Expressed as % of gas in air by volume. It is the critical concentration below which the ignition will not occur. Above this concentration, any spark will ignite the explosive mixture.

Expressed as % of gas in air by volume. It is the concentration beyond which workers who are exposed to this gas may suffer adverse effects of toxic poisoning.

It is the time-weighted average concentration of a substance over a 15 min period thought not to be injurious to health

Time-weighted average (TWA) is a method of calculating a worker's daily exposure to hazardous substances such as fumes, chemicals, gases, or vapours. It is averaged to an 8-hour workday, along with the average levels of exposure to the hazardous substance and the time spent in that area.

BAC - Blood Alcohol Content refers to the percent of alcohol (ethyl alcohol or ethanol) in a person's blood stream.