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object for flood protection
occupational accident

work-related accident. Occupational accidents that injure employees are the responsibility of the employer and are covered by Workers Compensation Insurance. In recent years, the term occupational accident has been expanded to include job-related long-term exposure to hazardous substances that result in occupational diseases, and such emotional injuries as nervous breakdowns and even heart attacks.

occupational disease

disease or disability resulting from conditions of employment, usually from long exposure to a noxious substance or from continuous repetition of certain acts.

A disease or an ailment caused due to excessive exposure of noxious fumes or substances in a working environment that are injurious to health. It includes asthma, poisoning due to use of pesticides, black lung disease among miners, lung cancer due to use of asbestos and other respiratory problems. Any employee who gets affected by disease or a disability under such condition is liable to receive compensation under the laws of workmen's compensation or any other related provision.

occupational environment

occupational environment is the physical surroundings and social environment at a workplace. The risk of occupational environment is 1−3 order of magnitude more than the risk of non-occupational environment.
occupational hazards − any condition of a job that can result in illness or injury − are summarized here: workplace hazard groups

Occupational Exposure Limit (OEL)
occupational health

occupational health and safety is a cross-disciplinary area concerned with protecting the safety, health and welfare of people engaged in work or employment. The goal of all occupational health and safety programs is to foster a safe work environment.

As a secondary effect, it may also protect co-workers, family members, employers, customers, suppliers, nearby communities, and other members of the public who are impacted by the workplace environment. It may involve interactions among many subject areas, including occupational medicine, occupational (or industrial) hygiene, public health, safety engineering, chemistry, health physics.

occupational health and safety (OSH)

the occupational health and safety low, organisations and officiers promote health and safety procedures in an organisation. They recognize hazards and measure health and safety risks, set suitable safety controls in place, and give recommendations on avoiding accidents to management and employees in an organisation.

Since 1950, the International Labour Organization (ILO) and the World Health Organization (WHO) have shared a common definition of occupational health. It was adopted by the Joint ILO/WHO Committee on Occupational Health at its first session in 1950 and revised at its twelfth session in 1995. The definition reads: "Occupational health should aim at: the promotion and maintenance of the highest degree of physical, mental and social well-being of workers in all occupations; the prevention amongst workers of departures from health caused by their working conditions; the protection of workers in their employment from risks resulting from factors adverse to health; the placing and maintenance of the worker in an occupational environment adapted to his physiological and psychological capabilities; and, to summarize, the adaptation of work to man and of each man to his job."

occupational injury

an accident at work is defined as an external, sudden, unexpected, unintended, during the execution of work or arising out of it, which may lead to an industrial injury and /or fatality and /or material and /or environmental damages.The accident is a preceding "event" while the resulting damage,be it injury, fatality, material or environmental damages are all consequences of this event.

Where the accidents involve multiple fatalities they are often referred to as industrial disasters.

An industrial injury is bodily damage resulting from working.

The most usual organs involved are the spine, hands, the head, lungs, eyes, skeleton, and skin. According to data from the National Institute for Occupational Safety and Health and the Bureau of Labor Statistics, an average of 15 workers die from traumatic injuries each day in the United States, and an additional 200 workers are hospitalized.

Common causes of industrial injury are poor ergonomics, manual handling of heavy loads, misuse or failure of equipment, exposure to general hazards, inadequate safety training and clothing, jewellery or long hair that becomes tangled in machinery.

General hazards in a work environment include electricity, explosive materials, fire, flammable gases, heat, height, high pressure gases and liquids, hot gases and liquids, powerful or sharp moving machinery, oxygen-free gases or spaces, poisonous gases, radiation, toxic materials, work on, near or under water, work on, near or under weak or heavy structures.

There are many methods of preventing or reducing industrial injuries, including anticipation of problems by risk assessment, safety training, control banding, personal protective equipment safety guards, mechanisms on machinery, and safety barriers. In addition, past problems can be analyzed to find their root causes by using a technique called root cause analysis.

Source: http://en.wikipedia.org/wiki/Industrial_injury

occupational safety

occupational safety means low risk at working environment, saftey physical and social conditions at a workplace.

occupational safety criteria
occupational toxicology

occupational toxicology – sometimes also called industrial toxicology is dealing with (potential) toxic effects at workplaces on workers. Aim of occupational risk management to protect workers from physical agents and chemical substances and makes their work-environment safe. It means that it is closely related to environmental toxicology, but “environment” is restricted to the workplace: the air inside the industrial plant, the risk of dermal or eye contact of chemical substances being at work, as well as development of occupational diseases in association with the chemical substances used or produced in the technologies.

octane number

called also octane rating, a value used to indicate the resistance of a motor fuel to knock, measure of the ignition quality of gas (gasoline or petrol). octane numbers are based on a scale on which isooctane is 100 (minimal knock) and n-heptane is 0 (bad knock). A gasoline with an octane number of 98 has the same knock as a mixture of 98% isooctane and 2% n-heptane.

octanol-water partition coefficient

The number of odour units per unit of volume. The numeric value of the odour concentration, expressed in odour units ( E/ m3 ) equals the number of times that the air should be treated with odourless air to reach the odour threshold.

A standard for odour, expressed as a maximum concentration, which may not be crossed.

Odour treshold is the concentration of a gaseous substance, expressed in µg/m3, which will be discerned from odourless air by at least half of an odour panel. The odour threshold per definition has an odour concentration of 1 odour unit/ m3.

Serious odour nuisance is the degree of odour nuisance which exceeds the maximum admittable level for human health. Both health effects and personally experienced effects play a part here. In practise a level of odour nuisance is determined by questionnaires in which people can describe the degree of odour nuisance they have experienced.


our sensibility for the odour of a substance is expressed as a threshold value. This is the concentration of a substance in 1 m3 air that can be detected by half of the people that are present. This is considered the unit of odour.
- Chloroform is detected when 130 molecules are present in a million molecules of air.
- Chlorophenols can already be detected when 3 molecules are present in a hundred billion molecules of air.
Humans can differ up to a factor of a hundred thousand in their sensibility for a certain substance.

Source: http://www.lenntech.com/odour-information.htm

oil spill
oil-sorbing capacity of the soil
See: alkene.
omega-3 fatty acids

n-3 fatty acids ω-3 fatty acids or omega-3 fatty acids are a family of unsaturated fatty acids that have a double bond in the n-3 position; that is, the third bond from the methyl end of the fatty acid.

They are nutritionally important fatty acids including α-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid, which are polyunsaturated fatty acids. The synthesis of omega-3 fatty acids is very slow, or does not exist at all in human body, so that it is more effective to take it up directly from food.

on site soil remediation

a gene, one or more forms of which is associated with cancer. Many oncogenes are involved, directly or indirectly, in controlling the rate of cell growth.

one component substance, REACH
operating noise or vibration source
operator of ambient noise or a vibration source

a set of genes transcribed under the control of an operator gene.

organic pollutants
organic solvent input in the legal regulation of the air
organic solvent use in the legal regulation of the air
organic weed management

organic weed management promotes weed suppression, rather than weed elimination, by enhancing crop competition and phytotoxic effects on weeds. Organic farmers integrate cultural, biological, mechanical, physical and chemical tactics to manage weeds without synthetic herbicides.

Organic crop rotations frequently include weed-suppressive cover crops and crops with dissimilar life cycles to discourage weeds associated with a particular crop. Organic farmers strive to increase organic soil matter content, which can support microorganisms that destroy common weed seeds.

Other cultural practices used to enhance crop competitiveness and reduce weed pressure include selection of competitive crop varieties, high-density planting, tight row spacing, and late planting into warm soil to encourage rapid crop germination.

Mechanical and physical weed control practices used on organic farms can be broadly grouped as

  • Tillage - turning the soil between crops to incorporate crop residues and soil amendments; remove existing weed growth and prepare a seedbed for planting;
  • Cultivation - disturbing the soil after seeding;
  • Mowing and cutting - removing top growth of weeds;
  • Flame weeding and thermal weeding - using heat to kill weeds; and
  • Mulching - blocking weed emergence with organic materials, plastic films, or landscape fabric.

Some naturally-sourced chemicals are allowed for herbicidal use. These include certain formulations of acetic acid (concentrated vinegar), corn gluten meal, and essential oils. A few selective bioherbicides based on fungal pathogens have also been developed. At this time, however, organic herbicides and bioherbicides play a minor role in the organic weed control toolbox.

Weeds can be controlled by grazing. For example, geese have been used successfully to weed a range of organic crops including cotton, strawberries, tobacco, and corn, reviving the practice of keeping cotton patch geese, common in the southern U.S. before the 1950s. Similarly, some rice farmers introduce ducks and fish to wet paddy fields to eat both weeds and insects.

Organisation for Economic Cooperation and Development (OECD)

occupational safety and health, see occupational health and safety (OSH)


United States Department of Labor, Occupational Safety and Health Administration.

Safety and Health Topics Pages provide access to selected occupational safety and health information. The subjects of these pages include specific workplace hazards, as well as individual industries. Members of the Editorial Boards evaluate numerous OSHA and non-OSHA references on a given subject to determine which they consider most important in reducing occupational injuries and illnesses. With the continued support of our users, editors, and editorial boards, OSHA's Safety and Health Topics Pages provide assistance for complying with OSHA standards, enabling employers to ensure safer workplaces.

Source: http://www.osha.gov/index.html


the United States Occupational Safety and Health Administration (OSHA) is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970.

Its mission is to prevent work-related injuries, illnesses, and occupational fatality by issuing and enforcing standards for workplace safety and health. The agency is headed by a Deputy Assistant Secretary of Labor.

The OSH Act, which created OSHA also created the National Institute for Occupational Safety and Health (NIOSH) as a research agency focusing on occupational health and safety. NIOSH, however, is not a part of the U.S. Department of Labor.

OSHA federal regulations cover most private sector workplaces. The OSH Act permits states to develop approved plans as long as they cover public sector employees and they provide protection equivalent to that provided under Federal OSHA regulations. In return, a portion of the cost of the approved state program is paid by the federal government.

output flows, LCA
oxidising properties
while in themselves not necessarily combustible, substances with oxidising properties may cause or contribute to the combustion of other material. These properties tests are designed to allocate an oxidising substance into the appropriate hazard class by comparison to one or more reference substance(s). (http://www.prc.cnrs-gif.fr/reach/en/physicochemical_data.html) The study does not need to be conducted if the substance is explosive; or the substance is highly flammable; or the substance is an organic peroxide; or the substance is incapable of reacting exothermically with combustible materials, for example on the basis of the chemical structure (e.g. organic substances not containing oxygen or halogen atoms and these elements are not chemically bonded to nitrogen or oxygen, or inorganic substances not containing oxygen or halogen atoms).

an oxidizer or an oxidizing agent, also called oxidant, can be defined asa chemical compound that readily transfers oxygen atoms, or a substance that gains electrons in a redox chemical reaction. In both cases, the oxidizing agent becomes reduced in the process.

The dangerous substance definition of an oxidizer is a substance that is not necessarily combustible, but may, generally by yielding oxygen, cause or contribute to the combustion of other material. By this definition some materials that are classified as oxidizing agents by analytical chemists or biochemists are not classified as oxidizing agents in a dangerous materials sense.

Oxidising, literally, means converting to oxide. This process can apply to metals (iron converts to iron oxide), nonmetals (sulfur converts to sulfur oxide), and organic matter (mainly carbon and hydrogen converts to carbon oxide and hydrogen oxide). An obvious oxidizer is oxygen, which forms about 21% of air.

Later, the use of the term expanded to include any time where formal charge is increased (losing electrons), and applies to substances which contain no oxygen (typically halogens and substances rich in these elements, and less commonly sulfur). Oxidising is the opposite of reduction, where formal charge is decreased (gaining electrons). Redox reactions occur when oxidation states of the reactants change. In a redox-system the oxidizing agent is reduced, the reducing agent is oxidized. All atoms in a molecule can be assigned an oxidation number. This number changes when an oxidant acts on a substrate.

Many common oxidizers contain oxygen (KClO4 is KCl "plus" 2 O2) and can be considered compact storage of oxygen; a given volume of potassium perchlorate contains much more oxygen than the same volume of air.The most common oxidizers are the following:

Ammonium cerium(IV) nitrate and probably related cerium(IV) compounds
Chlorite, chlorate, perchlorate, and other analogous halogen compounds
Hexavalent chromium compounds such as chromic and dichromic acids and chromium trioxide, pyridinium chlorochromate (PCC), and chromate/dichromate compounds
Hypochlorite and other hypohalite compounds such as bleach
Iodine and other halogens
Nitric acid
Nitrous oxide (N2O)
Osmium tetroxide (OsO4)
Permanganate salts
Peroxide compounds
Persulfuric acid
Potassium nitrate (KNO3)
Sulfuric acid
Tollens' reagent: ammoniacal silver nitrate

Source: http://en.wikipedia.org/wiki/Oxidizing_agent


oxidizing liquid

a liquid which, while in itself not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other material.

oxigene consumption
oxigene demand

oxygen is an element, its atomic number is 8 and represented by the symbol O. It is a member of the chalcogen group on the periodic table, and is a highly reactive nonmetallic period 2 element that readily forms compounds (notably oxides) with almost all other elements. At standard temperature and pressure, two atoms of the element bind to O2 molecule, a colorless, odorless, tasteless gas . Oxygen is the third most abundant element in the universe by mass after hydrogen and helium and the most abundant element by mass in the Earth's crust. Oxygen constitutes 49.2% of the Earth's crust by mass and is the major component of the world's oceans (88.8% by mass). Oxygen gas is the second most common component of the Earth's atmosphere, taking up 21.0% of its volume and 23.1% of its mass (some 1015 tonnes). Earth is unusual among the planets of the Solar System in having such a high concentration of oxygen gas in its atmosphere: Mars (with 0.1% O2 by volume) and Venus have far lower concentrations. However, the O2 surrounding these other planets is produced solely by ultraviolet radiation impacting oxygen-containing molecules such as carbon dioxide.

All major classes of structural molecules in living organisms, such as proteins, carbohydrates, and fats, contain oxygen, as do the major inorganic compounds that comprise animal shells, teeth, and bone. Oxygen in the form of O2 is produced from water by cyanobacteria, algae and plants during photosynthesis and is used in cellular respiration for all complex life. Oxygen is toxic to obligately anaerobic organisms, which were the dominant form of early life on Earth until O2 began to accumulate in the atmosphere 2.5 billion years ago.

Another form of oxygen, ozone (O3), helps protect the biosphere from ultraviolet radiation with the high-altitude ozone layer, but is a pollutant near the surface where it is a by-product of smog. At even higher low earth orbit altitudes atomic oxygen is a significant presence and a cause of erosion for spacecraft.



The unusually high concentration of oxygen gas on Earth is the result of the oxygen cycle. This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere. The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere. Photosynthesis releases oxygen into the atmosphere, while respiration and decay remove it from the atmosphere. In the present equilibrium, production and consumption occur at the same rate of roughly 1/2000th of the entire atmospheric oxygen per year.

Free oxygen also occurs in solution in the world's water bodies. The increased solubility of O2 at lower temperatures has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content. Polluted water may have reduced amounts of O2 in it, depleted by decaying algae and other biomaterials (eutrophication). Scientists assess this aspect of water quality by measuring the water's biochemical oxygen demand, or the amount of O2 needed to restore it to a normal concentration.

In nature, free oxygen is produced by the light-driven splitting of water during oxygenic photosynthesis. Green algae and cyanobacteria in marine environments provide about 70% of the free oxygen produced on earth and the rest is produced by terrestrial plants.

A simplified overall formula for photosynthesis is:

6 CO2 + 6 H2O + photons → C6H12O6 + 6 O2 (or simply carbon dioxide + water + sunlight → glucose + dioxygen)

Photolytic oxygen evolution occurs in the thylakoid membranes of photosynthetic organisms and requires the energy of four photons. Many steps are involved, but the result is the formation of a proton gradient across the thylakoid membrane, which is used to synthesize ATP via photophosphorylation. The O2 remaining after oxidation of the water molecule is released into the atmosphere.

Molecular dioxygen, O2, is essential for cellular respiration in all aerobic organisms. Oxygen is used in mitochondria to help generate adenosine triphosphate (ATP) during oxidative phosphorylation. The reaction for aerobic respiration is essentially the reverse of photosynthesis and is simplified as:

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 2880 kJ·mol-1

In vertebrates, O2 is diffused through membranes in the lungs and into red blood cells. Hemoglobin binds O2, changing its color from bluish red to bright red. Other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters). A liter of blood can dissolve 200 cm3 of O2.

An adult human in rest inhales 1.8 to 2.4 grams of oxygen per minute.This amounts to more than 6 billion tonnes of oxygen inhaled by humanity per year. (Source: Wikipedia)

An aerobic environment is characterized by the presence of free oxygen (O2) while an anaerobic environment lacks free oxygen but may contain atomic oxygen bound in compounds such as nitrate (NO3), nitrite (NO2), and sulfites (SO3). Aerobe organisms, including microbes require O2 as their terminal electron acceptor, but anaerobe microbes use a bound form of oxygen instead. There is by definition a byproduct of anaerobic decomposition − the non-oxygen element must go somewhere when the oxygen atom is biochemically removed by the microbe. When sulfites are present, the byproduct is hydrogen sulfide, a foul smell corrosive gas. When nitrites/nitrates are present, the byproduct is inert nitrogen gas.

Most microbes in wastewaters, in deeper waters and soil layers are facultative. That is in the presence of oxygen they act as aerobes, and in the absence of oxygen they act as anaerobes even if bound oxygen is present in large amounts. Aerobic respiration is favored, because the biochemical pathway using O2 provides a much higher oxidation/reduction potential and is energetically favored.

The free or bound oxygene contentsof the environment can be characterised by the redoxpotential, a measure in volts, which gives the affinity of a substance or an environment for electrons compared with hydrogen, which has a redoxpotential of zero (0).


ethers or alcohols added to gasoline to enhance the octane number and reduce CO production. The most widely used oxygenate is methyl tert-butyl ether (MTBE) produced from methanol and isobutylene. They are water-soluble resulting in fast spreading with groundwater after leaching.

ozone shield

a layer of the atmosphere composed of ozone gas (O3) that resides approximately 25 miles above the Earth's surface and absorbs solar ultraviolet radiation that can be harmful to living organisms.