What is public health?

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Public health is a practice that focuses on the promotion of phys ical, mental, and social health and well-being and on the prevention of disease and disability among groups of people. It differs from the practice of medicine because it focuses on prevention rather than cures and addresses the needs of people as a whole rather than as individual persons.
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Public health is a practice that focuses on the promotion of physical, mental, and social health and well-being and on the prevention of disease and disability among groups of people. It differs from the practice of medicine because it focuses on prevention rather than cures and addresses the needs of people as a whole rather than as individual persons.

Public health is an evidence-based practice, which means that its professionals collect and analyze data to determine the health needs and risks of a population and then design programs to deliver services that will effectively address these needs and reduce risks.

Areas of Specialization

Public health encompasses many specialized fields of study, including epidemiology, maternal and child care, environmental health, injury prevention and control, addiction, health education and promotion, and health program management and administration. These specialties evolved as the correlations between health and sanitation, safety, and behavior were better understood. Each specialization addresses the specific needs of a community.


Epidemiology is the study of the relationship between causative agents and morbidity and mortality. This relationship may not be one of direct cause and effect, but the risk factors for a given illness are more likely to be identified. By determining the distribution of a public health concern, such as an infectious disease, within a population, commonalities may emerge that may then be tested for significance.

A classic example of epidemiology is the investigational work of John Snow, who looked into the source of a cholera outbreak in 1854 in central London. He began mapping the cases of cholera and found clusters in two areas. He interviewed the residents of these neighborhoods and found that they all had used the public water pump on one street. Direct examination of the water was inconclusive, but Snow’s logic had convinced officials to remove the pump’s handle, rendering it inoperable. Snow argued that the water company, Southwark and Vauxhall Waterworks, was delivering polluted water from the Thames River to this public well, which served areas that showed a high incidence of cholera. The cholera epidemic began to wane, although it could not be proven whether this occurred because of the pump’s water supply being discontinued or because people had already left the area to escape the disease.

Snow used statistics and surveys to determine the distribution of the disease and to identify common factors, suggested a plausible causative agent, and proposed an effective solution. Similar, refined methods are used today in epidemiology. For example, when the incidence of hantavirus infection suddenly increased in the western and southwestern United States between 1993 and 2007, epidemiologists used morbidity and mortality statistics to identify the trend and the geographical distribution. They looked for common factors and found weather patterns, vegetation, and rodents. Hantavirus was known to be transmitted when humans came in contact with the urine, feces, or saliva of infected rodents. The reason, however, for the sudden increase was not yet clear. When researchers began to study the relationships among common factors, they discovered that climate change (hotter, moister summers and warmer autumns) had nurtured increased vegetation, providing an increased food source (more seeds) for rodents. The rodents then had a greater survival rate in the winter months and multiplied at an accelerated rate. This increased rodent population propagated the hantavirus and shed it in greater quantities.

Maternal and Child Care

The primary goals of public health programs in maternal and child care are to reduce infant mortality, reduce the prevalence of child abuse and neglect, and extend the life expectancy of children. Studies indicate that for the first time, children in the United States may not live as long as their parents, primarily because of lifestyle choices and resultant chronic diseases rather than infectious diseases. According to the Centers for Disease Control and Prevention (CDC), the percentage of children between the ages of six and eleven who are obese had increased to 18 percent by 2012 because of poor nutrition, excessive eating, and a lack of physical activity. Obesity can lead to diabetes and heart disease, both of which reduce a person’s life expectancy.

Maternal and child health care begins with education in the schools about teenage pregnancy and providing access to prenatal care for all women. Although death during childbirth rarely occurs in the United States (14 deaths per 100,000 live births in 2015, according to the Central Intelligence Agency), women should have a safe, clean place in which to deliver with professional assistance. The rate of infant mortality is higher (5.87 deaths per 1,000 live births in 2015). Following birth, newborns need screening for diseases, disorders, and conditions so they can receive prompt and appropriate treatment and support. Newborns also benefit from breast-feeding and vaccinations. New mothers should also be screened for postpartum depression. Because mothers are still the primary caregivers, they must be taught about nutrition and healthy lifestyle choices for their children. In addition, they must have resources to care for children with special needs, such as autism, epilepsy, sickle cell disease, and hemophilia. Public health programs address these aspects of maternal and child health care, targeting at-risk populations such as teenagers, immigrants, and isolated rural residents.

Environmental Health

Environmental health involves the study of the human relationship with the surrounding world, or environment. Areas of study include outdoor air quality, water quality, waste management, agriculture, and chemical exposure. Environmental health professionals also inspect buildings for health hazards such as sick house syndrome, mold, radon, and infestations. They monitor climate changes because temperature and precipitation affect the spread of waterborne and food-borne diseases caused by bacteria, viruses, and parasites. Children are more sensitive than adults to their environment, so professionals also study allergies, asthma, chemical sensitivities, and secondhand smoke to improve pediatric health.

Environmental health specialists also influence a community’s infrastructure. They determine access to public transportation for subsequent access to health care and similar resources; help create bike paths, hiking trails, and outdoor recreation areas for public exercise; and work on systems for emergency preparedness and response. Such emergencies include major collisions and explosions that result in mass casualties, chemical spills, radiation leaks, natural disasters and severe weather, and infectious disease outbreaks.

Injury Prevention and Control

Injuries, which contribute to disability and death, are public health concerns. Injuries are like diseases because they have underlying causative factors, they have identifiable risk factors that increase their likelihood, and they have factors that make them preventable. Injuries may be divided into two categories: unintentional injuries and injuries caused by violence.

Unintentional injuries include motor vehicle collisions, falls, drowning, sports collisions (with other players or with equipment), burns and electrical injuries, and exposure to toxic chemicals. Public health addresses traffic safety (drinking and texting while driving and wearing seatbelts when driving), the regular use of protective equipment (motorcycle helmets, bicycle helmets, and athletic mouth-guards), chemical safety (medication interactions, binge drinking, and child-proofing home medicine cabinets), and identification of potential hazards in the home and workplace. The prevention of unintentional injuries reduces the expense of medical care, lowers the incidence and cost of long-term disability, and decreases the number of deaths from unnatural causes.

Violence is the intentional infliction of pain and injury and may result in death. Although it is usually perpetrated by one person against another, it may be carried out by a group of people or it may be self-inflicted. Public health programs address issues such as street gangs, domestic violence, child abuse, teen suicide, and self-mutilation. These can become epidemics depending on a community’s socioeconomic status and access to professional resources with healthier alternatives.

Substance Use, Abuse, and Dependency

Public health professionals are concerned with the use of substances that have detrimental health effects. These substances include tobacco, alcohol, and a variety of drugs. According to a 2015 report by the United Nations, in 2013, twenty-seven million people worldwide were classified as problem drug users. Nicotine addiction significantly contributes to heart disease and lung disease, making it the foremost lifestyle-related cause of death worldwide.

One goal of public health agencies is to educate people about the dangers of substance use, misuse, abuse, and dependency. Use is the habitual ingestion of and misuse is the use of a substance for which it was not intended, such as inhaling aerosol propellants to get intoxicated (or high). Substance abuse involves dangerous actions and continued use in the face of negative consequences. Dependency has a strong psychological component and physiological need.

Another goal of public health agencies is to promote substance abuse and dependency as diseases. Agencies seek to foster understanding from families and communities that will encourage users to seek treatment. Cessation programs begin with withdrawal or detoxification and continue with behavior modification therapy on an inpatient or outpatient basis.

Public health agencies may also seek to ameliorate the effects of substance abuse. For example, methadone clinics may be established to help people who are otherwise unable to give up illegal drugs. Clean needles may be distributed to reduce the spread of infectious diseases from sharing needles among intravenous drug users. Because sex is often “traded” for drugs, condoms may be distributed to reduce the spread of sexually transmitted diseases.

Health Education and Promotion

The first goal of health education and promotion is to improve the health of persons and families by providing accurate, timely, and understandable health information. According to the analysis by the National Center for Education Statistics of the National Assessment of Adult Literacy, which was conducted in 2003 and included a section specifically targeting health literacy, most adults (53 percent) have intermediate health literacy, meaning they can comprehend and apply some of the health information they read, but 14 percent have below-basic health literacy, meaning they can comprehend very little and apply almost none of the health information they read. Health information may be presented through brochures, posters, newspaper and magazine articles, and radio and television programs, and on websites. Many presentations are bilingual, depending, especially, on the region.

The second goal of health education and promotion is to create resources within the community to encourage and sustain a healthy lifestyle. These resources include school-based health centers; workplace programs such as stress management and smoking cessation (in support of a smoke-free environment); health fairs that showcase wellness resources such as yoga classes, massage therapists, and organic food shops; and community clinics for family planning, blood pressure monitoring, and flu shots.

The third goal of health education and promotion is to advocate for the public health needs of communities by educating politicians on the health issues that are affecting their constituents. Using the evidence-based approach, public health officials can statistically define a community’s needs, propose well-established strategies for meeting those needs,outline the resources necessary to implement the strategies, and offer quantitative measures of the outcome. The desired results of such advocacy are effective legislation, such as health care reform acts, and appropriated funding for national, state, and local public health programs.

Health Program Management and Administration

Public health departments are found at the federal, state, and local levels. They maintain databases that include information on morbidity and mortality, births and deaths, and records of inspection of public places, such as restaurants and swimming pools. The departments operate laboratories for testing air, water, and soil samples and for investigating microorganisms. They conduct epidemiological surveillance and investigations into communicable diseases to prevent epidemics. They often work with other agencies, such as clinics,schools, businesses, and other government agencies.

Professionals in health program management and administration are frequently responsible for grant writing and reporting and for overseeing budgets and managing resources. Successful health programs depend on appropriate planning and design that are based on an accurate assessment of community needs. Measurable goals and objectives must directly arise from these data. The programs also depend upon timely implementation with adequate attendance by the target population. Finally, the programs depend on quantitative evaluation and plans for sustaining the results. Effective public health efforts must also consider the social, economic, and cultural characteristics of the communities they serve.


At the end of 2010, the US Department of Health and Human Services released its Healthy People 2020 program, which includes national health goals and objectives through 2020. Several hundred objectives cover twenty-eight priority areas of public health. The focus of this program is not simply to reduce disease and death rates; its goal is to improve quality of life and increase the years of healthy living. Morbidity and mortality rates are easy to collect for specific populations and to analyze by cause. Life expectancy in the United States, however, has increased significantly since 1979, so these rates are less relevant than are reduced disability, premature death, and improvements in pain control and functional capacity.

A second focus of this program is to eliminate or, at minimum, greatly reduce health disparities for racial and ethnic minority groups, people with physical or mental disabilities, socioeconomically disadvantaged people, and the elderly. Disparities are pronounced in infant mortality, cardiovascular disease, diabetes, and human immunodeficiency virus (HIV) infection. Public health professionals believe that all members of a community should have access to health education, disease prevention information, and medical care, based on the ideal of social justice.

An executive report released in 2014 stated that progress had been made on four significant objectives: fewer adults were smoking cigarettes, fewer children were exposed to secondhand smoke, more adults were meeting physical activity targets, and fewer adolescents were using alcohol or illegal drugs.

The effectiveness of public health initiatives has led to a shift in the major cause of death: from infectious diseases to chronic diseases. Although some future initiatives will continue to aim for the reduction of the incidence of infectious diseases, others will address lifestyle-related choices, such as obesity and cigarette smoking, which are controllable risk factors for chronic diseases.


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