Airborne contaminants vapors

B. The vapor pressure of a substance determines its potential maximum air concentration and influences the degree of inhalation exposure or airborne contamination. Vapor pressures fluctuate greatly with temperature. 

R.E. Cuthrell, Description and operation of two instruments for continuously detecting airborne contaminant vapors, in K.L. Mittal (Ed.), Surface Contamination, vols. 1-2, Plenum Press, 1979, p. 831. 

Among the major potential hazards affecting working environment are chemical (airborne contaminants), biological, and physical hazards,. ir contaminants are commonly classified as either particulate contaminants or gas and vapor contaminants. Common particulate contaminants include dusts, fumes, mists, aerosols, and fibers. 

Air-purifying respirator A respirator that removes airborne contaminants, such as particulates, gases, vapors and fumes, from ambient air through filtration, absorption, adsorption, or chemical reactions on the media contained in the cartridge or filter. 

Because SPMDs have high sampling rates (Rs s) for vapor phase contaminants, all SPMDs are assembled in an environmentally controlled room equipped with an activated carbon air filtration system for the removal of airborne contaminants. SPMDs of almost any length can be prepared after allowance of space for the molecular welds or heat seals (i.e., 2.5 cm for each end). However, different... 

This technology is applicable to the treatment of industrial wastewater and contaminated groundwater. The same technology can also be used to effectively destroy airborne contaminants in the off-gases from industrial processes, air strippers, or soil vapor extraction operations. 

Within the plants surveyed, styrene was the principal airborne contaminant of concern. Since these surveys were made in operating plants, there were other substances present however, styrene was the dominant vapor and the only one potentially of concern relative to accepted exposure limits (TLV s). 

Ambient blanks are intended to detect airborne contamination that may be affecting samples collected in atmospheres with high contents of organic vapor. This type of ambient contamination may be present at airport runways, refineries, gasoline... 

Exact Solution for Mixtures of N Components With Addictive Effects and Different Vapor Pressures, Threshold Limit Values of Airborne Contaminants and Physical Agents, pp. 43-45, ACGIH, Cincinnati, Ohio, 1971. 

Substances with high vapor pressures tend to volatilize more quickly and can reach higher maximum air concentrations than substances with low vapor pressures. Some substances have such low vapor pressures that airborne contamination is a threat only if they are finely dispersed in a dust or mist. 

Local exhaust refers to any method designed to capture airborne contaminants nearest the point of generation or release. The system should draw the contaminant away from a person s breathing zone. Mechanical exhaust dilutes contaminated air and lowers the concentration of a hazardous substance. The effectiveness depends on the number of air changes per hour. A fume hood or fume removal system can capture hazardous air contaminants such as vapors, dusts, mists. 

There are two main forms of airborne contaminants. There are particulates and gases or vapors. 

Check operations for generation of heat, gases, vapors, or airborne contaminants. Place them in locations to minimize the portions of the building affected. Capture cmtaminants at the source to minimize the volume of air requiring treatment. Consider the effects of spills and leaks and how to manage them. 

In addition, depending on the type of chemicals and type of exposure, the respiratory tract should also be protected against inhalation of airborne contaminants, which can be in the form of particles, vapors or gases. Also, hearing protectors should not be forgotten. The need to use hearing protectors starts when the noise level, in spite of engineering control measures, exceeds the national limit value, which is 90 or 85 dB in many countries (Korhonen 1997). 

The atmospheres in a confined space may be immediately dangerous to life or health (IDLH) because of toxic air contaminants or lack of oxygen. Before any company employee enters a confined space, tests must be performed to determine the presence and concentration of any flammable vapor or gas or any toxic airborne particulate, vapor, or gas and to determine the oxygen concentration (follow all procedures as outlined in the company s Confined Space Program). 

Airborne contaminants can be present as liquids or solids, as gaseous material in the form of a true gas or vapor, or in combinations of both gaseous and particulate matter. Most often, airborne contaminants are classified according to physical state and physiological effect on the human body. Knowledge of these classifications is necessary for proper evaluation of the work environment. One must also consider the route of entry and action of the contaminant. 

NIOSH has developed Guidance on Emergency Responder Personal Protective Equipment for Response to CBRN Terrorism Incidents where the NFPA 1994 Standard sets the performance requirements for protective ensembles used in response to CBRN terrorism incidents. The standard defines three classes of ensembles (Classes 2, 3, and 4) based on the protection required for different hazard types (vapors, liquids, and particulates) and airborne contaminant levels. 

Biofiltration works to degrade a diversity of airborne contaminants, including industrial chemicals like styrene (Arnold et al. 1997), pentane and isobutane mixtures (Barton et al. 1997), toluene (Matteau and Ramsay 1997), chlorinated benzenes (Oh and Bartha 1994), dimethylsulfide (Pol et al. 1994), ethylene (Elsgaard 1998), and other volatile organic compounds (VOCs Leson and Winer 1991). Maintenance of good degrada-tive activity of biofilter microbial communities sometimes requires the addition of nutrients to the bioliltration matrix, since materials like peat or wood chips are generally nutrient poor. Adjustments and careful control of environmental variables such as temperature, pH, and availability of moisture (humidity) also are often required (Arnold et al. 1997 Matteau and Ramsay 1997). Removal rates for contaminants by biofilters can be impressive. For example, removal of vapors of chlorinated compounds (chlorinated benzenes, in one instance) was measured at 300 g of solvent vapor h m of filter volume (Oh and Bartha 1994). 

Inhalation involves those airborne contaminants that can be inhaled directly into the lungs and can be physically classified as gases, vapors, and particulate matter that includes dusts, fumes, smokes, and mists. Inhalation, as a route of entry, is particularly important because of the rapidity with which a toxic material can be absorbed in the lungs, pass into the bloodstream, and reach the brain. Inhalation is the major route of entry for many hazardous chemicals in the work environment. 

MIST Produced by hot VAPORS that cool and condense at room temperature, an airborne contaminant. 

---