Why is it important to know the factors affecting an individual's health?

It is important to know the factors affecting an individual's health because we cannot help an individual to be healthy unless we understand and can address those factors.  A person's physical and mental health does not exist in a vacuum.  There are countless examples of this. 

Let's take a person who has type 2 diabetes.  If we seek to help this person manage that disease, we must have a fairly comprehensive knowledge of this person's environment. An extreme example would be a homeless diabetic person who has no means of keeping insulin refrigerated, no means of eating the regularly scheduled healthy meals that a diabetic should maintain, and no way of keeping any cut or sore clean and free from infection.  This person, given a home, some education, and some financial resources, can remain in relatively good health for many years.  If this person remains homeless, he or she will most likely lose a limb through amputation, destroy kidneys and other organs, and die far earlier than he or she should have.  Homelessness is a factor that affects a person's health horribly.

A person who is bipolar should maintain as regular a schedule as possible for optimum mental health.  This person may have varying shifts at work or live in a household in which meals are not served regularly, and people stay up all night making noise.  The person may live alone and have no reminders to take medications or to take note of incipient mania or depression.  All of these may seriously aggravate bipolar illness, or for that matter, any number of other mental illnesses. 

Even in less extreme situations, there are so many factors that people in healthcare should have knowledge of.  A person who has asthma is going to suffer in environmental pollution.  The person who has had knee surgery and lives in a two-story house needs some help in arranging a way to heal.  The person who is trying to lose weight, yet lives in a household of cookies, cake, and candy, cannot accomplish this without some help from a dietician who is aware of the problem.  The elderly person who is living alone and who does not eat properly or drink properly is at high risk, but knowing of these factors, healthcare professionals can address these problems, to avoid dehydration, malnutrition, and even falls. 

All individuals are to at least some degree a product of their environments.  As such, their environments must be taken into account in order to help them be healthy in body and mind.