Pollution snow is produced under specific conditions of atmospheric and meteorological pollution. The phenomenon is the following.
Atmospheric pollutants, in the form of aerosols, constitute freezing and condensation nuclei. The water vapour present in the air condenses on the pollutant particles and freezes, gradually forming snowflakes that end up falling. Elsewhere, where meteorological conditions are similar but the air is not full of aerosols, no snow forms.
Thus, localised snowfall occurs around pollution centres, near industry and in urban centres. This is why the term "industrial snow" or even "urban snow" is used.