It is determined by the vapour pressure of the liquid, since only when a sufficiently high vapour concentration is reached, can it support combustion. It should be noted that the source of ignition need not be an open flame, but could equally be, for example, the surface of a hot plate, or a steam pipe. H Hazard Codes - see UN hazard codes. A Hematopoietic Agent is a chemical which interfers with the blood system by decreasing the oxygen-carrying ability of haemoglobin. This can lead to cyanosis and unconsiousness.
Carbon monoxide is one such agent, familiar to smokers.
A Hepatotoxin is a chemical capable of causing liver damage. The H ealth and S afety E xecutive. The HSE is responsible for proposing and enforcing safety regulations throughout UK industry and academia. Publications are available on a wide variety of safety-related issues. Hypoxia is a condition defined by a low supply of oxygen.