Natural environmental factors: including physical environment, chemical environment and biological environment. Physical factors in the environment, such as temperature, humidity, airflow, air pressure, solar radiation, noise, vibration, electromagnetic radiation, etc. These factors often have a dual impact on people. When the intensity, dose or time of these physical factors exceed a certain level, it will cause harm to the body. For example, moderate sunlight can make the body have anti-rickets effect, but excessive sunlight can lead to sunburn and skin cancer.
Chemical factors in the environment include factors inherent in the earth's surface, human activities and natural disasters. These factors have beneficial or harmful effects on human health, or both. For example, iodine deficiency in geological environment will lead to local goiter; Chemical substances produced by human activities, especially those contained in waste gas, waste water and waste residue, will pollute air, water, soil and food and cause harm to human body.
Biological factors in the environment include various organisms in the biosphere, among which pathogenic microorganisms harmful to human health include bacteria, viruses, parasites, fungi and so on. They generally do harm to human body through air, water, soil and food.
Social and environmental factors. It is the social condition for human life, socialization of production and other activities. Including political system, economic situation, culture and education, scientific and technological level, living conditions, nutrition level, employment situation, population situation and so on. These factors can influence each other, directly or indirectly affecting human health. Family factors are also social environmental factors. Dramatic changes in family factors, such as divorce, widowhood, and family discord, lead to tension, anxiety and sadness. It can be a direct or indirect factor inducing diseases.
Personal behavior. Such as bad living habits, smoking, drinking, taking drugs, not paying attention to sports activities, taking drugs, sexual promiscuity and so on. These unhealthy lifestyles are the most important health threats of our time.