered into the blasthole with poor Oxygen Balance
• Lack of confinement in soft ground
• Loading into wet ground
• Dynamic desensitisation

The attached file provides detailed information on fume generation and management.