Which layer of skin is primary barrier against environmental hazards?

The primary barrier against environmental hazards in the skin is the epidermis. The epidermis is the outermost layer of the skin, and it consists of multiple layers of cells that are tightly connected to each other. The outermost layer of the epidermis, called the stratum corneum, is made up of dead skin cells that are filled with a waterproof protein called keratin. Keratin helps to protect the skin from damage by chemicals, UV radiation, and microorganisms. The epidermis also contains specialized cells called melanocytes, which produce the pigment melanin. Melanin helps to protect the skin from UV radiation, and it gives the skin its color.