Six "criteria pollutants" (ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, particulate matter, and lead) US EPA uses to indicate air quality. US EPA has established for each of them a maximum concentration above which adverse effects on human health may occur. These threshold concentrations are called National Ambient Air Quality Standards.

The homologous group of linear saturated aliphatic hydrocarbons having the general formula C(n)H(2n+2). Alkanes can be straight or branched chains or ring structures. Also called paraffins.

Chronic respiratory system disorder characterized by wheezing, coughing, and difficulty in breathing.

One stock tank barrel of oil or natural gas liquids, with volumes expressed in standard 42 US gallon barrels or 34.972 Imperial gallon barrels.

An inflammation of the mucous lining of the bronchial tubes.

A compound or material capable of producing cancer.

An estimated daily exposure level for the human population, including sensitive sub-populations, likely to be without an appreciable risk of deleterious effects over the long term (seven years to a lifetime).

Multi-national military force assembled and aligned to remove the occupation forces of the Republic of Iraq from Kuwait.

The amount of a substance available for interaction with metabolic processes or biologically significant receptors after crossing an organism’s outer boundary. Dose is a function of the concentration of the substance to which a receptor is exposed and exposure duration.
Potential dose: The amount ingested, inhaled, or applied to the skin.
Applied dose: The amount of a substance presented to an absorption barrier and available for absorption (although not necessarily having yet crossed the outer boundary of the organism).
Absorbed dose: The amount crossing a specific absorption barrier (e.g., the exchange boundaries of skin, lung and digestive tract) through uptake.
Internal dose: A more general term denoting the amount absorbed without respect to specific absorption barriers or exchange boundaries.
Delivered dose (for an organ or cell): The amount of a chemical available for interaction by any particular organ or cell.

The probability an individual will acquire cancer over a lifetime of exposure. US EPA has determined the acceptable range of excess cancer as one in a population of 10,000 to one in a population of 1,000,000 under conditions of exposure. Regulatory agencies often use a risk level, or probability of one in 1,000,000 an individual could develop cancer due to an exposure to potential carcinogens at a site, as the point of departure to trigger action.

Contact with a chemical or physical agent, quantified as the agent’s concentration in the medium in contact integrated over the time duration of that contact.

The determination or estimation (qualitative or quantitative) of the magnitude, frequency, duration, route, and extent (number of people) of exposure to a chemical.

The course a contaminant takes from the source to the exposed person, generally consisting of four elements: 1) source of chemical release; 2) receiving and/or transporting medium (e.g., air, soil, water); 3) point of potential contact; and 4) exposure route (e.g., inhalation, ingestion, dermal contact).

The sum of more than one hazard quotient for several substances and/or several exposure pathways, calculated separately for chronic, sub-chronic, and shorter duration exposures.

The ratio of a single substance exposure level over a specified time period (e.g., sub-chronic) to a reference dose for that substance derived from a similar exposure period.

Metallic elements with high atomic weights, e.g., mercury, chromium, cadmium, arsenic, and lead. They can cause damage to living organisms at very low concentrations and tend to accumulate in the food chain.

A qualitative or quantitative evaluation of the environmental health risk resulting from exposure to a chemical or physical agent (pollutant); combines exposure assessment results with toxicity assessment results to estimate risk.

A highly toxic, highly flammable, heavier-than-air gas present in crude oil; normally removed during the refining process.

The rate by which a substance crosses an organism’s outer boundary without passing an absorption barrier, e.g., through ingestion or inhalation.

The isolation of a pollutant plume aloft, occurring when the plume is emitted or disperses to a position above a stable layer or temperature inversion lid that inhibits downward dispersion and isolates the plume from lower layers near the ground.

A regional oil-bearing geologic structure 12,000 to 14,000 feet deep below the earth’s surface.

Using mathematical methods to simulate processes to predict results. In the context of exposure assessment, any mathematical method describing a physical system used to predict the concentration of specific chemicals as a function of space and time subject to transport, intermedia transfer, storage, and degradation in the environment.

Mission Oriented Protective Posture (MOPP) is a flexible system used to direct the wearing of chemical protective garments and mask – a system that balances mission requirements with the chemical warfare agent threat. Wearing chemical protective garments and mask provides soldiers protection against most know chemical warfare agents, biological agents, and toxins.

At MOPP Level 0 soldiers carry their protective mask while their remaining MOPP gear must be readily available (e.g., within the work area, fighting position, living space, etc.). At MOPP Level 1, soldiers wear their overgarment and carry the rest of their MOPP gear. At MOPP Level 2, soldiers wear their overgarment and overboots while carrying the mask with hood and gloves. At MOPP Level 3, soldiers wear their overgarment, overboots, and mask with hood, but not the gloves. At MOPP Level 4, soldiers wear all their MOPP gear. Commanders can raise or lower the amount of protection through five levels of MOPP. In addition, commanders, under certain situations, can exercise a mask-only option.