There are conditions that can warrant sperm's existence or survival. Upon ejaculation, there are about hundreds of million sperm and some survive longer while others may die. The survival rate depends entirely on the medium of culture the sperm are in.
Sperm may die inside the male's body due to fever or body high temperature. It is heat sensitive and cannot survive in high temperature. In the man's testicles, the semen or seminal fluid provides a favorable environment. Here, the seminal fluid allows the sperm to be motile and in constant temperature. Inside the body, sperm lives for up to 74 days. The main reason why male's testicles are hanging further away from the man's body is that to protect the sperm from the heat of the body.
Sperm may also die due to the person's negative lifestyle. Alcoholism, smoking, drugs and others can affect sperm survival rate. Other man's activities like sauna bath, sun bathing and hot showers can also harm sperm. Other environmental factors like chemical dusts, pesticides, glues, silicons, solvents and other hazardous materials can affect sperm quality and quantity. The sperm dies when the ideal environment or medium is no longer met. If the organ involves in the production has been affected due to long-term illness or has been hit hard that causes it stopped working.
Once ejaculated outside the body, sperm dies in less than an hour. This is due to the unfavorable temperature and unsuitable condition. When the semen or seminal fluid that carries the sperm dries up the sperm also dies. For the sperm to survive at least for 3 to 7 days, the fluidity and temperature must remain the same or consistent like in a test tube in the laboratory or in a woman's cervix. The sperm's life span depends on pH, air, temperature and others. It is fragile and weak when exposed outside the male's body. The male donor has to submit sperm collection within an hour or else the sperm quality will be affected. The sperm stays motile for several hours and need to be frozen. It has to be handled with care, kept in warm or room temperature if preservation is required.