ACID A chemical compound whose aqueous solution turns blue litmus paper red, reacts with and dissolves certain metals to form salts, and reacts with bases to produce salts and water. They are capable of transferring a hydrogen ion (proton) in solution.

ACUTE Describes a severe and often dangerous condition in which relatively rapid changes occur.

ACUTE TOXICITY Adverse health effects occurring within a short time period of exposure to a single dose of a chemical or as a result of multiple exposures over a short time period, e.g. 24 hours.

AEROSOL A colloidal suspension of liquid or solid particles dispersed in gas.

AFFF, AQUEOUS FILM-FORMING FOAM Fire-fighting foam which flows on burning liquid as a film, providing rapid knock-down.

ALCOHOL-RESISTANT FOAM Foam for use against fires involving liquids miscible with water, e.g. alcohol, acetone.

ANION A negatively charged atom or group of atoms, or a radical which moves to the positive pole (anode) during electrolysis.

ANOXIA Deficient supply of oxygen to tissues.

ANTIBODY A modified protein circulating in the serum of an animal, synthesized in response to a foreign molecule (antigen) that has entered the body.

ANTIGEN A foreign substance (usually a protein) that stimulates formation of antibody.

ASPHYXIA The result of a diminished supply of oxygen to the blood and tissues and interference with the respiratory function. Simple anoxia may be caused by 'inert gases', e.g. nitrogen, and some flammable gases, e.g. methane. Toxic anoxia may be caused by certain substances, e.g. carbon monoxide and hydrogen cyanide, which interfere...