Basic Calculations for Occupational Safety and Environmental Health Professionals - Mathematics and Statistics for the Environment - page 387

employees as required by particular OSHA regulations under the conditions to which such
regulations apply.
Confined space —A vessel, compartment, or any area having limited access and (usually)
no alternative escape route, having severely limited natural ventilation or an atmosphere
containing less that 19.5% oxygen, and having the capability of accumulating a toxic, flam-
mable, or explosive atmosphere, or of being flooded (engulfing a victim).
Containment —In fire terminology, restricting the spread of fire. For chemicals, restricting
chemicals to an area that is diked or walled off to protect personnel and the environment.
Contingency plan ( emergency response plan )—Under 40 CFR 260.10, a document that sets
forth an organized, planned, and coordinated course of action to be followed in the event
of an emergency that could threaten human health or the environment.
Convection —The transfer of heat from one location to another by way of a moving medium,
including air and water.
Corrosive material —Any material that dissolves metals or other materials or that burns the
skin.
Cumulative injury —Any physical or psychological disability that results from the combined
effects of related injuries or illnesses in the workplace.
Cumulative trauma disorder —A disorder caused by the highly repetitive motion required of
one or more parts of a worker's body, which in some cases, can result in moderate to total
disability.
Dalton's law of partial pressures —In a mixture of theoretically ideal gases, the pressure
exerted by the mixture is the sum of the pressures exerted by each component gas of the
mixture.
Decibel (dB) —A unit of measure used originally to compare sound intensities and subse-
quently electrical or electronic power outputs; now also used to compare voltages. In hear-
ing conservation, it is a logarithmic unit used to express the magnitude of a change in level
of sound intensity.
Decontamination —The process of reducing or eliminating the presence of harmful sub-
stances such as infectious agents, to reduce the likelihood of disease transmission from
those substances.
Density —A measure of the compactness of a substance; it is equal to its mass per unit volume
and is measured in kilogram per cubic meter or pounds per cubic foot (Density = Mass/
Volu me).
Dermatitis —Inlammation or irritation of the skin from any cause. Industrial dermatitis is an
occupational skin disease.
Design load —The weight that can be safely supported by a floor, equipment, or structure, as
defined by its design characteristics.
Dike —An embankment or ridge of either natural or manmade materials used to prevent the
movement of liquids, sludges, solids, or other materials.
Dilute —Adding material to a chemical by the user or manufacturer to reduce the concentra-
tion of active ingredient in the mixture.
Dose —An exposure level. Exposure is expressed as weight or volume of test substance per
volume of air (mg/L), or as parts per million (ppm).
Dosimeter —Measuring tool that provides a time-weighted average over a period of time such
as one complete work shift.
Dusts —Various types of solid particles produced when a given type of organic or inorganic
material is scraped, sawed, ground, drilled, heated, crushed, or otherwise deformed.
Electrical grounding —Precautionary measures designed into an electrical installation to
eliminate dangerous voltages in and around the installation and to operate protective
devices in case of current leakage from energized conductors to their enclosures.