Environmental Health

Environmental health is the branch of public health that is concerned with all aspects of
the natural and built environment that may affect human health. Health is the science,
practice, and study of a human's well-being and their health and preventing illnesses and
human injuries. Other terms referring to or concerning environmental health are
environmental public health, and public health protection / environmental health
protection. Environmental health and environmental protection are very much related.
Environmental health is focused on the natural and built environments for the benefit of
human health, whereas environmental protection is concerned with protecting the natural
environment for the benefit of human health and the ecosystem. Research in the
environmental health field tries to limit the harmful exposures through natural things such
as soil, water, air food, etc.
The natural environment encompasses all living and non-living things occurring naturally,
meaning in this case not artificial. The term is most often applied to the Earth or some parts
of Earth. This environment encompasses the interaction of all living species, climate,
weather, and natural resources that affect human survival and economic activity. The
concept of the natural environment can be distinguished as components:
• Complete ecological units that function as natural systems without massive civilized
human intervention, including all vegetation, microorganisms, soil, rocks,
atmosphere, and natural phenomena that occur within their boundaries and their
nature
• Universal natural resources and physical phenomena that lack clear-cut boundaries,
such as air, water, and climate, as well as energy, radiation, electric charge, and
magnetism, not originating from civilized human activity
In contrast to the natural environment is the built environment. In such areas where man
has fundamentally transformed landscapes such as urban settings and agricultural land
conversion, the natural environment is greatly modified into a simplified human
environment. Even acts which seem less extreme, such as building a mud hut or a
photovoltaic system in the desert, modify the natural environment into an artificial one.
Though many animals build things to provide a better environment for themselves, they
are not human, hence beaver dams and the works of Mound-building termites are thought
of as natural.
People seldom find absolutely natural environments on Earth, and naturalness usually
varies in a continuum, from 100% natural in one extreme to 0% natural in the other. More
precisely, we can consider the different aspects or components of an environment, and see
that their degree of naturalness is not uniform.[2] If, for instance, in an agricultural field, the
mineralogic composition and the structure of its soil are similar to those of an undisturbed
forest soil, but the structure is quite different.
The carrying capacity of a biological species in an environment is the maximum population
size of the species that the environment can sustain indefinitely, given the food, habitat,
water, and other necessities available in the environment. In population biology, carrying
capacity is defined as the environment's maximal load,[1] which is different from the
concept of population equilibrium. Its effect on population dynamics may be approximated
in a logistic model, although this simplification ignores the possibility of overshoot which
real systems may exhibit.
Carrying capacity was originally used to determine the number of animals that could graze
on a segment of land without destroying it. Later, the idea was expanded to more complex
populations, like humans. For the human population, more complex variables such as
sanitation and medical care are sometimes considered as part of the necessary
establishment. As population density increases, birth rate often decreases and death rate
typically increases. The difference between the birth rate and the death rate is the "natural
increase". The carrying capacity could support a positive natural increase or could require
a negative natural increase. Thus, the carrying capacity is the number of individuals an
environment can support without significant negative impacts to the given organism and
its environment. Below carrying capacity, populations typically increase, while above, they
typically decrease. A factor that keeps population size at equilibrium is known as a
regulating factor. Population size decreases above carrying capacity due to a range of
factors depending on the species concerned, but can include insufficient space, food supply,
or sunlight. The carrying capacity of an environment may vary for different species and
may change over time due to a variety of factors including: food availability, water supply,
environmental conditions and living space. The origins of the term "carrying capacity" are
uncertain, with researchers variously stating that it was used "in the context of
international shipping" or that it was first used during 19th-century laboratory
experiments with micro-organisms.A recent review finds the first use of the term in an
1845 report by the US Secretary of State to the US Senate.
Section 13.1 Overpopulation
Human overpopulation occurs when the ecological footprint of a human population in a
specific geographical location exceeds the carrying capacity of the place occupied by that
group. Overpopulation can further be viewed, in a long term perspective, as existing when
a population cannot be maintained given the rapid depletion of non-renewable resources
or given the degradation of the capacity of the environment to give support to the
population.[6]
The term human overpopulation refers to the relationship between the entire human
population and its environment: the Earth, or to smaller geographical areas such as
countries. Overpopulation can result from an increase in births, a decline in mortality rates,
an increase in immigration, or an unsustainable biome and depletion of resources. It is
possible for very sparsely populated areas to be overpopulated if the area has a nonexistent capability to sustain life (e.g. a desert). Advocates of population moderation cite
issues like quality of life, carrying capacity and risk of starvation as a basis to argue against
continuing high human population growth and for population decline. Scientists suggest
that the human impact on the environment as a result of overpopulation, profligate
consumption and proliferation of technology has pushed the planet into a new geological
epoch known as the Anthropocene.
Section 13.2 Air Pollution
Air pollution occurs when harmful substances including particulates and biological
molecules are introduced into Earth's atmosphere. It may cause diseases, allergies or death
of humans; it may also cause harm to other living organisms such as animals and food
crops, and may damage the natural or built environment. Human activity and natural
processes can both generate air pollution.
Indoor air pollution and poor urban air quality are listed as two of the world's worst toxic
pollution problems in the 2008 Blacksmith Institute World's Worst Polluted Places report.
According to the 2014 World Health Organization report, air pollution in 2012 caused the
deaths of around 7 million people worldwide, an estimate roughly matched by the
International Energy Agency.
An air quality index (AQI) is a number used by government agencies [1] to communicate to
the public how polluted the air currently is or how polluted it is forecast to become.[2][3] As
the AQI increases, an increasingly large percentage of the population is likely to experience
increasingly severe adverse health effects. Different countries have their own air quality
indices, corresponding to different national air quality standards. Some of these are the Air
Quality Health Index (Canada), the Air Pollution Index (Malaysia), and the Pollutant
Standards Index (Singapore).
Indoor air quality (IAQ) is a term that refers to the air quality within and around buildings
and structures, especially as it relates to the health and comfort of building occupants. IAQ
can be affected by gases (including carbon monoxide, radon, volatile organic compounds),
particulates, microbial contaminants (mold, bacteria), or any mass or energy stressor that
can induce adverse health conditions. Source control, filtration and the use of ventilation to
dilute contaminants are the primary methods for improving indoor air quality in most
buildings. Residential units can further improve indoor air quality by routine cleaning of
carpets and area rugs.
Determination of IAQ involves the collection of air samples, monitoring human exposure to
pollutants, collection of samples on building surfaces, and computer modelling of air flow
inside buildings.
IAQ is part of indoor environmental quality (IEQ), which includes IAQ as well as other
physical and psychological aspects of life indoors (e.g., lighting, visual quality, acoustics,
and thermal comfort).
Indoor air pollution in developing nations is a major health hazard.[2] A major source of
indoor air pollution in developing countries is the burning of biomass (e.g. wood, charcoal,
dung, or crop residue) for heating and cooking.[3] The resulting exposure to high levels of
particulate matter resulted in between 1.5 million and 2 million deaths in 2000.[4]