The cartilage rings are C-shaped because the back of the trachea presses against the esophagus. The cartilage opens at the esophagus and is replaced by connective tissue and muscle. This gives the esophagus space to allow food to be swallowed easily. The rings of the trachea are stacked one on top of the other, with a small space between them.
In 2014, a survey of the Australian working population revealed that the most common carcinogenic exposures in the workplace were solar ultraviolet radiation, diesel engine exhaust, environmental tobacco (second-hand) smoke, benzene, lead and silica.
Squamous Cell Carcinoma. Squamous cell carcinoma is the second most common type of skin cancer and has the strongest association with sun exposure. This skin cancer type usually develops in places on the body that have been exposed to the sun, like ears, the face and the mouth, but can develop anywhere on the body.