The oil passages are located at the base of the sebaceous glands to oil, the daily dust and dirt of the environment lead to blackheads and blocked. Some people try and remove it by piercing it with a needle, pin or tweezers. These actions are wrong and unsanitary, and only then the blackhead worse. Blackhead extraction is a professional job. Never pick at them, or try to leave. You will not only damage skin tissue, but cause the skin to get infected, what an acne condition.
Reasons of blackheads.
Blackheads are small, fat-like plugs formed in resources from the accumulation of dirt, oil and bacteria. It is black and the exposed end, because of oxidation and not the presence of microbes. Generally do not cause itching or pain, but it is unsightly.