A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
MAB
Man and Biosphere Program.
macro-floc
the stage of flocculation when large, rapidly settling particles are present.
macroporous
having large pores.
MACT
maximum achievable control technology; controls and procedures required under the CAA Amendments for certain air pollutant sources.
MADCAP
Model of Advection, Diffusion and Chemistry for Air Pollution.
MAER
Maximum Allowable Emission Rate.
maintenance
means the normal operational upkeep to prevent an underground storage tank system from releasing product.
MAJCOM
Major Commands.
major modification
this term is used to define modifications with respect to Prevention of Significant Deterioration and New Source Review under the Clean Air Act and refers to modification to major stationary sources of emissions and provides significant pollution increase levels below which a modification is not considered major.
major stationary sources
term used to determine to applicability of Prevention of Significant Deterioration and new source regulations. In a nonattainment area, any stationary pollutant source that has a potential to emit more than 100 tons per year is considered a major stationary source. In PSD area the cutoff level may be either 100 or 250 tons, depending upon the type of source.
malaise
a feeling of general discomfort, distress, or uneasiness; an out-of-sorts feeling.
management of migration
means actions that are taken to minimize and mitigate the migration of hazardous substances or pollutants or contaminants and the effects of such migration. Measures may include, but are not limited to, management of a plume of contamination, restoration of a drinking water aquifer, or surface water restoration.
manganese greensand
greensand which has been processed to incorporate in its pores and on its surface the higher oxides of manganese.
manufacturers formulation
a list of substances or component parts as described by the maker of a coating, pesticide.
MAP3S
Multistate Atmospheric Power Production Pollution Study.
MARC
Mining and Reclamation Council.
marine sanitation device
any equipment installed on board a vessel to receive, retain, treat, or discharge sewage and any process to treat such sewage.
marsh
a type of wetland that does not accumulate appreciable peat deposits and is dominated by herbaceous vegetation.Marshes may be either fresh or saltwater and tidal or non-tidal.(See: wetlands).
martial law
refers to the temporary emergency powers which can be given to law enforcement personnel, to protect the lives and property of citizens.
masking
blocking out one sight, sound, or smell with another.
matabolite
any substance produced in or by biological processes and derived from a pesticide.
MATC
Maximum Allowable Toxicant Concentration.
material
All types of classifications of chemicals such as products, raw materials, isolated manufacturing intermediates, as well as hazardous and non-hazardous chemicals. Also covered "materials" are items that may normally be considered non-hazardous, but may give off hazardous chemicals during customary and reasonably foreseeable use and misuse, handling and storage; such items are not subject to the article exemption under the OSHA HCS (29 CFR 1910.1200).
material safety data sheet (MSDS)
a compilation of information required under the OSHA Communication Standard on the identity of hazardous chemicals, health, and physical hazards, exposure limits, and precautions. Section 311 of SARA requires facilities to submit MSDSs under certain circumstances.
maximum contaminant level
the maximum permissible level of a contaminant in water delivered to any user of a public water system. MCLs are enforceable standards.
maximum contaminant level goal (MCLG)
this is a number that is associated with no adverse health effects from drinking water containing a particular contaminant over a lifetime. For chemicals believed to cause cancer, for example, the MCLGs are set at zero, as there is no known safe consumption level. It is a non-enforceable, ideal health goal issued as part of the NPDWRs. MCLs are set as close to MCLGs as possible, considering costs and technology.
MBAS
Methylene Blue Active Substance - anionic substances which react with cationically charged methylene blue. The MBAS method is commonly used to detect and quantify anionic surfactants in aqueous systems.
MBDA
Minority Business Development Agency.
MBER
Minority Business Enterprise Representative.
MCA
Manufacturing Chemists Association.
MCC-IP
Materials Characterization Center Static Leach Test.
MCL
Maximum Contaminant Level.
MCLG
Maximum Contaminant Level Goal.
MCP
Municipal Compliance Plan.
MDA
Methylenedianilline.
MDEQ
Massachusetts Department of Environmental Quality.
mechanical aeration
use of mechanical energy to inject air into water to cause a waste stream to absorb oxygen.
mechanical agitation
agitation of a liquid medium through the use of mechanical equipment such as impellers or paddles.
mechanical turbulence
the erratic movement of air caused by local obstructions such as buildings.
media
specific environments-air, water, soil-which are the subject of regulatory concern and activities.
Media Center
refers to a facility staffed by spokespersons from multiple response organizations for the purpose of providing a single designated point of contact with the media and to facilitate exchange of information among spokespersons from different organizations.This type of facility is also referred to as a Joint Public Information Center (JPIC), a Joint Information Center (JIC), or an Emergency News Center (ENC).
MEFR
Maximum Expiratory Flow Rate.
MEI
Maximum Exposed Individual.
melting point
The melting point or freezing point of a pure substance is the temperature at which its crystals are in equilibrium with the liquid phase at atmospheric pressure. The term "melting point" is used when the equilibrium temperature is approached by heating the solid. The terms melting point and freezing point are often used interchangeably, depending on whether the substance Is being heated or cooled.
MEM
Modal Emission Model.
membrane
a barrier, usually thin, that permits the passage only of particles up to a certain size or of special nature.
MEP
Maximum Extent Practicable.
MEP
Multiple Extraction Procedure.
mercury
a heavy metal, highly toxic if breathed or swallowed. It can accumulate in the environment.
MERL
Municipal Environmental Research Laboratory.
MESS
Model Evaluation Support System.
metabolism
the chemical and physical processes whereby the body functions.
metabolize
to convert food, such as soluble organic matter, to cellular matter and gaseous by-products by a biological process.
metal ion
an atom or radical that has lost or gained one or more electrons and has thus acquired an electric charge.Positively charged ions are cations, and those having a negative charge are anions. An ion often has entirely different properties from the element (atom) from which it was formed.
metastasis
the transmission of a disease from one part of the body to another.
meter (m)
a measure of length; 100 cm; the equivalent of 39,371 in.
methane
a colorless, nonpoisonous, flammable gas emitted by marshes and dumps undergoing anaerobic decomposition.
methemoglobinemia
the presence of methemoglobin in the bloodstream caused by the reaction of materials with the hemoglobin in red blood cells that reduces their oxygen-carrying capacity. Methemoglobin is a soluble, brown, crystalline blood pigment that differs from hemoglobin in that it contains ferric iron and is unable to combine reversibly with molecular oxygen.
Method 18
an EPA test method which uses gas chromatographic techniques to measure the concentration of individual volatile organic compounds in a gas stream.
Method 24
an EPA reference method to determine density, water content and total volatile content (water and VOC) of coatings.
Method 25
an EPA reference method to determine the VOC concentration in gas stream.
MFBI
Major Fuel Burning Installation.
MFC
Metal Finishing Category.
mg
milligram (1/1000, 10-3, of a gram).
mg/kg
milligrams per kilogram. Dosage used in toxicology testing to indicate a dose administered per kg of body weight (50 mg = 1 teaspoonful).
mg/m3
milligrams per cubic meter of air. mg/m3 = ppm X MW + 24.45.
mgd
millions of gallons per day. Mgd is a measurement of water flow.
mg/l
Milligrams per Liter.
MH
Man-Hours.
MHD
Magnetohydrodynamics.
MIC
Methyl Isocyanate.
MICE
Management Information Capability for Enforcement.
microbes
Microscopic organisms such as algae, animals, viruses, bacteria, fungus, and protozoa, some of which cause diseases.(See: microorganism).
microbial pesticide
a microorganism that is used to control a pest. They are of low toxicity to man.
micro-floc
the stage of flocculation when small visible particles have started to form.
microgram
one one-millionth of a gram.
micrometer
one one-millionth of a meter; occasionally referred to as a micron.
MICROMORT
A One-in-a-Million Change of Death from and Environmental Hazard.
micron
a linear measure equal to one millionth of a meter, or .00003937 inch. The symbol for the micron is the Greek letter "u".
microorganism
organisms (microbes) observable only through a microscope; larger, visible types are called macroorganisms.
milligrams per liter
this is a weight per volume measurement used in water and wastewater analysis. It is interchangeable with "parts per million" (ppm).
Millimeter (mm)
1/1,000 of a meter.
million-gallons per day (MGD)
a measure of water flow.
mineral
any inorganic or fossilized organic material having a definite chemical composition and structure found in a natural state.
Mine Safety and Health Administration
see MSHA.
MIPR
Military Interagency Procurement Request.
MIS
Management Information System.
miscellaneous oil spill control agent
is any product, other than a dispersant, sinking agent, surface collecting agent, biological additive, or burning agent, that can be used to enhance oil spill cleanup, removal, treatment, or mitigation.
miscible
describes liquids that can be mixed in any ratio.
miscibility
the ability of two liquids, not mutually soluble, to mix.
mist
liquid particles measuring 500 to 40 microns, that are found by condensation of vapor. By comparison, fog particles are smaller than 40 microns.
MITI
Japanese Ministry International Trade & Industry.
mitigation
measures taken to reduce adverse impacts on the environment.
mixed liquor
activated sludge and water containing organic matter being treated in an aeration tank.
mixture
a heterogeneous association of materials that cannot be represented by a chemical formula and that does not undergo chemical change as a result of interaction amongst the mixed materials. The constituent materials may or may not be uniformly dispersed and can usually be separated by mechanical means (as opposed to a chemical reaction). Uniform liquid mixtures are called solutions. "If a hazardous chemical is present in the mixture in reportable quantities (i.e., 0.1% for carcinogens and 1.0% for other health hazards), it must be reported unless the mixture has been tested as a whole" (OSHA CPL 23-02.38A).
ML
Meteorology Laboratory.
ml
Milliliter. A metric unit of capacity equal to 1 cubic centimeter or about 1/16 in3.
MLD
mild irritation effects.
mm Hg
a measure of pressure in millimeters of a mercury column above a reservoir. See atm.
MMI
mucous membrane effects.
MMS
Minerals Management Service.
MOA
Memorandum of Agreement.
mobile source
a moving producer of air pollution, mainly forms of transportation -- cars, motorcycles, planes.
MOD
moderate irritation effects.
model plant
a description of a typical but theoretical plant used for developing economic, environmental impact analyses as support for regulations or regulatory guidelines. It is an imaginary plant, with features of existing or future plants used to estimate the cost of incorporating air pollution control technology as the first step in exploring the economic impact of a potential NSPS.
modeling
an investigative technique using a mathematical or physical representation of a system or theory that accounts for all or some its known properties. Models are often used to test the effect of changes of system components on the overall performance of the system.
MOI
Memorandum of Intent.
moisture content
the water loss of a fully hydrated resin under controlled drying conditions.
mole
a unit weight or volume of a chemical corresponding to its molecular weight. A mole of water weighs 18 g, and its vapor occupies 22.4 L at standard temperature and pressure.
molecular formula
A written representation, using symbols, of a chemical entity. It shows the actual number and kind of atoms in a molecule.
molecular weight
the mass in grams per mole of a substance.See mole.
molecule
the smallest particle of an element or compound retaining its characteristics.
monitoring
periodic or continuous sampling to determine the level of pollution or radioactivity.
monitoring wells
wells drilled at a hazardous waste management facility or Superfund site to collect ground-water samples for the purpose of physical, chemical, or biological analysis to determine the amounts, types, and distribution of contaminants in the ground water beneath the site.
monoclonal antibodies
(Also called MABs and MCAs) molecules of living organisms that selectively find and attach to other molecules to which their structure conforms exactly. This could also apply to equivalent activity by chemical molecules.
monomer
a molecule, usually an organic compound, having the ability to join with a number of identical molecules to form a polymer.
MOS
Margin of Safety.
motor fuel
means petroleum or a petroleum-based substance that is motor gasoline, aviation gasoline, No.1 or No. 2 diesel fuel, or any grade of gasohol, and is typically used in the operation of a motor engine.
MOU
Memoranda of Understanding
MPP
Merit Promotion Plan.
MPPCF
millions of particles per cubic foot of air, based on impinger samples counted by light-field techniques (OSHA).
MPRSA
Marine Protection, Research and Sanctuaries Act.
MPTDS
MPTER Model with Deposition and Settling of Pollutants.
MPTER
Multiple Point Source Model with Terrain.
MRA
Minimum Retirement Age.
MREM
Milliroentgen Equivalent in Man.
MS
Mass Spectrometry.
MSAM
Multi-Keyed Indexed Sequential File Access Method.
MSDS
Material safety data sheet. OSHA has established guidelines for the descriptive data that should be concisely provided on a data sheet to serve as the basis for written hazard-communication programs. The thrust of the law is to have those who make, distribute, and use hazardous materials be responsible for effective communication. See the Hazard Communication Rule, 29 CFR, Pat 1910, 1200, as amended, Section g. See Schedule I, Section 12, of the Canadian Hazardous Products Act.
MSHA
Mine Safety and Health Administration. A Federal agency within the US Department of Labor that devises and promulgates mandatory safety and health rules for mines.
MSK
Muscular-skeletal effects.
MSL
Mean Sea Level.
MSW
Municipal Solid Waste.
MSWL
municipal solid waste landfill.
MSWLF
Municipal Solid Waste Landfill Facility.
MTB
Materials Transportation Bureau.
MTBE
Methyl Tertiary Butyl Ether.
MTD
Maximum Tolerated Dose.
MTDDIS
Mesoscale Transport Diffusion and Deposition Model for Industrial Sources.
MTG
Media Task Group.
MTS
Management Tracking System.
MTSL
Monitoring and Technical Support Laboratory.
MTU
Mobile Treatment Unit.
muck soils
earth made from decaying plant materials.
mucous membrane
the mucous-secreting membrane lining the hollow organs of the body; i.e., nose, mouth, stomach, intestine, bronchial tubes, and urinary tract.
mulch
a layer of material (wood chips, straw, leaves) placed around plants to hold moisture, prevent weed growth, and enrich soil.
multiple use
harmonious use of land for more than one purpose; i.e., grazing of livestock, wildlife production, recreation, watershed and timer production. Not necessarily the combination of uses that will yield the highest economic return or greatest unit output.
MUT, Mutagen
a material that induces genetic changes (mutations) in the DNA of chromosomes. Chromosomes are the "blueprints" of life within individual cells.
mutagen
any substance that causes changes in the genetic structure in subsequent generations.
mutate
to bring about a change in the genetic constitution of a cell by altering its DNA. In turn, "mutagenesis" is any process by which cells are mutated.
mutual aid agreement
refers to an agreement between two or more jurisdictions or between a jurisdiction and one or more private entities in which the signatories promise to come to provide assistance to each other when such assistance is requested.
MVA
Multivariate Analysis.
MVAPCA
Motor Vehicle Air Pollution Control Act.
MVEL
Motor Vehicle Emissions Laboratory.
MV/M
Motor Vehicle Inspection/Maintenance.
MVL
Maximum Use Limits.
MVRS
Marine Vapor Recovery System.
MVV
Maximal Voluntary Ventilation.
MW
see Molecular Weight.
MW
Megawatt.
MWC
Municipal Waste Combustor.
MWL
Municipal Waste Leachate.
MWTA
Medical Waste Treatment Act.
