The provisions of this article shall not apply, except as noted herein specifically, to any nonconforming industrial use located in a residential zone, which use exists on the effective date of this chapter; provided, however, that no change is made in the basic type of industrial operation or no additions are made to the existing operation which are noxious, offensive, hazardous or detrimental to the comfortable enjoyment of life or which are injurious to human, plant or animal life and property or to the health, safety and general welfare of the community.