It is unlawful for any person, firm, or corporation to hang, place, or expose any meat, or other articles of food intended for human consumption, in such manner that it will be subject to contamination from the floors or walls of the building where it is kept, or be exposed to flies, dirt, or other sources of contamination. No meat or other articles of food shall be placed on any counter, block, rack, or any other place without being properly screened or protected from dirt, flies, and other sources of contamination.