# CRITERIA DOCUMENT: RECOMMENDATIONS FOR A STANDARD FOR EMERGENCY EGRESS FROM ELEVATED WORKSTATIONS

# I. RECOMMENDATIONS FOR A STANDARD FOR EMERGENCY EGRESS FROM ELEVATED WORKSTATIONS
The National Institute for Occupational Safety and Health (NIOSH) recommends procedures and equipment for worker emergency egress from elevated workstations as set forth in the following sections. The standard is designed to assure workers of the availability of a means of emergency egress during situations in which there could be a threat to life, health, or safety.
Compliance with the standard should therefore prevent bodily injury or death resulting from:
(1) unavailability or insufficient capacity of egress facilities;
(2) unfamiliarity with emergency procedures and egress facilities;
(3) inadequate identification and illumination of egress facilities;
(4) lack of awareness of an imminent danger or present emergency; and (5) physical or medical conditions which adversely affect the worker's ability to make effective use of egress facilities.
Sufficient equipment and knowledge of its proper use exist to permit compliance with the recommended standard.

# (c)
Unit of Exit Width: Each 22-inch wide segment of a standard means of exit. For purposes of this standard, fixed, portable, or job-made ladders of standard construction shall constitute one unit of exit width.
Requirements for standard means of egress are expressed in units of exit width and are determined according to occupancy load. (E) Fixed ladders meeting the requirements of 29 CFR 191029 CFR .27 or 1926.

# (F)
Portable ladders meeting the requirements of 29 CFR 1910CFR .25, 1910CFR .26, or 1926.
(G) Job-made ladders meeting the requirements of 29 CFR 1910CFR .25 or 1926.
(2) Special means of egress: Situations where there is not a reasonable probability that danger to life, health, or safety may suddenly develop.
(2) High Hazard Situation:
Situations where there is a reasonable probability that danger to life, health, or safety may suddenly develop.
(c) General Requirements (1) Every workstation or open structure 15 feet or more above the permanent or temporary floor or ground level, in a low hazard situation that is designed for an occupancy load of 10 employees or more, shall be provided with at least two means of egress.
(Examples of such workstations include maintenance platforms and elevated storage tanks.)
(2) Every elevated workstation above the permanent or temporary floor or ground level, in a high hazard workplace where egress may be impeded by obstructions, shall be provided with at least two means of egress without regard to the minimum number of employees occupying the workstation.
(3) Egress facilities must be available and useable at all times in buildings under construction. Such egress facilities shall consist of doorways, walkways, and items listed in Section 2 -Means of Egress. The capacity of the combined means of egress shall be sufficient .4
for the occupancy load, but in no instance shall there be less than 2 means of egress remote from one another.
The capacity of a unit of exit width shall be as follows:
(A) Standard egress facilities (as listed in Section 2 -Means of Egress, paragraph b, items 1, A-G).
(i) Stairways-One unit for each 60 persons.
(ii) Ramps-One unit for each 60 persons.
(iii) Horizontal exits-One unit for each 100 persons.
(iv) Ladders (standard fixed, job-made, or portable)-One unit for each 15 persons (Note-A standard fixed, job-made, or portable ladder conforming to applicable standards will be considered as one unit of exit width.) (B) Special egress facilities (as listed in Section 2 -Means of Egress, paragraph b, items 2, A-D). Special devices shall be installed by the employer only after evaluation of the workplace egress needs, with due consideration to the capacity limitations of such devices.
(5) Emergency egress facilities shall be positioned as far from each other as practicable provided that they are so arranged that travel of more than 100 feet from any point to the nearest means of emergency egress will not be necessary, except in high hazard situations where travel distances shall not exceed 75 feet.
On every workstation of such size, arrangement, or occupancy that a fire or other emergency may not in itself provide adequate warning to the workers who may be occupying the workstation, emergency alarm facilities shall be provided as necessary to warn workers of the existence of fire or other emergency so that they may escape, or to facilitate the orderly conduct of egress drills.
Where employees are required to work alone and away from direct contact with supervisory personnel or other employees, a reliable means of warning shall be provided, eg, two-way radios, telephones, "intercoms," or alarms. (e) These examinations shall be reviewed yearly and repeated at a frequency determined by the responsible physician in order to provide the worker with current evidence of physical ability to perform the job safely and meet the requirements of egress.

# (f)
The employer shall ensure that pertinent medical records are maintained and are available for review during the term of employment.
These records shall be available to the medical representatives of the Secretary of Health, Education, and Welfare, of the Secretary of Labor, of the employee, and of the employer. Instructions for evacuation procedures established by the employer shall be posted in places readily accessible to employees, in each work area subject to this standard.
(c) Instructions shall be printed in English. They shall also be printed in the predominant language of non-English-speaking workers, if any, unless these workers are otherwise informed. All illiterate workers also shall be so informed.
(d) Each path of escape from the work area to a place of safety shall be so arranged or marked that the route is unmistakable. Arrows pointing to exit routes or "Exit" signs may be used for this purpose.
(e) The minimum level of illumination along the entire path of egress shall be not less than 5 foot-candles (preferably 10-15 footcandles) with provision to maintain this level in the event of power failure.
Occupational Safety and Health Administration.
(2) American National Standards Institute.
(3) National Fire Protection Association.
(4) Federal Aviation Administration.
(5) California Safety Orders.
Japan Fire Regulations.
Additionally, a literature search was conducted in order to review the technology pertaining to human escape from elevated areas, including those involving industrial areas and buildings under construction.

# III. EFFECTS OF EXPOSURE

# Extent of Exposure
An emergency egress situation is one in which the usual means of egress, for one or more workers, has been blocked or eliminated, and there is a need for prompt escape, because of a work accident, fire or explosion, power shutdown or other disaster. As will be developed later in this document, egress is normally a problem at elevations of over 15 feet.
From data taken from the 1970 census of the United States, it is estimated that approximately 2.4 million workers could be working, on an occasional or regular basis, at a height of over 15 feet or more above the grade or floor level.
The census data are summarized in Table VII.  While the number of individuals who work at elevated workstations is important in determining the extent of exposure, it is also important to determine the frequency of occurrence of high egress emergency situations.
Statistical data to identify such occurrences are not reliable because many high egress emergency situations have been described as "falls" or "burns."
For example, a crane operator burned in his cab due to lack of egress has a "burn" injury, while one who jumps has a "fall."  Newspaper articles often relate events concerned with workers falling from heights ; however, they fail to give details covering the emergency situation which the workmen faced.

# Historical Reports
In 1783 Sebastian Lenormand made a descent from the top of an observatory in France. Using an umbrella-like device, he landed safely and regarded the apparatus as a new means of escaping from fires in tall buildings.  De Haven  in 1942 reported eight cases where adult men and women survived after jumping or falling from heights of between 55 and 146 feet. Although this report examined bodily injuries due to falls, ie, the mechanical and physical laws interacting between the human body and the impact medium, its importance relates primarily to efforts to reduce injury resulting from impact and not to providing alternate means of egress from an elevated workstation.
Since World War II, US Army parachute training injuries at Fort Benning, Georgia, have been closely followed.  The injury rate has been consistently below 1%. However, the data are of little applicability, because practice jumps from heights offering any potential for significant injury are made with harness-suspension and descent devices. Thus, the use of these built-in safety measures are not representative of the type of emergency situation faced by workers where an alternate means of egress from an elevated workstation is required.

# Effects on Humans
Very little research, if any, has been conducted in the area of the psychological stress on humans during the need for emergency egress from high workstations, according to a written communication from M Wilson, American Psychological Association, December 1973.
A "threat-to-life" psychological stress test situation was described, however, in the final report of a research project conducted for the National Aeronautics and Space Administration by the Martin Marietta
Corporation.  The results of the tests indicate that persons under stress could experience a loss of operational efficiency of up to 34 %.
Additional statistics cited in the report show that under emergency situations, 10 times as many men as normal may be required to operate equipment with which the men are familiar. Analysis of these data indicated that psychological stress during emergencies may lower operating efficiency within a group by as much as 90%.
This report concluded that, as a result of the breakdown of reasoning and decision-making processes during emergencies, the following items should be made an essential part of egress systems:
(1) A minimum of decision-making should be required on the part of the user.
The egress procedure should be as simple as possible.
The egress procedure sequence should be as close as possible to commonly used procedures.
Three recommendations in the report  also are of prime interest in the development of egress systems.
The system should be reliable, safe, and fast.
The system should be simple to operate.
The personnel who will use the system should have extensive training in its use.
There is also a lack of published data documenting the physical effects on the human body of jumping or falling from high machinery or structures in industry.
(Written communications from A Harrison, National Technical Information Service, US Department of Commerce, and from IJ Bhambri, Smithsonian Science Information Exchange Inc, 1973)
Swearingen et al  tested the maximum gravitational force (Gforce) the human body could tolerate while in various positions when subjected to vertical impact. A total of 500 test drops were made with 13 volunteers in a specially constructed drop mechanism. G-force tolerance was determined by progressively increasing the impact loadings to the point where subjects complained of severe pain.
Some of the test drops were conducted with the volunteers in a standing position with knees bent slightly, allowing the trunk, head, and arms to sustain less severe impacts. This is the position that would be assumed in reaching grade level after jumping from height during an emergency. However, because the construction of the test mechanism limited the height from which test drops could be made, it was impossible to determine maximum G-force impact tolerances with the body in this position.
Because the study concerned only G-force tolerance, it failed to include sufficient data to extrapolate the heights from which the drops were made. Moreover, those tests which did establish maximum G-force tolerances were conducted with the body seated in a rigid chair, seated in a chair containing shock-absorbing material, standing with knees locked, or squatting with knees fully flexed. These positions could not realistically be expected in case of voluntary jumping from heights.
Of significance, however, is the fact that this study demonstrates a feasible method of determining the heights from which a person could jump without injury.
Injury data from the states of California,  Florida,  New
York,  and Pennsylvania,  although reflecting reliable recordkeeping, are inadequately classified to allow identifying the number of injuries from emergency egress. For example, California includes in "falls or slips from elevation,"  falls by workers from loading docks, slightly elevated platforms, vehicles, down steps, etc.
Florida includes in its accident data "falls to a different level" covering 1967 through 1972.
 Included are scaffold falls, falls from walkways and platforms, falls into excavations, shafts, floor openings, and falls from roofs and wall openings. There is no information relating these injuries to the lack of emergency egress facilities.
As with California and Florida, data from New York and Pennsylvania reflect the same concerns-accidental falls, presumably including, but not limited to, egress situations in high structures and machinery.  Insurance industry statistics have not been made available for this review.
However, it is understood that these data include incomplete information with respect to emergency egress facilities. For example, falls from elevations include falling in holes, off platforms, through wall openings, etc, without further identification of causes.

# IV. PRESENT EQUIPMENT, STANDARDS, PROCEDURES, AND TRAINING EVALUATION Present Equipment
Standard exit and egress facilities include fixed, portable, and job-made ladders, stairways, ramps, and horizontal exits. One of the descent methods makes use of a device which applies friction to the descent line.  Attached to the unit is a belt, sling, or "chair" into which the person is firmly buckled. These devices are compact and lightweight-one unit including the descent line is intended to be kept with the worker.
In case of an emergency, he first secures the descent line, attaches the unit to the descent line, snaps his suspension attachment into the device, and steps off the structure. By applying hand or finger pressure to the device, additional friction can be transmitted to the line to slow or stop the descent.
Such devices can, in case the worker employs a lifeline, be attached to the lifeline and serve to lower him if he should fall or his equipment should fail.
With another type of controlled descent device,  the descent line from which the person is suspended drives a system of gears. This gear mechanism imparts a braking action to the line, thereby controlling the rate of descent. The gear unit is attached to a fixed point overhead.
In case of an emergency, the worker buckles into a chest sling which is attached to one end of the rope, throws the remaining portion of rope (the "loose" end) to the ground, and steps off the structure.
With this type of controlled descent devices, as one person is descending, another chest sling at the opposite end of the rope is raised.
This can provide means of escape for other persons; however, only one person at a time can descend.
One of these units is preset by the manufacturer to lower a person at a rate of about 3 ft/sec.
 The mechanism of this type of device Examination of this statement leads to the conclusion that requirements in the code relating to worker egress are lacking in specific definitions, making it necessary to employ a significant degree of judgment when attempting to apply these requirements.
The ANSI standard concerning steel erection, A10.13, paragraph 10. 1.5,  requires that at least one stairway be installed to within four floors or 60 feet, whichever is less, of the uppermost working floor.
A tubular steel scaffold with stairs is acceptable as a stairway. This requirement attempts to provide a means of emergency egress; however, it is inadequate for two important reasons: 1) only one stairway is required;
should it be blocked in an emergency, no alternate means of egress would exist, and 2) the requirement for installation of the stairway to within four floors or 60 feet of the uppermost level does not provide any requirement for means of egress from the top working floors.
Although ladders or personnel hoists are the normal means of access to the top working floors, no requirements are included in the standard to specify minimum numbers of ladders based on employee population at levels above those requiring permanent stairways.
Requirement for maximum travel distances between ladders also is not set. Another corporation has installed controlled descent devices in some of its facilities. (J Ellis, oral communication, October 1973) This was a decision made at one of the corporation's facilities after an appraisal of the potential hazard.
In other locations, the corporate representatives considered the problem of no consequence and elected not to make any provisions for emergency egress.
Another corporation  acknowledged that crane safety devices can be considered component parts of the cranes.
In any case they should be maintained in good condition and replaced or repaired at once if failures occur.
A British steel firm  provides "some means of emergency escape from the (crane) cab," in addition to the stairways and walkways which normally provide a means of access.
A US petroleum company,  in a series of booklets pointing out process hazards and suggesting ways to correct them, requires escape routes from certain high areas. The company specifically requires at least two exits from all buildings and enclosures (except small storage or equipment areas that are rarely entered by personnel). In addition, stairways and ladders should be located on the outside of structures, and stairways requiring escape traffic to pass through a process equipment structure to get from the end of one stair to the beginning of another must be avoided. In a typical case, in spite of a tenminute warning of an impending ditching of a DC-9 aircraft, the purser misunderstood the urgency of the situation. Several passengers and stewardesses were still standing, and at least five other passengers did not have their seatbelts fastened at impact. After the ditching, not one of the five 25-man life rafts had been successfully deployed. Twenty-two of the 63 people on board ultimately died when the aircraft sank fifteen minutes after impact.  In a study of 43 cases where evacuation was required following accidents to tricycle-landing-gear transport aircraft, it was found that descent devices were used in only seven of the fourteen cases where it was available and should have been used.  Another important behavior pattern which occurs in such situations is inaction. However, Johnson  in a paper presented in 1969 indicated that his search of the literature led him to the conclusion that no experimental study had been performed aimed primarily at determining what precedes or causes inaction, under what conditions it occurs, who is likely to manifest it, or how it can be controlled.
These facts point out that, in spite of the availability of physical means of egress, these are frequently not used to their full potential, as a consequence of which there have been needless injuries and deaths. One way to improve the likelihood of appropriate action is through proper human factors design of egress methods.
In the development of egress procedures, human behavior patterns should be considered so that the procedures are as easy to follow or operate as possible. Where this is not possible, the only way to provide any assurance that emergency egress paths and equipment will be used effectively is through training. These can be summarized as follows:
(1) Perception of the emergency situation.
(2) Recall of information relative to appropriate action.
(3) Choice of the correct action.
(4) Performance of the chosen action.
The presence of an emergency situation means that the worker will be operating under some degree of psychological or physical stress.
( In the aircraft ditching reported earlier,  in spite of the pilot's warning to fasten seatbelts, over 10% of the passengers did not do so.
Hoffler et al  have reported the results of an experiment in which subjects were instructed to don an oxygen mask upon decompression of the room.
In spite of a loud warning tone (which they were informed would precede decompression), the noise of escaping air, and condensation in the room, 4% of the subjects never indicated appropriate recognition of the emergency condition.
Davis   (2) Recall of information relative to appropriate action
The second element involves recall of information relative to appropriate action. Although lack of recall may take place with the passage of time unless practice (ie, reinforcement) intervenes, it is difficult to predict the rate and amount of loss of retention of a given task. These rates of loss of retention are always specific to the task.
The one principle more important than any other is that the amount of retention depends on the level of proficiency achieved during initial learning.  At one extreme, studies have shown that the reading of instruction sheets is very ineffective.
Berkun  had young men in basic training read an instruction manual on ditching before they were taken up in an airplane. An emergency situation was then simulated and subjects were asked to recall the instructions on ditching procedures. An average of only 4.9 out of 12 answers were correctly recalled under these stressful conditions. A nonstressed control group recalled 7.6 out of 12 correctly. This was after an interval of less than one hour following the reading of instructions.
Johnson and Altman  conducted an experiment to find out the value of instruction cards on airline passenger behavior during a simulated evacuation.
Sixty percent of the subjects who were given no instruction card jumped onto the escape slide while 40% sat down on the slide. Use of instruction cards which emphasized jumping raised the percentage to 73.5%.
All the subjects read the cards instructing them to jump. Nevertheless, many failed to jump. Therefore, they either did not understand the instructions, forgot within a few minutes, or consciously elected not to comply with the instructions.
Simple demonstrations have also proved to be ineffective on occasion. Johnson  demonstrated the donning of a lifejacket before a group of subjects and then evaluated their performance of the same action.
Although 38% of those in a control group which did not witness the demonstration were able to don the jacket correctly, only 52% of the instructed subjects were able to do it correctly. However, the demonstration did result in a 45% timesaving for those who were able to do it correctly. The fact that only 38% and 52% in the two groups were able to correctly don the jacket is particularly discouraging since the jackets used were designed to conform to Technical Standard Order C 72-A which stated in Section 4.1.1 that the device "...must be simple and obvious thereby making its purpose and actual use immediately evident to the user."
It also stated in Section 2.1 that where something is "...not obvious to the user, clearly worded instructions must be provided."  There were instructions on the jackets used. These findings are supported by evidence from actual ditchings.  Another study reported that the typical demonstrations of emergency oxygen equipment given on commercial aircraft were frequently ineffective.
As many as 15% failed to put on the mask and over 50% did it incorrectly in an experimental situation.
 The conclusion from these studies supports the concept that demonstrations and instructions need reinforcement, eg, by drills or practice to be effective even in relatively simple procedures.
Well-learned instructions generally will be retained for longer requirements is the choice of the correct action or the decision making process. In emergency egress situations this process is usually limited to deciding whether the emergency requires escape, and, if so, by what means of egress. Although these seem to be rather simple decisions under normal conditions, under the stress of an emergency they may often be wrong.
Improper decisions are made for a number of reasons.
Stress may cause a person to perceive things differently than they are in reality.
Preoccupation may result in a misinterpretation of the seriousness or urgency of the situation.
Or, normal emergency reactions may distort logical reasoning. Thus, the correct decision involved in securing a seatbelt in the face of an impending ditching seems rather obvious, and yet in one study  several passengers were standing and others did not fasten their seatbelts in the DC-9 aircraft ditching reported previously.
Reports from survivors indicated that some people did not believe the emergency was real.
In a series of studies of psychological stress in man, Berkun et al  reported that subjects who had been led to believe that they were in danger from an artillery attack (explosions were set off around their post)
were told that they would be rescued if they could repair their radio and indicate their position. In spite of these instructions, 10 out of 24 chose to abandon their post and escape on their own. Five of these subjects reported, incorrectly, that they had been told to leave. In another case where the danger was due to fire, 2 of 13 escaped; when the hazard was radiation, 3 of 26 left after a period of time. These decisions were based on the subjects' evaluations of the seriousness of the situation and on their judgment of the type of action most appropriate at that time.
These results indicate that people might make inappropriate decisions especially where instruction has been inadequate. For example, when a man is being instructed that he should use a particular door, he should also be told which doors cannot be used and why, eg, fire doors which close automatically. Likewise, the nature and seriousness of possible hazards must be explained to increase the likelihood of proper emergency action. For example, the urgency of escape from radiation exposure is not obvious to the senses, thus workers looking around for a fire or for another obvious sign may decide that the alarm is false.
Berkun et al  reported that approximately half of the subjects interviewed minimized the seriousness of the situation.
All their experiments were conducted with "green" soldiers in their first four weeks of basic training. Troops with more experience (6 months to 6 years) performed more rationally under all conditions. In most cases, it is difficult to determine whether the level of mental skill, motor skill, or perceptual-motor skill is a limiting factor in performance.
Since learning is oriented to specific tasks, it is difficult to generalize on the relative efficiency of the acquisition of skills at these different levels. However, it is generally held that motor and perceptual-motor skills are retained much longer than mental skills.  Therefore, in tasks involving a significant amount of procedural behavior as well as perceptual-motor behavior, the retention of procedural skill is probably the limiting factor.
 Wherever possible, therefore, procedural aspects should be minimized.
Motor skills, such as riding a bicycle, are generally considered to be well retained.  The method of measuring retention in most cases has been to determine the time saved in relearning a task. This criterion is important in terms of determining the quantity and frequency of retraining required to maintain a desired level of skill. However, a high level of motor skill does not help if the action being taken is an erroneous response to the emergency.
Experimental studies  have indicated a fairly substantial decrease in performance with time elapsed since training. However, this decrease in performance is overcome within the first few minutes or by trials of practice. Under emergency conditions, however, there is usually no second chance, so the initial response must be adequate.
In an emergency, the worker will not have a chance to practice his skills on the descent device before using it.
Further, there may be no one around to correct an erroneous decision of a worker whose first impulse has led him to the wrong exit. Fleishman and Parker  reported "the retention of proficiency in a complex, continuous control, perceptual-motor skill is extremely high, even for no-practice intervals up to 24 mo." However, an examination of subjects' initial responses indicate decreases of 50% for a 9-month interval and 67% for 24 months. Ammons et al  reported retention of initial performance levels of 75% after 1 month, 50% after 6 months, and 31% after 1 year. None of these studies involved retention under stress.
Training in the fire service is quite similar to maintenance of emergency egress behavior in that the safety and success of the operation depend critically on speed and require maximum performance. Skills are used at infrequent intervals, but when needed, actions must be performed at a high level of proficiency often under situations of extreme stress. In spite of the critical nature of this training, there is only one known controlled study  concerning required training intervals.
In that study, firefighters were trained on a novel task closely related to their normal duties. This experiment showed that skill deteriorated significantly within 1-4 months from lack of practice. After 1 month, the time required to complete the task increased by 50%, after 2 months by 84%, after 3 months by 91%, and after 4 months by 100%. Performance ratings decreased by 31% within 1 month.
This study  indicates that performance on emergency egress procedures involving perceptual-motor skills, such as operating emergency descent devices or even using ladders, can deteriorate to unacceptable levels within a few months.
(A) Performance under stress Emergency egress by its very nature means there will be some degree of psychological stress involved. Aside from the fact that stress, such as life-threatening situations, may result in inappropriate behavior, there is ample evidence  that it also causes decrease in performance. But where speed of movement is the only action required, such as in a "turn and flee" reaction, the stress may increase arousal and motivation levels resulting in a better performance.
In most other situations, stress will be detrimental. Berkun  found a 10% decrement in cognitive verbal behavior and a 33% drop in performance on a radio repairing task when subjects thought they were exposed to some form of physical danger.
Another group who thought they had injured someone demonstrated an 18% decrement in performance.
It is significant that both experienced subjects and better performers were less affected by stress. The most important factor in improving retention and reducing effects of stress is the initial level of learning.  Overlearning, ie, practice after success has been achieved, results in longer and better retention especially on procedural skills. Goldstein
 has pointed out that overlearning involves learning to such an extent that decision making becomes unnecessary. This increases the likelihood that appropriate task performance of emergency procedures will occur under stressful conditions. Consequently, the time required to relearn is substantially reduced.
(e)

# Scope of Training
The scope and extent of initial training should be based on the type of hazard and the method of egress. The type of hazard will dictate:
(1) Whether speed is essential.
The likelihood that workers may sustain injury before or during egress.
The likelihood that alternative means of egress may be necessary.
(4) Whether protective clothing will be worn.
If external factors such as darkness, heat, chemicals, smoke, etc, will impede egress.
The consequences of mistakes.
The method of egress will determine:
(1) Whether workers are protected from hazards during egress.
The possibility of failure or malfunction of the egress route or device.
The speed of egress.
(4) Whether injury or disablement will affect the use of the means of egress.  In summary, worker egress from elevated workstations has been subordinated in importance by the standards-producing and standardsadopting agencies.
The need for definitive standards on the subject has not been demonstrated by the amassing and analysis of relevant statistics.
Specific language relating to the subject has, in some cases, been dropped
during the standards-adopting process because of the technical nature of the requirements, their economic impact, or their potential for generating negative reaction on the part of factions within the labor/management arena.
When the subject has been included in consensus standards, it has been treated as an adjunct to the general concern of the standard, ie, to ensure that the worker is adequately protected against mechanical hazards.

# Basis for Recommended Standard
The recommended standard is intended to provide all workers whose workstation requires their presence on an occasional, periodic, or daily basis, at a height of 15 feet or more above grade level, with a means of egress that considers three of the following hazard elements included in the Life Safety Code of the National Fire Protection Association  section 2-1, paragraph 2-113:
(1) Height of the workstation.
(2) Hazards associated with the occupancy of the work process.
(3) Number of persons exposed.
This recommended standard applies to all elevated workstations 15 feet or more above grade level except in high hazard situations. Lacking any definitive statistics or results of studies, professional judgment any definitive statistics or results of studies, professional judgment indicates that 15 feet above grade level be established as the lower limit for the standard proposed.
In one instance,  this height was included in a safety standard concerned with worker occupancy of elevated workstations.
A study conducted for the city of Chicago  included the concept of recognizing the different evacuation and rescue procedures associated with emergencies in buildings having occupancies at varying heights. This concept is valuable in recognizing the egress needs of persons working at different levels and ensuring that the additional needs will be met.
Therefore, in the proposed standard, additional requirements are recommended for workstations above 80 feet in height. These are recommended because conventional firefighting ladder equipment cannot reach above 80 feet to provide a means of egress.
 Furthermore, with high machinery and structures in industry, it is reasonable to assume that fewer means of egress are available as the height of the workstation increases.
Requirements for meeting more stringent medical qualifications have been included in the standard for those who work at heights of 80 feet or more above grade level, because they must rely more heavily on their physical, mental, and sensory attributes when using a means of egress from an elevated workstation under emergency conditions.
In their Life Safety Code,  section 4-2, paragraph 4-212, the NFPA recognized that different types of occupancies exhibit varying degrees of potential for fire. Similarly, the need for egress can be related to the hazards associated with the work process or type of facility and equipment. Therefore, the proposed standard includes, as has the Life Safety Code,  paragraph 4-213, more extensive requirements for those workplaces where there may be a greater propensity for emergencies.
In consideration of the comparative speed of egress when using ramps, stairs, horizontal exits, and ladders, it seems reasonable to require the lowest ratio of workers to unit exits for ladders and the highest ratio to horizontal exits. Results from studies to validate the specific ratios selected are not available; these ratios were previously recommended by NFPA  and on review, professional judgment indicates that they are reasonable and should be required. The standard recommends provisions for dual egress from elevated workstations 15 or more feet above grade or floor level with a designed occupancy load of 10 or more workers. inches as a sufficient representation for emergency egress purposes of the width of a worker. This unit is used by the NFPA in their code and is judged to be a reasonable value despite the fact that it will not be a comfortable width for some workers.
During the development of the proposed standard no data were found which indicated a definite quantitative relationship between the effects of the lack of emergency egress and the need for it. Therefore, a conservative approach has been taken to provide increased protection for workers who are exposed to the hazard associated with the need for emergency egress from elevated workstations.
V I I . Crude petroleum and natural gas extraction, construction, chemicals and allied products, petroleum refining, metal industries (includes blast furnaces, steel works, rolling and finishing mills, other primary iron and steel industries, primary aluminum industries, other primary nonferrous industries).
Taken from 1970 Census data  - U S G P O : 1 9 7 5 -6 5 7 -6 4 5 /2 1 7

# PUBLIC HEALTH SERVICE C E N T E R FO R D IS E A S E C O N T R O L N A T IO N A L IN S T IT U T E FO R O C C U P A T IO N A L S A F E T Y A N D H E