Basic Calculations for Occupational Safety and Environmental Health Professionals - Mathematics and Statistics for the Environment - page 385

Acute toxicity —The discernible adverse effects induced in an organism within a short period
of time (days) of exposure to an agent.
Adsorption —The taking up of a gas or liquid at the surface of another substance, usually a
solid (e.g., activated charcoal adsorbs gases).
Aerosols —Liquid or solid particles so small they can remain suspended in air long enough to
be transported over a distance.
Air contamination —The result of introducing foreign substances into the air so as to make
the air contaminated.
Air pollution —Contamination of the atmosphere (indoor or outdoor) caused by the discharge
(accidental or deliberate) of a wide range of toxic airborne substances.
Air sampling —Safety engineers are interested in knowing what contaminants workers are
exposed to and the contaminant concentrations. Determining the quantities and types of
atmospheric contaminants is accomplished by measuring and evaluating a representative
sample of air. The types of air contaminants that occur in the workplace depend upon the
raw materials used and the processes employed. Air contaminants can be divided into
two broad groups, depending upon physical characteristics: (1) gases and vapors, and (2)
particulates.
Allergens —Because of the presence of allergens on spores, all molds studied to date have the
potential to cause allergic reaction in susceptible people. Allergic reactions are believed to
be the most common exposure reaction to molds (Rose, 1999).
Ambient —Descriptive of any condition of the environment surrounding a given point. For
example, ambient air means that portion of the atmosphere, external to buildings, to which
the general public has access. Ambient sound is the sound generated by the environment.
Asphyxiation —Suffocation from lack of oxygen. A substance (e.g., carbon monoxide) that
combines with hemoglobin to reduce the blood's capacity to transport oxygen produces
chemical asphyxiation. Simple asphyxiation is the result of exposure to a substance (such
as methane) that displaces oxygen.
Atmosphere —In physics, a unit of pressure whereby 1 atmosphere (atm) equals 14.7 pounds
per square inch (psi).
Attenuation —The reduction of intensity at a designated first location as compared with inten-
sity at a second location farther from the source (reducing the level of noise by increasing
distance from the source is a good example).
Audible range —The frequency range over which normal hearing occurs—approximately 20
Hz through 20,000 Hz. Above the range of 20,000 Hz, the term ultrasonic is used. Below
20 Hz, the term subsonic is used.
Audiogram —A record of hearing loss or hearing level measured at several different frequen-
cies, usually 500 to 6000 Hz. The audiogram may be presented graphically or numerically.
Hearing level is shown as a function of frequency.
Audiometric testing —Objective measuring of a person's hearing sensitivity. By recording the
response to a measured signal, a person's level of hearing sensitivity can be expressed in
decibels, as related to an audiometric zero, or no-sound base.
Authorized person —A person designated or assigned by an employer or supervisor to per-
form a specific type of duty or duties, to use specified equipment, or to be present in a
given location at specified times (e.g., an authorized or qualified person is used in confined
space entry).
Auto-ignition temperature —The lowest temperature at which a vapor-producing substance or
a flammable gas will ignite even without the presence of a spark or flame.
Baghouse —Term commonly used for the housing containing bag filters for recovery of fumes
from arsenic, lead, sulfa, etc.
Baseline data —Data collected prior to a project for later use in describing conditions before
the project began. Also commonly used to describe the first audiogram given (within 6