Types of Respirators

Earlier in the chapter we said that respirators could be categorized into three types the SCBA, the SAR, and the air-purifying respirator. Each serves the same function, to give the user safe breathing air and to prevent hazardous chemicals from being inhaled and going directly into the bloodstream. 

Supplied-air respirators (airline respirators) supply air to a facepiece via a supply line (hose) from a stationary source. SARs are available in positive-pressure and negative-pressure modes. Pressure-demand SARs with escape provisions provide the highest level of protection and are the only SARs recommended for use at hazardous waste sites. SARs are not recommended for entry into IDLH atmospheres unless the apparatus is equipped with an escape SCBA. The air source for supplied-air respirators may be compressed air cylinders or a compressor that purifies and delivers ambient air to the facepiece. All SAR couplings must be incompatible with the outlets of other gas systems used on site to prevent a worker from connecting to the wrong gas source (nitrogen, hydrogen, etc.). 

SARs enable longer work periods than SCBAs and are less bulky. However, the airline impairs worker mobility and requires workers to retrace their steps when leaving an area. Also, the airline is vulnerable to puncture fiom rough or sharp surfaces, chemical permeation, and obstruction from falling material. For this reason SARs users carry a five minute escape bottle of compressed breathing air with them. Should the air hose become punctured they 

Most chemical sorbent canisters and cartridges have an expiration date and may be used up to that date as long as they have not been opened previously. Once opened, they absorb humidity and air contaminants even if they are not in use. Cartridges should be discarded after use and should not be used for longer than one shift or when breakthrough occurs, whichever comes first. 

High relative humidity which may reduce the protection offered by the sorbent. 

Employers must conduct workplace evaluations to ensure the scope of the written respirator plan protects those required to use respirators. Employers must also evaluate the continued effectiveness of the written respirator plan. Proper evaluations help to determine if workers use and wear respirators correctly. The evaluations can also indicate the effectiveness of respirator training. Employers must solicit employee views about respirator plan effectiveness and determine any problem areas. 

OSHA requires employers retain written information regarding medical evaluations, fit testing, and respirator plan effectiveness. Maintaining this information promotes greater employee involvement and provides compliance documentation. Employers must retain a record for each employee subject to medical evaluation. This record includes results of the medical questionnaire and, if applicable, a copy of the healthcare professional s written opinion. Maintain records related to recommendations, including the results of relevant examinations and tests. Retain the records of medical evaluations and make them available as required by 29 CFR 1910.1020, Access to Employee Exposure and Medical Records. Retain fit test records for users until the administration of the next test. 

Persons assigned tasks requiring the use of a respirator must possess the physical ability to work while using the device. OSHA requires employers to ensure the medical fitness of individuals that must wear respirators. The fitness evaluation considers the physical and psychological stress imposed by the respirator. It must also evaluate the stress originating from job performance. Employers must ensure that employees pass the evaluation prior to fit testing or permitting the use of the respirator for the first time. A physician or other licensed healthcare professional must 

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No matter what type of respirator is used, it is of the utmost importance that the revised respiratory standard is adhered to. The revised standard stresses training, documentation, written programs, medical surveillance, fit testing, and a variety of other subjects pertinent to respirators. Of particular interest to the authors is the new approach toward action levels, protection factors, and fit testing. Another important change is OSHAs latest approach on voluntary respirator use. With the new standard in effect, those workers previously considered to be voluntarily wearing respirators should be much better protected. 

In rabbits under light amytal anesthesia, chlordan has no direcr effect on the blood pressure, but produces a type of respiration having many characteristics in common with Cheyne-Stokes type. The generalized tremors, opisthotonus, tonic and clonic convulsions, produced by chlordan were decreased or abolished and respiration restored to normal by suitable injections of the sodium salts of amytal, phenobarbital, and pentothal. The LD60 of chlordan, which was about 20 mg. per kg. on intravenous administration to intact rabbits, was increased to about 60 mg. per kg. through the antidotal action of the barbiturates. An unidentified chlorine-containing degradation product with acidic properties was recovered from the urine of rabbits treated with chlordan. Approximately one third of its chlorine content was set free on hydrolysis at 100° C. with sodium hydroxide in either absolute alcohol or in water. 

The antagonistic effects of sodium pentothal on the blood pressure and the respiratory effects of chlordan are illustrated in Figure 1, C. The intermittent severe tremors with concomitant Cheyne-Stokes type of respiration produced by the injection of chlordan were decreased or entirely abolished, and both the respiratory rate and depth were restored to near normal. A dose of barbiturate sufficient to diminish the tremors appreciably and to restore the respiration to normal also produced a temporary drop of 10 to. 40 mm. of mercury in blood pressure. 

Respirators always compromise worker ability. A worker with a respirator is unable to perform or respond as well as a worker without one. Various types of respirators are listed in Table 3-11. 

These type of respirators reduce the user s exposure by a factor of 50 if the user has been properly fit tested. 

Protection Factor (PF) The ratio of contaminant concentration outside of the respirator facepiece to that inside. It is taken as an indication of fit. PF values are established by manufacturers for specific types of respirators and are indicators only. Actual protection will depend on how a specific respirator fits a specific individual. Refer also to Fit Factor. 

Respiration is a broad term for the oxidation of organic materials to carbon dioxide. When the electron acceptor is not oxygen they are called anaerobic respirations. Table S.I4 illustrates possible types of respiration. Nitrate, sulphate and carbon dioxide are significant electron acceptors in anaerobic respiration and many are of environmental significance. 

Q5 Restrictive lung disease reduces lung capacity and results in rapid, shallow breathing. This type of respiration tends to wash C02 out of the lung and may result in an increase in blood pH. Gas exchange in alveoli is reduced or inadequate because of the poor expansion of lung tissue, so the arterial P02 of arterial blood may also be rather low. 

In the event of deployment of chemical weapons, emergency care providers will be at serious risk of exposure, and special respirators may be needed for additional protection. There are several types of respirators, each providing a different level of protection. 

Some pesticide labeling lists the type of respirator yon shonld wear when handling the product. Other labeling requires the use of a respirator, but does not specify the type or model to be used. NIOSH (National Institnte of Safety and Health) and MSHA (Mine Safety and Health Administration) approve respirators as adequate for certain types of nses. When the pesticide labeling le-qnires you to use a respirator, wear one that is approved by NIOSH and MSHA. If the respirator has more than one part, all the parts mnst be approved. 

Air-supplying respirators are used in a few specialized situations where other types of respirators are not protective enough. Use an air-supplying respirator when the pesticide labeling tells you to do so. In addition, you should use one when handling pesticides ... 

This type of respirator supplies clean air from cylinders that you carry, usually on your back. This lets you move more freely and over a wider area than you can with a supplied-air respirator. Get training from competent instructors before using any type of respiratory protection, especially self-contained breathing equipment. These devices contain a limited air supply (usually about 30 minutes), which may be used up even more quickly in high temperatures or with excessive exertion. Figure 6.13 shows the different air-supplying respirators, the airline and self-contained breathing apparatus. 

Type of respirer Electron acceptor Product Distribution of ability s... 

Assess cardiac and respiratory status including rate, depth, rhythm, type of respirations, and quality and rate of pulse. Assess lung sounds for rhonchi, wheezing, and rales. 

Before Assess and monitor rate, depth, rhythm, and type of respiration,... 

Intranasal 0.03% two sprays two to three times/day 0.06% two sprays three to four times/day Assess and monitor rate, depth, rhythm, and type of respiration. 

Respirators provide protection against inhaling harmful materials. Different types of respirators may be used depending on the level of protection desired. For example, supplied-air respirators (e.g., a self-contained breathing apparatus) may be required in situations where the presence of highly toxic substances is known or suspected and/or in confined spaces where it is likely that toxic vapors may accumulate. On the other hand, a full-face or half-face air-purifying respirator may be used in situations where measured air concentrations of identified substances will be reduced by the respirator below the substance s threshold limit value (TLV) and the concentration is within the service limit of the respirator (i.e., that provided by the canister). 

Types of respirators, use, storage, maintenance, and step-by-step fitting instructions. 

Asbestos characteristics and hazards, precautions for removal, protective clothing, and types of respirators. 

Calcium Oxide Protective gloves, goggles and any type of respirator prescribed for fine dust. Flush with water and seek medical help. Flush with water and seek medical help. 

Sulfate respiration is probably only a distant relative of the other types of respiration and photosynthesis. The sequence Clostridium-De-suljotomaculum Desuljovibrio represents a probable line of evolutionary development marked by increasing elaboration of cytochrome-using electron transport chains. 

TABLE 15. Guide for Selection of Respirators Type of respirator... 

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