AHMM key terms

Any substance or material capable of posing an unreasonable risk to health, safety, or property when transported, stored, handled, or used, as defined by the applicable regulatory framework.

Discarded material that is specifically listed as hazardous or that exhibits ignitability, corrosivity, reactivity, or toxicity, and is therefore subject to cradle-to-grave management requirements.

A grouping of materials sharing a dominant physical or health hazard, such as flammable liquid, oxidizer, toxic, or corrosive, used to drive labeling, segregation, and emergency response decisions.

A subdivision within a hazard class that separates materials by degree or type of hazard, for example dividing explosives into compatibility groups or gases into flammable and nonflammable subcategories.

A three-tier ranking (I, II, III) assigned to certain hazardous materials reflecting the degree of danger they present, with Group I representing great danger and Group III minor danger.

A four-digit identification code assigned internationally to a specific hazardous substance or article, used on shipping papers, labels, and placards to speed recognition during transport and emergencies.

A standardized sixteen-section document providing hazard, composition, first-aid, firefighting, handling, storage, exposure control, and disposal information for a chemical product.

An internationally agreed framework for classifying chemicals and communicating hazards through standardized pictograms, signal words, hazard statements, and precautionary statements on labels and data sheets.

The regulatory program requiring employers to inform and train workers about chemical hazards in their workplace through labels, safety data sheets, and written training programs.

A graphic symbol on a diamond-shaped border that conveys a specific hazard type, such as flame for flammability, skull and crossbones for acute toxicity, or corrosion for damaging substances.

A large diamond-shaped warning sign affixed to transport vehicles, rail cars, or containers that identifies the hazard class and, where required, the specific material being carried.

The transport document that accompanies a hazardous materials shipment and records the proper shipping name, hazard class, UN number, packing group, quantity, and emergency response information.

A reference organized by guide number and UN number that gives first responders initial isolation distances, protective actions, and firefighting guidance for hazardous materials incidents.

A substance that causes visible destruction of, or irreversible alteration to, living tissue at a contact site, or that severely corrodes steel or aluminum, typically defined by pH or corrosion rate thresholds.

A liquid with a flash point at or below a defined threshold, meaning it can release ignitable vapors at ordinary handling temperatures and presents fire and vapor explosion hazards.

The lowest temperature at which a liquid releases enough vapor to form an ignitable mixture with air near its surface, used to classify flammability and set storage and handling controls.

The minimum temperature at which a material spontaneously ignites in air without an external ignition source, informing hot-work limits, equipment selection, and fire prevention planning.

The minimum concentration of vapor in air below which a flame will not propagate, making atmospheres below this level too lean to burn but still potentially hazardous to health.

The maximum vapor concentration in air above which a flame will not propagate because the mixture is too rich, relevant to tank entry, purging, and confined space decisions.

A substance that yields oxygen or otherwise promotes combustion of other materials, increasing fire intensity and creating incompatibility hazards when stored near fuels or organic matter.

A substance that can vigorously polymerize, decompose, condense, or react with water, air, heat, or shock, releasing energy, toxic gas, or fire under handling conditions.

A substance that reacts with water to release heat, flammable gas, or toxic vapor, requiring dry storage, exclusion from sprinkler areas, and specialized firefighting tactics.

The condition in which two or more materials react dangerously when mixed or stored together, producing fire, explosion, heat, or toxic gas; drives segregation and separation requirements.

The physical separation of incompatible hazardous materials by distance, barrier, cabinet, or separate room to prevent dangerous reactions if containers leak, break, or are mishandled.

A barrier, dike, berm, or liner that captures leaks and spills from primary containers, sized to hold the largest container volume plus precipitation or firewater allowance.

A regulatory or advisory airborne concentration, averaged over a stated time, that is considered acceptable for worker exposure across a shift or short-term period.

The legally enforceable airborne concentration limit set by a workplace safety authority that employers must not exceed for exposed workers over a defined averaging period.

An exposure metric that averages airborne concentration over a standard work period, typically eight hours, to compare measured worker exposure against an occupational limit.

Clothing and equipment such as gloves, respirators, goggles, and suits worn to shield workers from chemical, physical, or thermal hazards that engineering and administrative controls cannot fully address.

A device that filters, purifies, or supplies breathing air to protect the wearer from airborne contaminants or oxygen-deficient atmospheres, selected by hazard and assigned protection factor.

A breathing apparatus that delivers clean air from a remote source through a hose or cylinder, used where contaminants exceed filter capacity or the atmosphere is oxygen deficient.

A portable breathing unit carrying its own compressed air supply, worn by responders entering immediately dangerous atmospheres or unknown-concentration environments.

An atmospheric concentration that poses an immediate threat of severe health effects, irreversible harm, or escape impairment, requiring the highest level of respiratory protection.

The controlled process of entering a space with limited access and poor ventilation that is not designed for occupancy, requiring atmospheric testing, permits, attendants, and rescue provisions.

A portable instrument that measures the concentration of flammable vapor or gas in air, typically displayed as a percentage of the lower flammable limit.

The perimeter established around a hazardous materials release, sized from initial isolation and protective action distances, to keep unauthorized people out and limit contamination spread.

The organized actions taken to stop a release, contain and absorb material, protect drains and waterways, decontaminate the area, and dispose of recovered waste properly.

The process of removing hazardous material from people, equipment, and surfaces through washing, absorption, or chemical neutralization to prevent secondary exposure and spread.

The principle that a hazardous waste generator remains responsible for the waste from the point of generation through storage, transport, treatment, and final disposal, even after transfer.

The tracking document that accompanies hazardous waste shipments, recording generator, transporter, and receiving facility signatures to document the chain of custody.

Waste classified as hazardous because it exhibits measurable ignitability, corrosivity, reactivity, or toxicity rather than because it appears on a specific regulatory list.

Waste designated as hazardous by regulation because it appears on published lists of specific industrial, commercial, or discarded chemical streams, regardless of its measured characteristics.