Oxygen deficiency, explosive gases, flammable gases, and toxic gases and condensation occur in confined spaces. Otherwise, innocuous conditions are exacerbated when they occur in a confined space.
(A) Oxygen deficiency. Air normally contains 21% oxygen. Air containing less than 19.5% oxygen is dangerous and air containing 16% or less oxygen can be lethal. In a confined space, oxygen-deficient atmospheres are produced by two factors:
(1) The consumption, without replacement, of oxygen by some means such as a reaction of oxygen with container walls as in rusting, or by flames and internal combustion engines; and
(2) The displacement of oxygen by another gas such as methane, hydrogen sulfide, or carbon dioxide.
(B) Accumulation of toxic or combustible gas. A number of gases commonly encountered in confined spaces include:
(1) Carbon monoxide, a toxic and sometimes explosive gas which is colorless, odorless, and nonirritating. It is produced by internal combustion engines as well as various other processes;
(2) Hydrogen sulfide has the distinctive odor of rotten eggs and is extremely dangerous. Hydrogen sulfide gas very quickly paralyzes the sense of smell so odor alone does not always give an adequate warning. A concentration as low as 0.5% will cause immediate death. It is poisonous and explosive. It is found in many sewage system confined spaces; and
(3) Methane (natural gas) is a product of decaying organic material and has no odor, color, or taste. It can be dangerous because it can displace oxygen and it is explosive.
(1978 Code, § 8.28.020) (Ord. 92-2, passed - -1992)