Airborne contaminants particulates

Foulants enter a cooling system with makeup water, airborne contamination, process leaks, and corrosion. Most potential foulants enter with makeup water as particulate matter, such as clay, sdt, and iron oxides. Insoluble aluminum and iron hydroxides enter a system from makeup water pretreatment operations. Some well waters contain high levels of soluble ferrous iron that is later oxidized to ferric iron by dissolved oxygen in the recirculating cooling water. Because it is insoluble, the ferric iron precipitates. The steel corrosion process is also a source of ferrous iron and, consequendy, contributes to fouling. 

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. 

As previously indicated, most bag-type filters require a pre-coat of particulates before they can effectively remove airborne contaminates. However, particles can completely block air flow if the filter material becomes overloaded. Therefore, the primary operating criterion is to maintain the efficiency of the filter media by controlling the cleaning frequency. 

Areas for the manufacture of sterile products are classified according to the required characteristics of the environment. Each manufacturing operation requires an appropriate level of microbial and particulate cleanliness four grades (Table 22.1) are specified in the Rules and Guidance for Pharmaceutical Manufacturers and Distributors (1997), defined by measures of airborne contamination (Table 22.2). Environmental quality is substantially influenced by the air supplied to the manufacturing environment. 

The greatest risk of contamination of a pharmaceutical product comes from its immediate environment. Additional protection from particulate and microbial contamination is therefore essential in both the filling area of the clean room and in the aseptic unit. This can be provided by a protective work station supplied with a unidirectional flow of filtered sterile air. Such a facility is known as a laminar airflow unit in which the displacement of air is either horizontal (i.e. from back to front) or vertical (i.e. from top to bottom) with a minimum homogenous airflow rate of 0.45 ms" at the working position. Thus, airborne contamination is not added to the work space and any generated by manipulations within that area is swept away by the laminar air currents. 

May be useful only when sampling water for low-level YOC or other airborne contaminant analysis is conducted in an area with high level of YOC emissions or airborne particulate matter. Due to a short exposure time to atmospheric air during sampling, these contaminants are usually undetectable in ambient blanks. 

Airborne contaminants existing in a laboratory have a variety of sources, but they are generally a mixture of particles generated within the laboratory itself and those already present in the air that is drawn into the room. The contaminants are normally in gaseous or particulate form, but liquids in form of aerosol can also occur. 

Other than isotopes separation for uranium enrichment described in Chapter 2, inorganic membranes are commercially used for particulate filtration of air or other gases in clean room applications, airborne contaminant analysis and high-purity hydrogen production. In addition, some inorganic membranes are us in pH and ion selective electrodes. 

Two types of sampling monitors are in general use air samples are used to assess the airborne contamination levels at selected points. In the case of particulate materials a volume of air is drawn through a filter paper on which the particulates are deposited. An alarm may be set on increase of activity. 

Clothing worn in the clean area must be of non-shedding fibres terylene is a suitable fabric. Airborne contamination, both microbial and particulate, is reduced when trouser suits, close-... 

Under the broad terminology of atmospheric contamination, both microbiological and particulate airborne contamination can be considered. These two aspects should partly be considered together, especially as microbial contamination will frequently increase or reduce according to the cleanliness of both the product and the pack, i.e. particulates can be a bioburden carrier. 

Ordinary chemical laboratories may be used for radiochemical work at low levels of short lived 0-y radionuclides (e.g. half-lives < 14 d and activity levels < 10 kBq). However, it is recommended that a special room be used for radioactive woric. In the design of such a laboratory it is important that airborne contamination be prevented from spreading to counting rooms and to offices. Therefore, a pressure difference between the laboratories and the other areas is desirable. The air velocity in the fume hoods should never be below 0.25 m s , and 0.5 m s is recommended. With such a flow velocity, radioactive dust and fumes are retained in the hood and removed through the vents. The fume hoods should have filters for collecting radioactive particulates. 

Bakand S, Winder C, Khalil C et al (2006) An experimental in vitro model fm dynamic direct exposure of human cells to airborne contaminants. Toxicol Lett 165 1-10 Bartoli CR, Wellenius GA, Diaz EA et al (2009) Mechanisms of inhaled fine particulate air pollution-induced arterial blood pressure changes. Environ Health Perspect 117 361-366 Becker S, Soukup JM, Sioutas C et al (2003) Response of human alveolar macrophages to ultrafine, fine, and coarse urban air pollution particles. Exp Lung Res 29 29-44 Beckett WS, Chalupa DF, Pauly-Brown A et al (2005) Comparing inhaled ultrafine versus fine zinc oxide particles in healthy adults a human inhalation study. Am J Respir Crit Care Med 171 1129-1135... 

Additionally, to limit the buildup of contamination in the above designated areas, airflow is established to continually remove airborne contaminants. Airflows in the system are established at prescribed flowrates such that they are adequately filtered prior to being discharged to the environment. All air drawn from Zone 1 is exhausted through charcoal and HEPA filters to remove halogens and particulate contaminants from the exhaust air prior to release to the atmosphere. These ventilation filter systems are equipped with test ports and are periodically checked for operating efficiency. In addition to the ventilation system filters, in-box filtere are used to reduce the levels of airborne contaminants that are drawn into the Zone 1 ducting. 

The nature of respiratory hazards in the workplace is twofold, containing either gaseous or particulate airborne contaminants. There are three types of gaseous contaminants with which a worker may come in contact, including ... 

An employer must first identify the nature of the airborne contaminant using the following criteria Is the contaminant a particulate or a gas Is it a chemical or a biological agent And finally, are there any mandatory occupational exposure levels for the contaminant Only when the nature of the contaminant is determined can the employer begin crafting the appropriate safety protocol in handling the situation. 

Diesel exhaust is a dangerous airborne contaminant. Currently available control technology could significantly limit many diesel exhaust exposures, although additional information and research is needed on the methods to monitor diesel particulates, and determine the level of risk such particulates cause. OSHA is developing an action plan to reduce worker exposures to this hazard but is not initiating rulemaking at this time. 

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

Particulates Particulates include dusts, fumes, smoke, aerosols, and mists. Particulates also have classifications by size and chemical makeup. Shape can also be important. For example, some particulates have long, thin, fibrous shapes. Others may be spherical and have a fairly imiform cross-section. Figure 25-5 (Chapter 25) provides size characteristics of some airborne contaminants. 

Clean rooms are rooms used for manufacturing or research work that requires workspaces that have very low levels of dust, airborne microbes, particulates, or vapors. A ventilation system continually provides clean air to the room. The ventilation system operates upstream of the room. Workers may wear protective clothing to prevent any clothing fibers or hair from contaminating the space. They enter and exit through airlocks to prevent contaminants from entering the room. 

Probably the least understood piece of safety equipment is the respirator. Although dust masks may protect workers against many airborne particulates, these offer little or no protection against volatile chemicals. Respirators should be considered for use only by trained and certified employees, only under special circumstances, and only after all other controls of airborne contaminants have been implemented. In the laboratory, exhaust fans and fume hoods represent the first line of defense to contain and/or exhaust volatile hazardous materials. Without appropriate training, certification, medical approval, and careful fitting to the user s face, the use of respirators may, by itself, pose a significant health hazard. 

At various times, the EDB also received radioactive wastes from the N Reactor lift station. Since the N Reactor was shut down In 1987, water has been maintained In the EDB [approximately 2,800,000 L (750,000 gal)] so that the bottom sludge layer will not become exposed. Subsequent drying of the sludge could expose receptors to airborne exposure from contaminated particulate matter. Filtered river water has been added as needed to maintain the water level. Documentation of the amount of water added to the EDB has not been maintained. There are no documented releases associated with the unit (DOE-RL 1990). 

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. 

In selecting these air monitors, the physical form (i.e. in gaseous or particulate form) in which airborne contamination is present as well as the chemical forms of certain radionuclides (e.g. radioactive iodine) should be taken into account. Measurements of air contamination should be conducted in a way that makes the samphng as representative as practicable. 

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. 

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