The I-G district provides land for industrial uses in which production and processing activities involve a degree of noise, vibration, air pollution, radiation, glare phenomena, and fire and explosive hazards. The physical effects of such phenomena shall be limited to levels as per the performance standards contained in Article V. Offices shall be permitted only when accessory and subordinate to the principle permitted use. This district is not intended to be customer-oriented, and retailing shall be permitted as an accessory use only.