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| particulate matter with an average diameter of 10 um or less |
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| particulate matter with an average diameter less than 2.5 um, also called fine particles. |
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| a millionth(10^-6) of a meter sometimes simply refered to as a micron. |
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| air pollutants for which EPA has set permissible levels based on their effects on human health and on the environment |
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physical combination of two or more substances present in variable amounts
(See page(s) 11) |
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Definition
parts per hundred; sometimes abbreviated as pph
(See page(s) 11, 201) |
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Definition
1 part out of a million parts, unit of concentration. 1 ppm is 10,000 times less concentrated than 1 part per hundred (pph).
(See page(s) 13, 201) |
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Definition
organized evaluation of scientific data to predict the probability of an occurrence
(See page(s) 17) |
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Definition
intrinsic health hazard of a substance
(See page(s) 17) |
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Definition
amount of a substance encountered, generally in reference to human contact with a toxic substance or a disease-causing organism
(See page(s) 17) |
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Definition
a millionth (10-6) of a gram
(See page(s) 18) |
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Definition
the outside air, that is, the air surrounding or encircling us
(See page(s) 18) |
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Definition
1 part out of a billion parts, unit of concentration. 1 ppb is 1000 times less concentrated than 1 ppm.
(See page(s) 19, 202) |
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Definition
region of the atmosphere that lies directly above the surface of the Earth
(See page(s) 20) |
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Definition
region of the atmosphere above the troposphere; includes the ozone layer
(See page(s) 20) |
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Definition
region of the atmosphere above the stratosphere; found at an altitude starting about 50 km
(See page(s) 20) |
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Definition
pure substance that cannot be broken down into simpler ones by any chemical means
(See page(s) 21) |
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Definition
one- or two-letter abbreviation for an element. Also called atomic symbol
(See page(s) 21) |
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Definition
an orderly arrangement of all the elements based on similarities in their properties
(See page(s) 22) |
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Definition
vertical column in the periodic table
(See page(s) 23) |
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Definition
elements that are shiny and conduct electricity and heat well. They tend to lose their valence electrons to form cations.
(See page(s) 23, 210) |
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Term
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Definition
elements with varied appearances that do not conduct electricity or heat well. Nonmetals tend to gain electrons to form anions.
(See page(s) 23, 210) |
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Term
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Definition
elements between metals and nonmetals on the periodic table that do not fall cleanly into either group. Sometimes called semimetals.
(See page(s) 23) |
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Definition
elements that are inert and do not readily undergo chemical reactions
(See page(s) 24) |
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pure substance made up of two or more elements in a fixed, characteristic chemical combination
(See page(s) 24) |
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smallest unit of an element that can exist as a stable, independent entity
(See page(s) 25) |
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technology at the atomic and molecular (nanometer) scale: 1 nanometer (nm) =1 ×10-9 m
(See page(s) 25) |
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Definition
two or more atoms held together by chemical bonds in a certain spatial arrangement
(See page(s) 26) |
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Definition
symbolic way to represent the elementary composition of a substance, indicating the kinds and numbers of atoms present in a molecule
(See page(s) 26, 408) |
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molecule that contains two atoms
(See page(s) 26) |
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compound that contains only the elements hydrogen and carbon
(See page(s) 28, 171) |
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Definition
chemical process in which a fuel combines rapidly with oxygen to release energy and form products
(See page(s) 29,158) |
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Definition
process whereby reactants are transformed into products
(See page(s) 29) |
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starting material that is transformed into a product during a chemical reaction
(See page(s) 29) |
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substance formed from reactants as a result of a chemical reaction
(See page(s) 29) |
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representation of a chemical reaction using chemical formulas
(See page(s) 29) |
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| law of conservation of matter and mass |
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Definition
in a chemical reaction, matter and mass are conserved
(See page(s) 30) |
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Definition
particles, both liquid and solid, that remain suspended in the air rather than settling out
(See page(s) 35) |
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device installed in the exhaust stream of an engine to reduce emissions
(See page(s) 36) |
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Definition
chemical substance that participates in a chemical reaction and influences its rate or speed without undergoing permanent change
(See page(s) 36, 84) |
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Definition
refers to a substance that readily passes into the vapor phase
(See page(s) 36) |
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Definition
compound that contains mainly carbon and hydrogen
(See page(s) 36) |
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Term
| volatile organic compounds (VOCs) |
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Definition
vapors of incompletely burned gasoline molecules or fragments of these molecules
(See page(s) 37) |
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Definition
the designing of chemical products and processes that reduce or eliminate the use or generation of hazardous substances
(See page(s) 38) |
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Definition
pollutant produced from chemical reactions among two or more other pollutants
(See page(s) 40) |
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Definition
capable of causing cancer
(See page(s) 43) |
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a number that correctly represents the accuracy with which an experimental quantity is known
(See page(s) 46) |
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