The field of public health is not clearly defined yet, but certainly includes an emphasis on population based approaches to the prevention and amelioration of human disease and promotion of well-being and health. The practice of classic environmental public health has been extremely successful, because the infectious diseases appear to have been brought under control through advances in sanitary engineering that delivered clean water and safe food for the majority of population. The result was the increase in life expectancy as infectious diseases declined in the developed world while chronic diseases became epidemic.which contributes to the protection of the population as a whole, especially in groups sensitive to environmental agents.

Public health is an inherently multidisciplinary and collaborative discipline, In this book we consider public health issues describing briefly the public health terminology involved, followed by a detailed analysis of the main question: "Why are some people healthier than others?" There is evidence of the lifelong impact of childhood on health determined by maternal conditions and family circumstances. Connections to family, friends and community are strongly related to health status. It is widely accepted, that health condition is determined by lifestyle (50%), by human biology (20%), by the environment (20 %) and by the value of medical care (10%).

The key element of public health is the prompt response to different challenges of environmental attacks, risk assessment of multiple chemical exposures, infections, physical and radioactive effects. The impact of environmental chemical and physical agents is nowhere more evident than in the "built" environment. Hazard identification and dose-response relationships have become important in exposure assessment since human data are limited in toxicology. Epidemiology and the use of biomarkers in analytical epidemiology may help to bridge the gap between human and animal studies. Quantifying human exposure has also been the starting point for evaluating the usefulness of biomarkers in measuring the effect of environment. Exposure assessment enables the evaluation of genetic polymorphisms responsible for determining why individuals with identical levels of exposure have different degrees of target organ toxicity. Public health and environmental research also deals with global environmental health, especially the consequences of global warming. The issue of the environmental impact of emerging and re-emerging infections such as HIV (human immunodeficiency virus), SARS (severe acute respiratory syndrome) Ebola virus, dengue hemorrhagic fever, and resistant tuberculosis extends well beyond simple global climate- changes. Several theories and investigative methods dealing with the complexity of diseases and factors influencing human health will also be described in detail. On the exam important findings in the fields of epidemiology, occupational health, social medicine, and sociology, as well as the role of environmental and social influences in health maintenance and promotion will be considered.

Public health researchers may uncover potential solutions integrating their findings from epidemiology, biology, toxicology and social medicine. The most important approach of public health which might improve lifestyle is the primary prevention of cancer, infections, heart diseases, diabetes etc. to ensure public wellness.

Anna Tompa