The common cold, according to the Mayo Clinic, is a viral infection that affects the upper respiratory tract. While harmless, its symptoms can make its sufferers miserable until they pass. A variety of reasons contribute to the development of a cold, and knowing these causes can help a person reduce the number of infections he gets each year.
Viruses
Arthur Schoenstadt, M.D. of eMedTV, explains that more than 200 viruses are responsible for the development of colds each year, the most common being the rhinovirus. This virus causes colds in approximately 30 to 35 percent of all adults, and are most active in the early fall, spring and summer.
Another common cause of colds in adults is the coronavirus. This is most active during the spring and summer, and of the 30 types doctors are aware of, only three or four affect humans.
Smoking
KidsHealth points out that those who smoke are more likely to suffer from colds than non-smokers. Their symptoms tend to be worse, last longer and lead to more serious conditions such as pneumonia or bronchitis.
Dry Air
Dry air lowers a person's resistance to the viruses responsible for the common cold. The rhinovirus, for instance, grows best in temperatures of 91 degrees Fahrenheit. As the virus grows in the nasal area, it thins the mucous membranes, which are a protective barrier against particles attempting to reach the lungs. Therefore, the thinning of these membranes to dry air makes the respiratory system more susceptible to infection.
Poor Hand Washing
The Centers for Disease Control and Prevention stresses that hand washing is one of the most important steps a person can take to prevent the spread of infection. Whenever a person coughs, sneezes or throws a tissue away, antibacterial soap should be the next item in her hands.
Infected People and Objects
Coming into contact with infected people or objects is one of the easiest means of catching the common cold. The virus-carrying droplets are in the air. Once a person coughs or sneezes, and a healthy person breathes these droplets in, the infection automatically begins.
The same holds true with certain objects such as door knobs, telephones or personal objects such as hairbrushes. An infected person begins spreading the infection by touching these objects.
