Environmental health comprises those aspects of human health, including quality of life, that are determined by physical, chemical, biological, social, and psychosocial factors in the natural environment. It also refers to the theory and practice of assessing, correcting, controlling, and preventing those factors in the environment that can potentially affect adversely the health of present and future generations.

Nutrition, soil contamination, water pollution, air pollution, safe drinking water, noise pollution, light pollution, waste control, and public health are integral aspects of environmental health.


There are six main nutrients that the body needs to receive: carbohydrates, proteins, fats, vitamins, minerals, and water. It is important to consume these six nutrients on a daily basis to build and maintain healthy body systems.

Ill health can be caused by an imbalance of nutrients, producing either an excess or deficiency, which in turn affects body functioning cumulatively. Moreover, because most nutrients are, in some way or another, involved in cell-to-cell signalling (e.g. as building block or part of a hormone or signalling ‘cascades’), deficiency or excess of various nutrients affects hormonal function indirectly. Thus, because they largely regulate the expression of genes, hormones represent a link between nutrition and how our genes are expressed, i.e. our phenotype. The strength and nature of this link are continually under investigation, but observations especially in recent years have demonstrated a pivotal role for nutrition in hormonal activity and function and therefore in health.

Soil contamination is the presence of man made chemicals or other alteration to the natural soil environment. This type of contamination typically arises from rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, leaching of wastes from landfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensity of chemical usage.

The concern over soil contamination stems primarily from health risks, both of direct contact and from secondary contamination of water supplies.


Health effects

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The major concern is that there are many sensitive land uses where people are in direct contact with soils such as residences, parks, schools and playgrounds. Other contact mechanisms include contamination of drinking water or inhalation of soil contaminants which have vaporized. There is a very large set of health consequences from exposure to soil contamination depending on pollutant type, pathway of attack and vulnerability of the exposed population. Chromium and many of the pesticide and herbicide formulations are carcinogenic to all populations. Lead is especially hazardous to young children, in which group there is a high risk of developmental damage to the brain and nervous system, while to all populations kidney damage is a risk.

Chronic exposure to benzene at sufficient concentrations is known to be associated with higher incidence of leukemia. Mercury and cyclodienes are known to induce higher incidences of kidney damage, some irreversible. PCBs and cyclodienes are linked to liver toxicity. Organophosphates and carbamates can induce a chain of responses leading to neuromuscular blockage. Many chlorinated solvents induce liver changes, kidney changes and depression of the central nervous system. There is an entire spectrum of further health effects such as headache, nausea, fatigue, eye irritation and skin rash for the above cited and other chemicals. At sufficient dosages a large number of soil contaminants cause death.

Drinking water is water that is intended to be ingested by humans. Water of sufficient quality to serve as drinking water is termed potable water, whether it is used as such or not. Although many fresh water sources are utilised by humans, some contain disease or pathogens and cause long-term health problems if they do not meet certain water quality guidelines. Water that is not harmful for human beings is sometimes called safe water, water which is not contaminated to the extent of being unhealthful. The available supply of drinking water is an important criterion of carrying capacity, the population level that can be supported by planet Earth.

As of the year 2006 (and pre-existing for at least three decades), there is a substantial shortfall in availability of potable water, primarily arising from overpopulation in lesser developed countries. Many nations have water quality regulations for water sold as drinking water, although these are often not strictly enforced outside of the developed world. The World Health Organization sets international standards for drinking water.

Environmental health services Environmental health services are defined by the World Health Organization as:

those services which implement environmental health policies through monitoring and control activities. They also carry out that role by promoting the improvement of environmental parameters and by encouraging the use of environmentally friendly and healthy technologies and behaviours. They also have a leading role in developing and suggesting new policy areas.

Environmental Tobacco Smoke(ETS), is a serious and deadly environmental health issue facing workers across the world. On June 27, 2006, the U.S. Surgeon General released an in-depth report which analyzed the body of science relating to the disease and death caused by secondhand smoke.

Sanitary sewer overflow (SSO) is a condition whereby untreated sewage is discharged into the environment, escaping wastewater treatment. This situation, also known as Wet Weather Overflow, is primarily meaningful in developed countries, which have extensive sewage treatment facilities. The main causes of SSO are:

* Infiltration of excessive stormwater into sewer lines during heavy rainfall
* Rupture or blockage of sewerage lines
* Malfunction of pumping station lifts or electrical power failure
* Human operator error at treatment plant facilities

Since a number of countries have essentially 100 percent treatment of domestic wastewater, an SSO episode is viewed as a significant breakdown in environmental control of water resources; for example, the USA, Japan, the United Kingdom and some other European countries strive for complete secondary treatment of all effluent and pursue vigorously shortcomings in the sewerage systems.

By far the most prevalent cause of Sanitary Sewer Overflow stems from heavy rainfall events which can cause massive infiltration of stormwater into sewerage lines. This circumstance is most prevalent in older cities whose subsurface infrastructure is quite old; Inflow into the sanitary lines can be caused by tree root rupture of subsurface lines or by mechanical fracture due to age and overpressure from trucks and buildings above.

Other modes of system failure can include power outage which may disable lift station pumps or parts of the treatment plant operations themselves; in fact, any mechanical system failure within a treatment plant can create a circumstance leading to overflow: breakdown of rotating arms of trickling filters, jamming of line gates, clogging of filters or grates etc. Furthermore, some forms of human error can infrequently lead to diversion of sewage and result in an overflow event.

Decentralized failures in dry weather mainly occur from collection sewer line blockages, which can arise from a debris clog, line rupture or tree root intrusion into the line itself. One of the main problems of a decentralized line failure is the difficulty of defining the location of overflow, since a typical urban system contains thousands of miles of collection pipage, and the central treatment plant has no way of communicating with all the lines, unless expensive monitoring equipment has been installed.


Human health impacts include significant numbers of gastrointestinal illness each year, although death from one overflow event is uncommon. Additional human impacts include beach closures, swimming restrictions and prohibition against consumption of certain aquatic animals (particularly certain molluscs) after overflow events. Ecological consequences include fish kills, harm to plankton and other aquatic microflora and microfauna. Turbidity increase and dissolved oxygen decrease in receiving waters can lead to accentuated effects beyond the obvious pathogenic induced damage to aquatic ecosystems. It is possible that higher life forms such as marine mammals can be affected since certain seals and sea lions are known to experience peaks in pathogenic harm.


Health care often accounts for one of the largest areas of spending for both governments and individuals all over the world, and as such it is surrounded by controversy. Though there are many topics involved in health care politics, most can be categorized as either philosophical or economic. Philosophical debates center around questions about individual rights and government authority while economic topics include how to maximize the quality of health care and minimize costs.


A traditional view is that improvements in health result from advancements in medical science. The medical model of health focuses on the eradication of illness through diagnosis and effective treatment. In contrast, the social model of health places emphasis on changes that can be made in society and in people’s own lifestyles to make the population healthier. It defines illness from the point of view of the individual’s functioning within their society rather than by monitoring for changes in biological or physiological signs.


The health care industry is one of the world’s largest and fastest-growing industries. Consuming over 10 percent of gross domestic product of most developed nations, health care can form an enormous part of a country’s economy. In 2003, health care costs paid to hospitals, physicians, nursing homes, diagnostic laboratories, pharmacies, medical device manufacturers and other components of the health care system, consumed 15.3 percent of the GDP of the United States, the largest of any country in the world. In 2001, for the OECD countries the average was 8.4 percent with the United States (13.9%), Switzerland (10.9%), and Germany (10.7%) being the top three.

According to Health Affairs, $7,498 will be spent on every woman, man and child in the United States in 2007, 20 percent of all spending. Costs are projected to increase to $12,782 by 2016.

The healthcare industry includes the delivery of health services by health care providers. Usually such services receive payment from the patient or from the patient’s insurance company; although they may be government-financed (such as the National Health Service in the United Kingdom) or delivered by charities or volunteers, particularly in poorer countries.

There are many ways of providing healthcare in the modern world. The most common way is face-to-face delivery, where care provider and patient see each other ‘in the flesh’. This is what occurs in general medicine in most countries. However, healthcare is not always face-to-face; with modern telecommunications technology, in absentia health care is becoming more common. This could be when practitioner and patient communicate over the phone, video conferencing, the internet, email, text messages, or any other form of non-face-to-face communication.


Health care

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Health care or healthcare is the prevention, treatment, and management of illness and the preservation of mental and physical well-being through the services offered by the medical, nursing, and allied health professions. According to the World Health Organization, health care embraces all the goods and services designed to promote health, including “preventive, curative and palliative interventions, whether directed to individuals or to populations”. The organized provision of such services may constitute a health care system. This can include a specific governmental organization such as, in the UK, the National Health Service or a cooperation across the National Health Service and Social Services as in Shared Care. Before the term “healthcare” became popular, English-speakers referred to medicine or to the health sector and spoke of the treatment and prevention of illness and disease.


Health

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Health is the level of functional and/or metabolic efficiency of an organism at both the micro(cellular) and macro (social) level. In the medical field, health is commonly defined as an organism’s ability to efficiently respond to challenges (stressors) and effectively restore and sustain a “state of balance,” known as homeostasis.

Another widely accepted definition of health is that of the World Health Organization (WHO), which states that “health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity”. In more recent years, this statement has been modified to include the ability to lead a “socially and economically productive life.” The WHO definition is not without criticism, as some argue that health cannot be defined as a state at all, but must be seen as a process of continuous adjustment to the changing demands of living and of the changing meanings we give to life. The WHO definition is therefore considered by many as an idealistic goal rather than a realistic proposition.

The LaLonde report suggested that there are four general determinants of health which he called “human biology”, “environment”, “lifestyle”, and “healthcare organization”. Thus, health is maintained through the science and practice of medicine, but can also be improved by individual effort. Physical fitness, weight loss, a healthy diet, stress management training and stopping smoking and other substance abuse are examples of steps to improve one’s health. Workplace programs are recognized by an increasingly large number of companies for their value in improving health and well-being of their employees, and increasing morale, loyalty and productivity at work. A company may provide a gym with exercise equipment, start smoking cessation programs, provide nutrition, weight or stress management training. Other programs may include health risk assessments, health screenings and body mass index monitoring.

An increasing measure of the health of populations is height, which is strongly regulated by nutrition and health care, among other standard of living and quality of life matters. The study of human growth, its regulators and its implications is known as auxology.

Wellness is a term sometimes used to describe the psychological state of being healthy, but is most often used in the field of alternative medicine to describe one’s state of being.


Exercise

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Physical exercise is the performance of some activity in order to develop or maintain physical fitness and overall health. It is often directed toward also honing athletic ability or skill. Frequent and regular physical exercise is an important component in the prevention of some of the diseases of affluence such as cancer, heart disease, cardiovascular disease, Type 2 diabetes, obesity and back pain.

Exercises are generally grouped into three types depending on the overall effect they have on the human body:

* Flexibility exercises such as stretching improve the range of motion of muscles and joints.
* Aerobic exercises such as walking and running focus on increasing cardiovascular endurance.
* Anaerobic exercises such as weight training or sprinting increase short-term muscle strength.

Physical exercise is considered important for maintaining physical fitness including healthy weight; building and maintaining healthy bones, muscles, and joints; promoting physiological well-being; reducing surgical risks; and strengthening the immune system.

Proper nutrition is just as, if not more, important to health as exercise. When exercising it becomes even more important to have good diet to ensure the body has the correct ratio of macronutrients whilst providing ample micronutrients; this is to aid the body with the recovery process following strenuous exercise. When the body falls short of proper nutrition, it gets into starvation mode developed through evolution and depends onto fat content for survival. Research suggest that the production of thyroid hormones can be negatively affected by repeated bouts of dieting and calorie restriction. Proper rest and recovery is also as important to health as exercise, otherwise the body exists in a permanently injured state and will not improve or adapt adequately to the exercise.

The above two factors can be compromised by psychological compulsions (eating disorders such as exercise bulimia, anorexia, and other bulimias), misinformation, a lack of organization, or a lack of motivation. These all lead to a decreased state of health.

Delayed Onset Muscle Soreness can occur after any exercise, particularly if the body is in an unconditioned state relative to that exercise.