INDUSTRIAL HYGIENE GASES, VAPORS, AND
SOLVENTS
UNIVERSITY OF HOUSTON – DOWNTOWN
FALL 2013
GAS/VAPOR
For IH purposes, a substance is a GAS if
this is normal physical state at room
temperature (25 degrees C) and oneatmosphere pressure.
Examples: CO, Cl, Oxygen, and Nitrogen.
If substance is normally a liquid at normal
temperature and pressure, then the gaseous
component in equilibrium with liquid state is
a VAPOR.
Examples: CCl4, HCOH, and Benzene.
MORE TERMS
Vapor Pressure – measure of the
concentration of the chemical in the air at
equilibrium.
Solvents are liquids in which a solute can be
dissolved.
-Volatility
-Polarity (“like dissolves like”)
-Solubility
ROUTES OF EXPOSURE
 Dermal absorption
 Inhalation of vapors
 Aerosolized mist of the solution can cause
exposure to solutes
EXPOSURE FACTORS
 Temperature and Volatility
 Concentration
 Reactivity (air, moisture, acids and bases)
ORGANIC COMPOUNDS
 Organic Solvents (Table 7-A)
-Hydrocarbons contain carbon and hydrogen
atoms
-Halogenated hydrocarbons – chlorine,
fluoride, iodine and/or bromine
HAZARDS OF GASES, LIQUIDS,
SOLVENTS and VAPORS
 Compressed gas – pressure build up
 Cryogenic Liquids – frostbite, oxygen
deficiency
 Flammability
 Explosions
 Reactivity
HAZARDS OF GASES, LIQUIDS,
SOLVENTS, AND VAPORS
 Flash point - is when a liquid is the lowest temp at which it
gives off enough vapor to form an ignitable mixture with the
air near the surface of the liquid or in a vessel capable of
flame propagation away from the source of ignition
 Flammable liquid - CC flashpoint below 100 F and vapor
pressure not exceeding 40 psi absolute at 100 F (Class I
liquid)
 Combustible Liquid - CC flashpoint at or greater than 100
F (Class II – III liquids)
HAZARDS OF GASES, LIQUIDS,
SOLVENTS, AND VAPORS
 Lower and Upper Flammable Limit- mixture of vapor with
air that, if ignited, just propagate flame. (% by volume of
vapor in air)
 Flammable Range (Explosive Range) – includes all the
concentrations of a vapor in air between the lower
explosive limit (LEL) or lower flammable limit (LFL) and the
upper explosive limit (UEL) or upper flammable limit (UFL).
HEALTH EFFECTS
IRRITANTS
Solubility vs. Activity Considerations.
Upper Respiratory Tract
Examples: Ammonia, Acrolein, Formaldehyde,
Sulfur Oxides.
Lower Respiratory Tract
Examples: Nitrogen Dioxide, Phosgene, Ozone.
Both Upper and Lower Irritants
Examples: Chlorine, Ozone.
ANESTHETICS
Central Nervous System (CNS)
depressants; cause narcosis.
Examples: Most Aliphatic Hydrocarbons or
Organic Solvents; Alcohols, Esters, Aldehydes,
Ketones.
HEMOLYTIC AGENTS
Cause damage to the blood or hematopoietic
system.
Examples: Aniline, Arsine, Benzene, Nitrobenzene.
ASPHYXIANTS
Ability to deprive tissue of oxygen.
Two Types:
– Simple – physiologically inert gases which
act by accumulating in sufficient quantity to
exclude adequate oxygen supply.
Examples: CO2, methane, ethane, He, H, N.
– Chemical – act through direct chemical
action to render the body incapable of
utilizing oxygen.
Examples: CO, HCN, and H2S.
HEPATOTOXIC AGENTS
Adversely affect liver function.
Examples: Carbon Tetrachloride, Chloroform,
Nitrosamines, Tetrachloroethane.
NEPHROTOXIC AGENTS
Adversely affect kidney function.
Examples: Most Halogenated
Hydrocarbons, Uranium, Mercury, Lead,
Cadmium.
NEUROTOXIC AGENTS
Interfere with proper function or cause
damage to the nervous system.
Examples:
CNS - Organometallic Compounds,
Methyl Mercury, Tetraethyl Lead.
Peripheral - Arsenic, TOCP.
SENSITIZERS
Agents that cause recurrent effects after
the worker becomes sensitized (allergic)
to the toxin. First few exposures may
cause no reaction, but then reactions can
occur from later contact with small
quantities for very short periods of time.
CARCINOGENS
Stimulate or speed the development of
cancer.
Examples: BCME, Vinyl Chloride,
Benzidine, Chromium.
EVALUATION OF HAZARDS






Toxicity of the substance
Concentration in the breathing zone
Manner of use
Length of time of the exposure
Control in place
Employee susceptibilities
CONTROL OF HAZARDS
 Substitution (i.e. benzene for toluene,
xylene)
 Engineering controls
 PPE (respirator, gloves, eye wear)