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