NF X10-702：防火测试方法.在不流通空气中测试烟雾的浑浊度
NF X10-702：Fire test methods．Determination of the opacity of the fumes in an atmosphere without air renewal．
The smoke density measurement taken from a material under fire conditions gives an indition of the visibility through the smoke,this is import as reduced visibility makes it more difficult to escape from a fire hence increasing the threat to human life from the toxic gas,flames and heat.
