Explanation:

Firemen uniforms have coating of Melamine.
Melamine is an organic base chemical most commonly found in the form of white crystals rich in nitrogen. 

It has a number of industrial uses, including the production of laminates, glues, dinnerware, adhesives, molding compounds, coatings and flame retardants. Melamine is a name used both for the chemical and for the plastic made from it.

For further readings:

https://www.who.int/foodsafety/areas_work/chemical-risks/melamine/en/