Document JXOm4G29JEJK0XEr8GXow4rv

O ^ ^f^ S SILICONES & URETHANE INTERMEDIATES P. 0. BOX 8361, SOUTH CHARLESTON, WEST VIRGINIA 2S303 to (N.m.j DTMi.ioo lotAliOrt Mr. R. E. Crum Mr. C. E. Fry H. W. Himes, M.D. R. W. Holland, M.D. Mr. R. D. Nelson MsY F. M. Plechaty Mr. M, C. Polniaszek Copies: Mr. H. E. Bishop Mr, R. 0. Cavender/R. P. Campbell Mr. E. B. Harris Mr. T. E. Lawrence Mr. L. E. McClure Mr. J. B. Mickey Mr. D. G. Moshier D,,, June 7, 1983 Originating Dap. $flfety & Health sobiect Corporate Policy Draft Medical Surveillance of Respirator Hearers Attached for your review and comments is a draft of a Corporate Category II policy related to determining the capability of employees to wear respiratory protection equipment. Please let me know your comments' or suggestions for changes to this proposed policy/procedure by June 30th. Very truly yours. JSC:ke Ext. 2618 Attachment 2 UCC 006994 INTERNAL CORRESPONDENCE ftC/ITF|| sr JUH g JS83 4' *' Cfllttij UNION CARBIDE CORPORATION old ridgesury foao, oanburv, ct osei7 Td OMam*) O'VAion Location Ar*a Copy to GOHC (General Occupational Health Committee) Divisional Employee Relations Managers General Safety Committee Data Or-iQinatinp Oept. Area Sufciact June 3, 1983 Corporate Medical/HSBEA Danbury, P2594 Category II Policy Medical Surveillance of Respirator Wearers Enclosed Is a draft of a Category II policy on Medical Surveillance of Respirator Wearers. Included with it are minimum criteria for medical evaluation of respirator wearers and guidelines for UCC physicians regarding medical contraindications to respirator usage. You will notice that Berlle Barton, Harry Rhodes and Bob Onducsin were on the committee chaired by T. Guy Fortney which developed this policy. Please review this draft policy within the next 30 days and send your comments to me. If you have any questions about the details of any of these documents, please call us. Thomas A. Lincoln, M.D. Corporate Medical Director TAL:cms enclosure c: With Cover Letter Only B. Ballantyne, M.D. T. G. Fortney, M.D. A. A. Lang, M.D. H. C. Lewinsohn, M.D. M. J. Makowsky, M.D. With Final Draft J. B. Browning R. tf. Cope R. D. Ondocsin A. C. Voress I UCC 006995 pweaai: CORPORATE OCCUPATIONAL MEDICAL MANUAL -SUKTeOT-------------------------------------------------------------------MEDICAL SURVEILLANCE OF RESPIRATOR WEARERS ecti>nT POLICIES/PROCEDURES DATE 4/13/83 1?AG OF mAPPLIES TO UNITED STATES P international! PURPOSE/BACKGROUND The Corporate Occupational Medicine Policy prescribes a coordinating role to the Health, Safety and Environmental Affairs Department with the duty and authority to develop and issue policies, procedures, and objectives for medical examinations, including surveillance examinations. As a part of the program to protect the health of employees potentially exposed to identified toxic materials or biological substances requiring the wearing of respiratory protective devices, the Corporation requires such employees to have a medical evaluation and be certified as able to use the device without risk to the particular employee or others in the work environment concerned. The wearing of respirator protection devices (respirators) may impose some physiological and psychological stress on the wearer. It is, therefore, necessary to perform a medical evaluation of the employee prior to initial use and periodically thereafter. POLICY . 1. All employees who will wear respirators, regardless of the frequency of use, will be required to have medical evaluations prior to fit testing or usage. A register of such employees shall be maintained by Component Management. UCC 006996 CORPORATE OCCUPATIONAL MEDICAL MANUAL "STJS^eCT MEDICAL SURVEILLANCE OF RESPIRATOR WEARERS 5ecti6n POLICIES/PROCEDURES DATE A/13/83 PAGE OF m aAPPLIES TO ` UNITED STATES INTERNATIONAlJ 2. Medical evaluation may be accomplished by the use of the pre-placement examination, the basic periodic medical examination and an re-evaluation as outlined in "Minimum Criteria for Medical Evaluation of Respirator Hearers", developed.,in conjunction with this policy/ - .: . . . , ... ... ' . . .. 3. When an employee is assigned work requiring the wearing of a : respirator, the OCC physician may certify the employee to wear a ^ ; l respirator based on a review of a previous medical evaluation provided it was performed within the preceding twelve months.' - 4. If an employee elects to wear a respirator in a situation^ where it's use is not mandated or considered necessary by the i Component Facility, a medical evaluation is nevertheless required. If the Component Facility makes the respirator available on a voluntary basis,, the Component will become responsible for ensuring the medical evaluation be performed in accordance with the preceding items 1-3 of this policy. 5. The UCC physician rendering the medical opinion after evaluation of a prospective respirator wearer shall be provided the following information by management.* A. Physical requirements of the job. - *APPENDIX I UCC 006997 CORPORATE OCCUPATIONAL MEDICAL MANUAL THS3ICT MEDICAL,SURVEILLANCE OF RESPIRATOR WEARERS SeEti&n POLICIES/PROCEDURES DATE 4/13/83 3[PAGE OF El aAPPLIES TO UNITED STATES international] B. Stresses involved, i.e., asbestos, paints, carcinogens, solvents, etc. C. The type of respirator to be worn. ,f- 6. Employees who have Medical approval to wear contact lenses, regardless of work area, will not be permitted to wear a_~ ' full-face respirator, helmet or hood. ~ % SCOPE This policy applies to all parts of Union Carbide in the United States and Puerto Rico. REFERENCES 1. Corporate Occupational Health Manual, Policy/Procedures for Medical Examinations. 2. Corporate Occupational Health Manual, Policy/Procedures for Respiratory Protection. 3. OSHA General Industry Standards, 29 CFR 1910.134. Advice and Services Corporate Occupational Medical Director Old Ridgebury Road Section P-2 Danbury, Connecticut 06817 - END - UCC 006998 rsugjKT-------------------------;------------------------------------------- SeCtTSn ! -------- GUIDELINES/INFORMATION EVALUATION OF RESPIRATOR WEARERS "TE 4,15/83 F* TTfT APPLIES TO * ' (T) UNITED STATES Q INTERNATIONAL GENERAL The Corporate policy titled Medical Surveillance of Respirator Hearers establishes requirements for the medical evaluation and certification of employees who will wear respirators. These guidelines may be used by components to assist them in developing their detailed medical evaluation procedure. MINIMUM CRITERIA Pre-Placement Examination: The UCC physician who performs the pre-placement examination shall be informed if the prospective employee is required to wear a respirator in the normal course of his/her work. The examining physician shall determine the employee's ability to do so. The results of this determination shall be transmitted to plant management in writing.* 1. The minimum requirements of the pre-placement examinations shall * bes . a. Completion of UCC Form 166-90, revised 2-BO or equivalent. b. Physical examination * c. Chest x-ray (Postero-anterior view 14* x 17*) *APPENDIX I UCC 006999 CORPORATE OCCUPATIONAL MEDICAL MANUAL "-sdeteOT---------------------------- ;------------------------------------------- feE'CTlbN ' , 1 ! --------- GUIDELINES/INFORMATION EVALUATION OF RESPIRATOR WEARERS DATE 4/13/83 |PAGE 2 OF 4 APPLIES TO ' 0 UNITED STATES Q INTERNATIONAL d. Pulmonary function testing, to include Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV^) , FEVj/FVC ratio, a comparison of the determined and predicted values and a graph for permanent retention. e. Electrocardiogram f. Audiogram / g. Visual/Acuity, Depth and Color Perception h. Complete Blood Count i. Urinalysis j. If the employee is to be working in an area where ther^, is potential for exposure to significant chemical of physical stresses, a panel of blood chemistry tests should be added to the pre-employment examination. Basic Periodic Examination: After the initial evaluation of the employee's ability to wear a respirator, there shall be periodic evaluations in accordance with the schedule and requirements for the basic^periodic examination in Corporate Policy: Medical Examinations, to certify the 'employee's suitability to continue use of a respirator.. Pertinent statutory or regulatory requirements for persons exposed to specific hazardous materials or - conditions requiring more frequent examinations will take precedence over h* this scheduling* UCC 007000 UNION CARBIDE, CORPORATE OCCUPATIONAL MEDICAL MANUAL STJETeET MINIMUM CRITERIA FOR MEDICAL EVALUATION OF RESPIRATOR WEARERS 5eCti6n" GUIDELINES/INFORMATION DATE 4/13/83 Tpage OF APPLIES TO ' fTl UNITED STATES international! 1. Scheduling a. Every five years for employees age 35 or younger, , b. Evjwy^iwoxereJ-onet-half years for employees 36-50 years of age. . c. Yearly for employees over 50 years of age. 2. Minimum requirements for the basic periodic examination shall be: a. Interval history using medical form UCC 275-26, 5/82 or equivalent. _ b. Physical examination. c. Pulmonary functiontesting, to include Forced Vital Capacity (FVC), Forced Expiratory Volume ` in one second ^FEV^), FEVj/FVC ratio, a comparison of the determined and predicted values and a graph for permanent retention. A careful and detailed respiratory history is an important part of the pulmonary function evaluation. d. Electrocardiogram every five years for employees over the age of 45. Required for employees with a history of heart disease with each scheduled examination. e. Chest x-ray every five years unless exposed to pulmonary irritants or has symptom^ of lung disease. f. Complete Blood Count. UCC 007001 UNION CARBIDE corporate occupational health manual ' "SUBJECT-------------- :---------------------------------------------------------- secti6n GUIDELINES/INFORMATION MINIMUM CRITERIA FOR MEDICAL " DATE. 4/13/83 (PAGE 4 OF 4 EVALUATION OF RESPIRATOR WEARERS APPLIES TO ' g] UNITED STATES ^ INTERNATIONAL g. Urinalysis. b. Audiometric test every five years unless exposed to noise at or above 85 d&A TWA. _ , 1. Visual acuity* depth and color perception, j. Any other test determined to be necessary,by the physician. AnmnMte^wliiatloir Those years that a basic periodic examination is not performed* there shall be a medical determination of the employees ability to continue wearing a respirator based on any pertinent changes In health status which have occured in the preceding 12 months. A questionnaire may be used to establish the health status of registered respirator wearers. The initial screening in the annual review process may be. conducted by the company nurse* if present, or by the Respirator Program Administrator, with the prior approval of the UCC physician using as a minimum requirement the Respirator Hearers Annual Review Questionnaire.** The questionnaire may be expanded by the UCC physician. If there is a positive response to any of the questions on the questionnaire, the employee -must be referred to the UCC physician for further examination. The UCC physician may examine the employee or perform those tests that he feels ace necessary to make this annual medical determination of the employee's ability to continue wearing the respirator safely. If there are no positive responses; the employee may continue the use of a respirator for another 12 months. appendix ii . - BHD " UCC 007002 CORPORATE OCCUPATIONAL HEALTH MANUAL SUW.eC* GUIDELINES FOR UCC PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR USAGE . 3ecti6n" DATE GUIDELINES/INFORMATION IPAGE j APPLIES TO 0 UNITED STATES El international] GENERAL It is the responsibility of the UCC physician to determine the health status of all job applicants and employees wbo may be required to wear respiratory protection equipment in the performance of their duties. As i there is little published information available on the adverse physiological effects of wearing a respirator, it is difficult for s physician to precisely identify medical contraindications to respirator usage. The only practical approach is to treat each case individually, using the best medical judgement available, and to consider the physical characteristics and disadvantages of the various types of respirators.* Appendix III lists the general types of respirators and some of the stress factors that may be anticipated with their usage. Air purifying respirators resist inhalation because the filter or cartridge restricts free air flow. Exhalation is also more difficult because the expired air must force open a valve for release. The bulk and weight of some self-contained breathing apparatus (sCBA's) are a significant burden and could aggravate inguinal hernia or place additional stress on .the cardiovascular system. Hearers of airline respirators and hoods may have to drag around several hundred feet of air supply hose. If the worker's APPENDIX III UCC 007003 CORPORATE OCCUPATIONAL MEDICAL MANUAL ---------------------------- ;------------------------------------------- Section GUIDELINES/INFORMATION : MEDICAL CONTRAINDICATIONS TO RESPIRATOR USAGE DATE 4/13/83 |PAGE 2 0F 7 APPLIES TO ` fx? UNITED STATES Q INTERNATIONAL / cardiovascular or pulmonary system is impaired, wearing a respirator could constitute an unacceptable risk. Based on the overall health of the Individual, special medical testa and the physical examination, the physician shall determine whether an employee may wear a respirator safely or whether an employee should be restricted from wearing respiratory protection equipment. If a restriction is recommended, appropriate management must be notified in writing using the form given in Appendix I. GUIDELINES Pulmonary Disease Considerations . If an individual has emphysema, chronic obstructive pulmonary disease, restrictive pulmonary disease, bronchial asthma or x-ray evidence of pneumoconiosis, a physician should determine whether or not a respirator can safely be worn. - Performance on pulmonary function testing will be a major factor in this determination. A moderate to severe ventilatory abnormality is technically defined ast 1. FEV^ less than 60% of predicted. 2. FVC less than 60% of predicted. - 3. PEVj/FVC ration less than 60% of predicted. ' UCC 007004 CORPORATE OCCUPATIONAL MEDICAL MANUAL smm---------------------------- ;-------------------------------- GUIDELINES FOR UCC" PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR USAGE Section'" GUIDELINES/INFORMATION DATE A/13/83 1P*GE 3 ' 1~ 0F~ 7 APPLIES TO ^' " El UNITED STATES international! These readings could result in an employee being under excessive stress while wearing a respirator and result in injury. The individual with this abnormality needs to have close observation and questioning. A careful and detailed pulmonary history may reveal that he/she is able to climb steps and walk up a grade without difficulty and could safely perform tasks wearing a respirator. There may be x-ray evidence of pneumoconiosis but no functional impairment is demonstrated. The asthmatic who has difficulty only at the time of an upper respiratory infection or seasonally may be able to function normally except at a time of an acute attack. Some arrangements, which must be accomplished in writing, could be made with supervision for his/her utilization. Cardiovascular; Cardiovascular impairment should always be treated with more concern than pulmonary impairment because of its potential sudden catastrophic consequence. Applicant or employees who have the following conditions must be evaluated very closely. For this group it is wise to seek consultation with the individOiTl^''Tamlly*physieian*-or ''cardiologist and let this physician be a part of the decision making process. UCC 007005 CORPORATE OCCUPATIONAL HEALTH MANUAL SUBJECT------------------------------------------------------------ GUIDELINES FOR UCC PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR USAGE Secti6n-- . 1 l________________quidelines/inforhation ' DATE ! [PAGE oFl APPLIES TO * E3 UNITED STATES international) 1. Class 2 (or worse) organic heart conditions as defined .In the American Medical Association's Guidelines to the Evaluation of Permanent Impairment. 2. Uncontrolled hypertension. 3. History of a previous heart attack. 4. Coronary by-pass surgery. Other Conditions Other medical conditions are generally less important in terms of ability to wear a respirator but should be considered. 1. Epilepsy may be a contraindication to wearing a respirator as hyperventilation could precipitate a seizure. 2. Insulin dependent diabetics prone to hypoglycemic episodes may need to be excluded from wearing a respirator as the additional work involved in wearing a respirator could precipitate a hypoglycemic episode and place the individual and others at risk. 3. Claustrophobia requires special consideration. Some employees may use this to keep from weering a respirator or to be relieved from jobs requiring the use of a respirator. It is, therefore, essential that the physician make a determination of the validity of the employee's phobic complaint. UCC 007006 CORPORATE OCCUPATIONAL MEDICAL MANUAL "SSIEJeC? . GUIDELINES FOR UCC' PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR USAGE SECTION 1 GUIDELINES/INFORMATION DATE 4/13/83 (PAGE 5 OF 7 APPLIES TO ' El UNITED STATES a international! Questions which may be useful include the following: Has the individual ever worn a respirator before? What types of response occured? How long was the individual able to wear the respirator without experiencing symptoms of fear? The real danger of a phobic individual is that he or she could rip off a respirator in a toxic environment. The examining physician may wish to have a. psychiatric evaluation of the individual's complaint. 4. A perforated eardrum is reported to have the potential of permitting toxic gases to be Inhaled when using a negative pressure respirator. It is important to question the employee/applicant with a perforated eardum about whether they can blow air through their eustachian tube. 5. Facial hair lying between the sealing surface of the respirator and the wearer's skin will always prevent a good seal. Company policy does not allow respirator wearers to have facial hair at the point -of sealing. Black employees'may have a condition known as Pseudofolliculitis barbae which prevents them from shaving daily, therby causing a serious problem in wearing' a respirator. The U.S. Navy has found that sealing requirements UCC 007007 CORPORATE OCCUPATIONAL MEDICAL MANUAL --susjeCI ;--------------------------------- GUIDELINES FOR UCC PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR -USAGE SECTION " !' GUIDELINES/INFORMATION DATE 4/13/83 |PAGE 6 & 7 mAPPLIES TO m ----- UNITED STATES Q INTERNATIONAL can be net by shaving every second to third day using 000 barber clippers. The employee or applicant with this condition should be offered this alternative before placing a permanent: restriction of respirator usage. . 6. Some individuals develop a sensitivity to the rubber of the respirator mask. This can usually be overcome by changing to a respirator with a. synthetic facepiece. 7. An individual with a complete loss of the sense of smell would have difficulty with a qualitative fit test, the ability to recognize canister breakthrough or may be unable to ceqognize odors requiring immediate respirator usage. 8. Certain devices require dexterity in the connection and disconnection of parts and for the manipulation of valves and fittings during use. Persons with missing or disabled fingers may have difficulty in using these devices, particularly in an emergency when help may not be aveilable. It may be necessary to allow the individual in question to wear the required respirator under close medical supervision and monitor his/her ability to perform the required job duties. UCC 007008 mrec?------------- ----------------------------------- GUIDELINES FOR UCC PHYSICIANS REGARDING MEDICAL CONTRAINDICATIONS TO RESPIRATOR -USAGE SeCtISn ~ GUIDELINES/INFORMATtOK DATE 4/13/83 (PAGE j 1: OT 7 ` mAPPLIES TO ' UNITED STATES INTERNATIONAL /. The medical determination of physical ability to wear a respirator safely will be left to the IrtdlvidualTiDCCyphysiclan' afte't^^xaminixSrand queatioht^-^ppricant/eWpTciyei. /;This information, coupled with the type. `X-. ' of respirator to be worn, type of work to be performed, and the contaminant to be encountered, will enter into the physician's opinion that will then be related to Management for final action.. END #2643B UCC 007009 CONFIDENTIAL APPENDIX I AUTHORIZATION FOR EXAMINATION DATE Examinee's Name Employee's No.S.S.Job Title Type of Examination: ( ) Pre-Employment ( ) Basic Periodic ( ) Special Examination (specify) ( ) Other (specify) Physical Requirements of Job (i.e. heavy lifting, sustained physical effort, light work,....) Typ* of Hazards Involved (i.e. noise, asbestos)_______________________ Respirator to be Horn Type None Types of Tests to be Performed: 1) Medical Exam UC 136-90 2) Medical Re-exam recordForm UC 275-26 5/82 3) Physical Exam by Doctor 4) Pulmonary Function 5) Chest x-ray 6) EKG 7) Audiogram Co8m)plete Blood Count He9m) oglobin U1r0in) alysis V1is1u) al Acuity, Color Depth Perception . Bl1o2o)d Chemistry O1th3e) r (specify)________________ UCC Authorizer Address HEALTH STATUS REPORT The following medical recommendation is based on a review of the medical history, laboratory test results, physical exam and type of physical requirements of the position applied for or occupied by the individual named below. Applicant/Employee is medically qualified to wear a respirator: | |ycs J (no ( ) Class A Medically qualified ( } Class B Medically qualified - Minor controllable defects present (i.e. eyeglasses) RECOMMEND` ( ) Class C Medically qualified for modified work only, in accordance with the following RESTRICTIONS ( ) Class D Medically unqualified for job title and job requirements as listed above ( ) Class Temporarily medically unqualified (i.e. hernia or other correctable problem) SIGNATURES Employee and/or applicant has been informed of all abnormalities' discovered as a result of this examination. DATE EXAMINER DATE EMPLOYEE/APPLICANT Physician to complete and return to authorizer at above address. Retain Medical Forms. UCC 007010 APPENDIX It RESPIRATOR WEARERS ANNUAL REVIEW QUESTIONNAIRE To be answered by employee DATE LOCATION DATE EMPLOYEE NUMBER NAME (last) ' (first) DEPARTMENT RESPIRATOR TYPE Dust Mask QHalf Mask Full Face SCBA Airline Other:[ YES NO In the past year have you had a prolonged absence due to Injury, Illness or major surgery................................................................................................ ............... ........ Are you troubled by shortness of breath when hurrying on level ground or walking up a slight hill?................................................................... ............... ........ Do you have asthma?.............................................................................................................................. ........ Do you have heart or blood vessel disease? Do you have fits, spells or seizures? Do you have chronic lung problems? Are you bothered with claustrophobia? Do you have difficulty with taste or smell? ................................................ (Only If SCBA will be worn) - Do you have any physical problems which would limit your ability to wear a 35 lb. air pack? . . . . Since your last health evaluation, have you been told you have diabetes ............................. punctured eardrums. epilepsy(fits,seizures) anemia ........ Do you know of any reason why you are not able to wear a respirator?_____ _____ t understand the questions above and have answered to the best of my knowledge. I understand that I have the right to request an examination by a physician. SIGNATURE OF EMPLOYEE DATE UCC 007011 APPEND I X IN TYPES OF RESPIRATORS There are two major classifications of respirators: l) air purifying and 2) air supplying. Further subclass!flcat Ions are shown below. Both physiological and psychological stress may be Imposed on an Individual by respiratory protection equipment. 1. AIR PURIFYING RESPIRATORS Air purifying respirators reduce the level of breathing zone air contaminants by means of chemical or mechanical filters. Pressure Inside the facepiece will be negative during inhalation and positive during exhalation for all non-powered air purifying respirators. This will Increase the resistance of Inhalation and exhalation and, therefore. Increase the work of breathing. A. Particulate Filter Respirators Particulate filter respirators provide protection against airborne particulate matter Including dust, mists and metal fumes by physlctally trapping the particles In a fibrous material as the air passes through the filter media. A negative pressure is created Inside the facepiece during inhalation. Breathing res 1 stance wl11 Increase as the dust load on the filter increases. (Figure 1) Particulate filter respirators are available as disposable and non disposable. (Figure 2) In general, the disposable dust mask (Figure 1) Imposes less resistance to breathing than the cannlster type respirators. !S FIGURE A B DISPOSABLE RESPIRATORS Dust Mask Particulate or Chemical UCC 007012 FIGURE 2 HALF MASK FULL FACE NON-DISPOSABLE RESPIRATORS PARTICULATE OR CHEMICAL B. Chemical Cartridge RespIrators , Chemical cartridge respirators provide protection against certain acid gases and organic vapors. Chemical sorbent cartridges or canalsters absorb or otherwise trap the gaseous and vapor contaminants as the Inhaled air passes through them. A negative pressure Is created inside the facepiece during inhalation. Breathing resistance will remain relatively stable for the full service life of the cartridge or cannister. Disposable and non-dIsposab1e varieties Impose roughly equivalent breathing resistance. See Figure IB and Figure 2. C. Powered Air Purifying Respirators Powered air purifying respirators will provide protection against particulates and/or organic vapors depending upon the particular model. Air is forced through a filter or chemical cartridge by a battery operated blower and then supplied to the respirator facepiece under positive pressure. There will be minimal breath ing resistance associated with this type of respirator. FIGURE 3 UCC 007013 II. AIR SUPPLYING RESPIRATORS Air supplying respirators provide the wearer with a Supply of breathing air from a cylinder or compressor and protect against gases, vapors and particulates. Certain types can be used In oxygen deficient atmospheres. Two broad categories of this type of respirator are airline respirators (Figure 4) and self contained breathing apparatus (SCBA) (Figure 5). In the former the respirator Is connected by a hose (300 ft. is maximum length) to remote compressed air cylinders or an air compressor. A self contained breathing apparatus is a portable cylinder of compressed air carried by the respirator wearer which may weigh -as much as 35 pounds. The length of airline to be handled and the weight of SCBA's are physical stresses to be considered In approving an Individual to wear this equipment. Further physiological stress Is imposed on the wearer by the design of the air delivery system as defined below. AIRLINE RESPIRATORS A. Demand Airflow AIr1IneNrestSirators and SCBA's may be equipped with demand airflow respiratora7 This type of regulator supplies breathing air to the respirator "on demand", I.e., when the wearer Inhales. Negative pressurels created in the facepiece during inhalation and positive pressure- during exhalation. Breathing resistance is minimal with a demand regulator. B. Pressure-Demand Airflow Alternatively, airline respirators and SCBA's may be equipped with pressure-demand airflow regulators. In addition to supply ing breathing air to the respirator when the wearer Inhales, ' a small flow of air Is continuously supplied to the respirator to maintain a positive pressure within the facepiece. This UCC 007014 B. Pressure-Demand Airflow Cont'd prevents Inward leakage of contaminated air during Inhalation. A pressure-demand airline respirator or SCBA has a springloaded exhalation valve which requires a more forceful exhal ation to open. This Increased breathing resistance Is a consideration In approving an Individual to wear respirators equipped with pressure-demand regulators. C. Continuous Airflow Airline respirators only, not SCBA's, may be equipped with continuous flow valves which supply a predetermined flow of breathing air to the respirator at all times. Breathing resistance Is minimal with continuous flow systems. UCC 007015