Fuerzas de Elite

International Standards for Mine Action are being revised by the United Nations. As part of the revision process, a working group on personal protective equipment (WGPPE) has been established to examine the subject of safety in mine clearance operations, and to make recommendations on standards and guidelines for PPE. This paper is based on the WGPPE's report.

The concepts of safety, risk and risk management are not new to humanitarian mine clearance. Risk management involves the identification, analysis, assessment and removal (or at least reduction) of risk. The term implies dominance and control of the risk, and the application of agreed processes to achieve consistent results.
It is necessary to clarify the meaning of the term safe in respect of mine clearance. To say that a situation is safe implies a final judgement that the risk is in some sense acceptable or tolerable, or even non-existent. However, the terms "acceptable" and "tolerable" imply human judgement of the situation - and judgement may be tentative, transient and fallible.

A Systems Approach to the Problem
A recent international study of mine accidents and incidents carried out by Andy Smith on behalf of the U.S. Department of Defense (DoD) has revealed that in the vast majority of cases, victims either failed to wear PPE correctly or were engaged in activities which contravened local Standing Operating Procedures (SOPs). A simple statement of the blast and ballistic protection levels alone would be inadequate for international safety standards. A systems approach considering the threat, training, operating procedures, supervision, equipment capabilities, environmental factors and protection levels is needed to enable managers of mine clearance operations to decide appropriate local requirements for PPE.

Mine and UXO Threat
Though the term "threat" is not often found in general safety literature, it is frequently used in mine clearance to describe the extent of risk at a particular time in a particular country, province or district. Threat is a useful concept and we must establish a common understanding of its meaning and application.
Whereas "risk" refers to the probability and severity of a single occurrence of harm, the threat from mines and UXO refers to the sum of local risks in an area or theatre. In mine clearance, the probability of harm is a combination of the quantity of munitions with the potential to cause harm and the probability of failing to detect a single active mine/UXO. There seem to be three components of any threat within a given area: (1) The type of hazard (fragmentation, blast or incendiary), and the severity of physical harm which would result from its unintended detonation; (2) The detectability of mines and/or UXO; and (3) The quantity of mines and/or UXO within a given area.
Threat is dependent on time as well as area. In some mine-affected theatres it will reduce over time from demining and through effective mine awareness training. In other theatres it may increase over time from uncontrolled vegetation coverage, soil movements and the cumulative effects of weather.

Table 1: AP mine threat, MND(SW) Bosnia-Herzegovina


The threat can be demonstrated graphically as shown in Table 1 above. This example, which uses data from Bosnia-Herzegovina, attempts to illustrate the antipersonnel (AP) mine threat in Sector MND(SW). In general, mines towards the top right of the table represent a greater threat than those towards the bottom left. The size of the circle is proportional to the quantity of mines.
Risk Management
In recent years the concepts of risk, risk management and safety have received much attention from industry and academia. This attention can be explained in part by a moral imperative and by a growing sense of duty, but it is mainly driven by the impact of litigation. The International Organisation for Standardization (ISO) has had to address these issues in the workplace. ISO guidelines for the development of safety standards are relevant, and the ISO approach has proved to be an appropriate model to guide the work of the WGPPE.
Notwithstanding the legal imperatives to reduce risk, humanitarian mine clearance imposes a moral duty of care that demands attention be given to the consequence of all actions, and also to the consequence of inaction. The latter is often overlooked, and is particularly relevant to those in positions of authority, supervision or of professional standing in humanitarian mine clearance.

Health and Safety
The International Labour Organisation (ILO) is a specialist agency of the United Nations, which seeks the promotion of human and labor rights. The ILO formulates international standards in the form of Conventions and Recommendations by setting minimum norms, including basic standards regulating conditions of work and the workplace. In 1981, the ILO adopted a Convention (C155) and related Recommendation (R164) on Occupational Safety and Health.
Precedent and norms already exist at the international level to provide guidance for the development of new international standards for safety in mine clearance. The concept of responsibility included in ISO and ILO documents implies the need for accountability. In particular, the responsibilities and obligations of the national authorities, mine action centers, the employers and employees as required by the ILO should be applied to the management of mine clearance and be included in the revised safety standards.

Mine Incidents and Accidents
Risk reduction involves a combination of safe operating procedures, education, training, effective supervision and PPE. In adopting a systems approach, the WGPPE considered it necessary to analyze and evaluate the relationships between these factors before deciding whether the residual risk to deminers is "tolerable." This conforms to the approach taken by ISO in developing safety standards.
Much of the WGPPE's analysis and many of its conclusions on PPE have been derived from the Database of Demining Incident Victims (DDIV) compiled by Smith. The database covers mine clearance incidents in Angola, Afghanistan, Cambodia, Bosnia-Herzegovina, Mozambique and Zimbabwe.
The DDIV is a record of explosive incidents involving deminers. The victims were employed by NGOs, commercial demining companies, national agencies and in some cases the military. The current release (Version 1) of the database contains the records of 319 victims and 249 incidents.

Mine and UXO Hazards
AP blast mines are the most abundant mines encountered in humanitarian mine clearance and cause the greatest number of injuries. At close quarters, AP fragmentation mines overmatch the PPE currently available. Due to the area effect of such mines they also have the potential to effect secondary victims. AT mines normally require significant pressure to detonate and are less hazardous to manual deminers unless employed a non-conventional manner. Effective PPE against AT mines is not available.
In general, when UXO munitions are encountered in mine clearance operations, they have already malfunctioned, though some are specifically designed as area denial weapons. They are usually high in metal content, on or near the surface. Since most are easily detectable, they constitute less of a hazard than mines. When the threat from "advanced UXO" exists, specialist EOD teams should be used. The varied nature of UXO means that the hazard is best dealt with procedurally, rather than relying on PPE designed primarily for humanitarian mine clearance.
The effect of blast is roughly proportional to the explosive content, though it can vary according to the mine's construction. The PMN (240g) is an appropriate level to protect against, as it is one of the most common mines found in reported incidents. Most mines with larger charges (PROM-1, V69) are fragmentation mines, and the lethality of their fragmentation effects is more significant than blast.
Fragment sizes and velocities vary greatly, even from mines of the same type with grooved/notched casing. DDIV analysis shows a high percentage of fatalities from fragmentation mines (52 percent of bounding fragmentation mine incidents and 22 percent of fragmentation mine incidents); survivors were usually secondary victims. Current PPE levels do not protect against close proximity fragmentation mines, but may protect secondary victims.
There is also a fragmentation hazard from the casing and inner components of some AP blast mines. Furthermore, AP blast mines buried in scree, gravel roads and tracks, and in soil containing a high percentage of stones, represent a particular challenge for PPE.
Harmful Activities
The most common mine clearance activities which led to harm were excavation (36 percent) and missed-mine incidents (26 percent). Excavation includes digging with any tool or investigating a previously located mine; a missed-mine incident occurs when a victim initiates a device which the deminer or any other member of the demining unit has failed to locate. While excavating, almost all deminers were injured in the squatting or kneeling position.
Less than 10 percent of incidents involved deminers (mis)handling or holding the mine during examination or disarming. Nearly seven percent of incidents involved behavior considered dangerous or careless, such as stepping outside a cleared and well-marked area.
Only two percent of all incidents involved an accident during detection. It should be noted, however, that this low figure may disguise the practice of "detection by excavation" which is sometimes applied.

Areas of the Body at Risk
The DDIV classifies non-fatal injuries as severe if they were likely to be life threatening, to require surgery or to result in permanent disability. All other injuries are classified as minor. The distinction is not intended to reflect the suffering and/or hardship associated with any injury. The areas of the body at risk are summarized in Table 1 below.
Table 1: Areas of the Body at Risk
Severe Minor Total
Head and neck: 94 148 242
Upper Limb: 92 142 234
Lower Limb: 109 98 207
Trunk: 40 77 117
The risk of severe injuries to the head and to the limbs (both upper and lower) is similar, but the risk to the trunk is not as severe. The majority of head and upper limb injuries were caused while excavating and from (mis)handling incidents, whereas the majority of lower limb injuries were caused by missed-mine incidents.
(Note: The lower number of injuries to the trunk cannot be explained by the provision of PPE since the DDIV suggests that in the majority of cases the victims were not wearing any body protection).
Environment
The diversity of environmental factors make it difficult to generalize about their impact on safety as a whole, and on PPE in particular. Climatic extremes are a constant concern in some theatres through high temperature, humidity or cold. In addition, there may be local environmental problems which demand use of specialized PPE or life support equipment.

Analysis and Discussion
Perception(s): It is often assumed that minimum metal mines represent the greatest risk to deminers as they are, at least in theory, the most difficult to detect. However, this assumption is not confirmed by the number of reported injuries. The majority of missed mine incidents involve a PMN, PMN 2 or PPM-2; and all have significant metal content. There may be a psychological "risk adjustment", which causes deminers to operate with greater caution in areas where minimal metal mines are expected.
Fatalities: Incidents resulting in death show a disproportionate number resulting from bounding fragmentation mines. AP blast mines account for the next greatest number, followed by larger mines. Vegetation clearance produced the highest number of deminer fatalities. Handling or manipulating mines (some during the process of disarming) proved to be the second highest readily identifiable activity at the time of death.
Injuries: Evidence suggests that AP blast mines were the most common cause of deminer injury (62 percent), of which the PMN and PMN-2 series caused 38 percent of the incidents.
Protection: A fragmentation jacket or apron of some kind was issued to under a third of the victims recorded in the DDIV. It was worn in only half of those cases, and visors were temporarily discarded or raised by 56 percent of the victims issued with them. The thickest visors commonly worn were 5mm thick. These appeared to provide adequate protection against blast and were considered wearable by deminers. There was also evidence of severe hand injuries resulting (at least in part) from the use of inappropriate hand-tools during manual demining.

Risk Reduction
Risk Management: Risk reduction involves a combination of factors including safe operating procedures, education, training, PPE and effective supervision. Though international guidelines and national SOPs can provide advice on how this can be achieved, the responsibility for risk management lies principally with the employers be they national teams, demining NGOs or commercial contractors. This responsibility must be embedded in the management culture and practices of all organizations involved in the planning and prosecution of humanitarian mine clearance operations.
Control and supervision: There is much room for improvements in the control and supervision of humanitarian mine clearance operations. Over 50 percent of the injuries recorded in the DDIV were apparently caused by inadequate "field control." Improved field discipline and control through education, training and supervision would reduce the risk to deminers. It would also increase the overall efficiency of clearance operations. An accident causes substantial dislocation and delay, in addition to the obvious injuries to the victim, and to the socio-economic impact on his family and community.
Reports and Investigations: There is significant variation in the quality and timeliness of reports and post-incident investigations. Consideration should be given to the development of an international standard for reporting and for the conduct of investigations and inquiries. Though local requirements may vary, there is a need to maintain objectivity and impartiality, and to facilitate lessons learned about risk and safety issues.
PPE Requirements
Human Factors: The frequency with which deminers fail to wear PPE suggests that equipment and clothing is either inappropriate, or is already at or beyond the "wearable" limits of weight and mobility, though some improvements could be achieved through better field discipline. Any assessment of PPE requirements must recognize the limits of acceptability by addressing the human factors, including environmental conditions and ergonomics.
Associated Equipment: The systems approach to risk reduction includes an understanding of the interface between the deminer and his/her associated equipment. In this respect, the selection and use of hand-protection and appropriate hand-tools is particularly important, and should be considered as an integral part of the PPE requirement.
Blast: The explosive content of a PMN is "… just under the threshold for overpressure injuries." Larger explosive content is generally confined to fragmentation mines, where the lethality of fragmentation is more significant than blast. The DDIV provides no evidence to suggest the need to protect against overpressure from AP blast mines, yet tests conducted by Canadian Defence Research Establishment Suffield (DRES) suggest the possibility in certain cases of "… severe, critical or unsurvivable injury."
Fragmentation: Current accepted levels of PPE provide inadequate protection against fragmentation mines at close quarters, and procedures/processes must be applied (with conviction) to reduce the risk to a tolerable level. PPE should continue to be designed to protect "secondary victims" against fragmentation mines.
Boots: Blast-resistant boots which are designed with at least a 10cm stand-off may reduce injuries when stepping on small blast mines, but they impair mobility and are unlikely to be accepted for general use though they may have some specialist application. There is no clear evidence to suggest that blast-resistant mine boots, without any stand-off, would reduce injury to an acceptable level. Indeed, some evidence suggests that such boots may actually worsen the severity of leg and groin injuries when stepping on a PMN. Further evidence from study and independent tests is required to determine the efficacy of blast-resistant mine boots, and so judge their place in humanitarian demining operations.
Requirement(s): PPE is the final protective measure after all planning, training and procedural efforts to reduce risk have been taken. Deciding appropriate PPE depends heavily on local SOPs, and should be the subject of an iterative risk reduction exercise using a formal process as set out in ISO Guide 51. A realistic minimum standard for PPE is that capable of withstanding the effects of blast and fragmentation mines as shown in Box 1 below.
Formal Evaluation: There is a need to encourage the formal trials of PPE available for use in humanitarian mine clearance programs. Such a trial should be conducted under strictly controlled and repeatable conditions using criteria that agrees with the field user community. Ideally, this trial should be conducted with United Nations approval and taken as a priority project by the recently formed International Test and Evaluation Programme (ITEP). The results should be made available to MACs and demining entities in the form of a consumer report.

User Trials: User trials complement formal testing and evaluation. They serve two purposes. First, they provide a means of testing locally manufactured or locally modified PPE against local threats without involving the cost and complexity of a formal international trial. Second, they provide local demining entities with immediate and sometimes more appropriate results under local test conditions. They encourage local confidence in the effectiveness of PPE.
Blast: PMN mine detonating during demining in a squatting/kneeling position:
•Frontal protection, coverage appropriate to the activity, capable of protecting against the effects of a 240g of TNT at 30cm from the closest part.
•Eye protection equal to that offered by 5mm of untreated polycarbonate, capable of retaining integrity against the effects of 240g of TNT at 60cm, (providing full frontal coverage of face and throat in conjunction with jacket/apron).
•Hand protection integrated into the appropriate design of hand-tools. The tools should be designed to be used at a low angle to the ground, provide at least 30cm stand-off from an anticipated point of detonation, and be constructed in such a way that their separation or fragmentation in a blast is reduced to a minimum and include a hand-shield whenever possible.
Fragmentation: Ballistic protection of "secondary victims" must be provided against the local fragmentation mine threat. It is generally acknowledged that tests for ballistic protection do not realistically replicate mine effects. Until an accepted alternative is developed as an international standard, the effects of a fragmentation hazard should continue to be evaluated by the STANAG 450 m/s V50 test or by independently verified user trials (involving at least three articles of equipment) tested at the safe working distances defined in local SOPs.
Box 1: Minimum PPE requirement

CONCLUSION
In examining the vital demining issue of PPE and its effectiveness, it's crucial not to overlook outside factors. While the study of PPE certainly must focus on its adherence to international standards, durability in the field and proper usage by deminers, through efforts like those of the WGPPE, these factors are integrated with other vital forces. These forces include environment, threat and supervision, among others. When all factors are considered, the most efficient and, above all, safe approach toward reducing risk is revealed. Also, not to be overlooked are industry practices outside the realm of demining. If SOPs are to be improved, the demining community may need to look no further than other successful risk-laden industries. The end result of an intelligent and comprehensive study of PPE and its surrounding influences will inherently address issues such as the effects of primary and secondary fragmentation, threats from lesser detectable mines and areas of the body most at risk. But only through examination of the broader picture can those issues that hit home the hardest be understood and corrected.

Un saludo

CHUSKI

_________________
Que la fuerza te acompañe
__________________________

APPENDIX C
PAPR- AND CLOTHING-LIMITED STAY TIMES

This appendix is adapted from NBC Protection, Department of the Army Field Manual No. 3-4, U.S. and Marine Corps Fleet Marine Force Manual No. 11-9, FM 3-4/FM 11-9, Washington, DC, May 1992, and Sustaining Health and Performance in the Desert: A Pocket Guide for Operations in Southwest Asia, Technical Note 91-2, prepared by the Staff of the U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts, December 1990.

IMPORTANT NOTE: While the principles in this appendix are highly relevant to the situation faced by CSEPP emergency responders, there is one very important difference. This appendix is based on the U.S. Army’s approach to PPE called Mission-Oriented Protective Posture (MOPP) which allows the level of protection to be varied depending on the situation. For instance, personnel may be allowed to unzip their protective clothing or roll up their respirator hoods under certain circumstances. This approach is not acceptable for CSEPP civilian responders. All CSEPP civilian responders wearing PPE must maintain the maximum level of protection provided by the clothing and respiratory equipment at all times when they are in a potential hazard area. Therefore the CSEPP PPE is equivalent to MOPP 4 for the purpose of assessing limited stay times.



PAPR LIMITED STAY TIMES

The following calculation is used to determine how long an emergency worker wearing a respirator can safely remain in a potentially contaminated area based on the time-weighted average concentration to which the worker will be exposed:

• Estimate the maximum unprotected stay time by multiplying the Occupational Exposure Limit for the agent (see Table C.1) by the time-weighted interval (8 hours or 480 minutes) and then dividing the result by the airborne chemical agent concentration in the area where the worker is assigned.

• Multiply the maximum unprotected stay time by the respirator protection factor to estimate the maximum time the worker can remain in the area while wearing the respirator.

Table C.1. Occupational Exposure Limits for Chemical Warfare Agents

Agent Occupational Exposure Limit (8-hour TWAa)
GA/GB 0.0001
VX 0.00001
HD/L 0.003b

aTWA = time-weighted average.
bValue represents technologically feasible real time detection limit.

For example, the time-weighted-average exposure limit for GB is 0.0001 milligram per cubic meter (mg/m3) and the time-weighted interval is 8 hours. At a maximum airborne concentration of 0.2 mg/m3 (the IDLH level of GB), the unprotected stay time is 0.24 min [(0.0001 mg/m3 × 8 hr × 60 min/hr)/
(0.2 mg/m3)], based on a time-weighted-average exposure. Assuming an assigned respirator protection factor of 50, the resulting stay time would be
12 min (50 × 0.24 min). Lower airborne chemical agent concentrations or larger protection factors would yield proportionately longer stay times.

The limit on the stay time based on the capacity of the respirator cartridge can be estimated by the following rule-of-thumb used by the U.S. Army:

• Multiply the cartridge service life (16 hours or 960 minutes) by the agent concentration at which it was tested (0.5 mg/m3) which yields a total dosage of 480 mg-min/m3.
• Divide the total dosage capacity of the cartridge by the airborne chemical agent concentrations in the area where the emergency worker is assigned to estimate the maximum stay time based on the cartridge capacity.

Continuing the above example, at an airborne concentration level of 0.2 mg/m3, the stay time based on cartridge capacity would be 2,400 min or 40 hours
[(480 mg-min/m3)/(0.2 mg/m3)]. Consequently in this example the emergency worker stay time in an area with an airborne concentration of GB of 0.2 mg/m3 would have to be limited to 12 minutes, the smaller of the two restrictions on the stay time (40 hours vs. 12 minutes).


CLOTHING LIMITED STAY TIMES

Heat Stress Factors

Guidelines for reducing heat stress should be followed whenever protective clothing and equipment is used. Body temperature must be maintained within narrow limits for optimum physical and mental performance. The body produces more heat during work than rest. Normally, the body cools itself by evaporation of sweat and radiation of heat at the skin’s surface. PPE restricts these heat loss mechanisms because of its low permeability to water vapor. In addition, physical work tasks require more effort when workers wear protective clothing because of added weight and restricted movement. This results in more body heat to be dissipated than normal and body temperature tends to rise quickly. The amount of heat accumulation depends upon:

• the amount of physical activity
• the level of hydration
• the clothing worn
• the load carried
• the state of heat acclimatization
• physical fitness and fatigue
• as well as terrain and weather conditions.

Adjusting the level of heat stress by (1) unzipping the protective suit,
(2) unbuttoning and loosening overshoes, (3) rolling back the PAPR hood, and so forth will reduce barriers to body cooling. These adjustments can only be made when outside the hazard area.

Work intensity is a major contributing factor to heat stress that can be managed in the field. Work tasks can be characterized as very light, light, moderate or heavy; Table C.2 provides examples of tasks that can be used as a guide in estimating the work intensity for a particular emergency worker task. In an emergency situation, work/rest cycles may offer no advantage to continuous work; for example, when the environmental and clothing conditions do not permit PPE to be adjusted or removed, during rest breaks).

The calculated PAPR and clothing tolerance times (Table C.3) can be used to limit the risk of heat casualties. Although strict adherence to work/rest criteria is possible during training exercises, this may not be possible during an emergency situation.

These estimates, representing average expected values within a large population, should be considered approximate guidance and not be used as a substitute for common sense or experience.

Table C.2. Work intensities of tasks
Work Intensity
not wearing PPE

Activity
Work Intensity
wearing PPE

Very Light
Standing on ground
Sitting in truck
Driving truck
Very Light

Light
Walking hard surface [1 meter per second (m/s) no load]
Walking hard surface (1 m/s, 20 kg load)
Walking hard surface (1 m/s, 30 kg load)
Light
Moderate

Walking loose sand (1 m/s, no load)
Walking hard surface (1.56 m/s, no load)
Calisthenics

Moderate

Walking hard surface [1.56 m/s, 20 kg
(44 lbs) load]
Patrol
Pick and shovel
Heavy

Heavy
Walking hard surface [1.56 m/s, 30 kg
(66 lbs) load]
Walking hard surface (2.0 m/s, no load)
Walking hard surface (2.25 m/s, no load)
Walking loose sand (1.56 m/s, no load)
Heavy

The work intensity categories of this table are based on metabolic expenditures.

Very light = 105 to 175 watts
Light = 172 to 325 watts
Moderate = 325 to 500 watts
Heavy = 500 + watts

A watt is a unit of power, equal to one joule per second. A joule is a unit of energy equal to 0.239 calories.

The weight of the chemical protective overshoe is a primary contributor to increased work intensity in MOPP.

Source: Adapted from USARIEM 1/11/91.



Table C.3. Clothing Limited Stay Times1
Temperature Range Work Time Rest Time

50 – 70°F/10-21°C
70 – 85°F/21-29°C
85 – 100°F/29-38°C
30 – 45 minutes
20 – 30 minutes
15 – 20 minutes
10 –15 minutes
40 – 60 minutes
indefinite
1Must use Wet Bulb/Globe Temperature.

Dehydration

Because of higher body temperatures, individuals in PPE sweat considerably more than usual, often more that 1.5 quarts of water every hour during work. Water must be consumed to replace lost fluids or dehydration will follow. Even a slight degree of dehydration impairs the body’s ability to regulate its temperature and nullifies the benefits of heat acclimatization and physical fitness, increases the susceptibility to heat injury, and reduces work capacity, appetite, and alertness. Even in workers who are not heat casualties, the combined effects of dehydration, restricted heat loss from the body, and increased work effort place a severe strain on the body’s functions, and workers suffer declines in mental and physical performance.

The inability to drink in full PPE, as it has been modified for civilian use to include the PAPR, increases the likelihood of dehydration. Thirst is not an adequate indicator of dehydration; workers may not sense when they are dehydrated and may fail to replace body water losses. Even when drinking water is readily available, it is not possible for them to drink while in full gear. Dehydration and the need for regular and timely fluid replacement in the workers is a limiting factor on stay time in full PPE.

Psychological Factors

Wearing full PPE reduces the ability to see and hear clearly and makes it more difficult to recognize and communicate with others. This creates or increases feelings of isolation and confusion. The awkwardness and bulkiness that accompanies wearing the PPE causes frustration in many and claustrophobia in others. Experience in wearing and exercising in the PPE can reduce these feelings.

PPE reduces the emergency worker’s ability to recognize and communicate efficiently and may require dramatic changes in personal habits. All emergency workers can experience deficits in performance due to the awkwardness of PPE. Those persons inexperienced in the use of the PPE are more likely to become frustrated. Those who must perform without knowing when they will be relieved from PPE use are also more susceptible. Certain jobs are more likely to be affected than others; e.g., tasks that require clear vision, precise hearing, social and emotional support, or communication by facial expression, gestures, and inflections in voice.

Identifying emergency workers by name and job function can be accomplished through various means. One way is to use tape showing name and job function. When emergency workers are not in PPE, a strip of tape with the information already printed on it can be placed on the emergency worker’s Ready Bag. When the overgarments are put on, the emergency worker can pull the tape off the overgarment bag and place it on the overgarment to further increase ease of identification. Another method might be the use of vests as long as they do not damage or interfere with the use of other equipment and allow the workers to perform unimpeded.

Effects of Heat Stress on Performance in PPE

Emergency workers wearing CSEPP PPE will take about 1.5 times longer to perform most tasks. Decision-making and precision control tasks are slowed even more than manual tasks. For decision-making and precision control (for example, typing a message or using auto-injector) the normally expected completion time should be multiplied by 2.5 (or more, if workers have been in PPE for extended period or are overheated.).

Heat stress affects performance in many different kinds of jobs. Jobs which require physical exertion cause physiological and mental performance to deteriorate rapidly. However, mental performance of emergency workers working at sedentary tasks also deteriorates sharply over time in the heat.

Performance in the following jobs is most likely to be affected by heat stress:

• monotonous, repetitive, or boring tasks
• tasks which require attention to detail, concentration, and short-term memory
(e.g., calculations, repeating communications, etc.)
• tasks which are not self-paced (i.e., any tasks that must be done quickly or according to a fixed schedule)
• tasks which require arm or hand steadiness
• tasks where confusion, misinformation, and disorientation are common
(e.g., command, control, communications, etc.).

Performance is affected by stress in a variety of ways:

• reaction times and decision times are longer
• routine tasks are done more slowly
• errors of omission are more common
• performance of tasks which require vigilance may degrade slightly after 39 minutes, and certainly after 2–3 hours.

Use the buddy system whenever possible; a buddy can check for signs of stress and fatigue. Pair experienced buddies with inexperienced emergency workers. Critical jobs should be shared and work should be double-checked.

Cold Stress Factors

Though far less likely to be a complicating factor than is heat stress, cold stress can directly affect an individual’s health and performance while wearing PPE. Cold can lower body temperature, resulting in cold injuries and impaired performance. Cold weather is often accompanied by wind, rain, snow and ice, which can worsen the effects of cold, as well as contribute to injury and performance impairments in and of themselves. Cold weather clothing and PPE are difficult to integrate.

Hypothermia

Body temperature falls when the body cannot produce heat as fast as it is being lost. This can result in hypothermia, which is a life threatening condition in which deep-body temperature falls below 95°F (35°C). Generally, deep-body temperature will not fall until after many hours of continuous exposure to cold air, if the individual is healthy, physically active and reasonably dressed. However body temperatures can fall even when air temperatures are above freezing if conditions are windy, clothing is wet, and/or the individual is inactive.

Hypothermia can be difficult to recognize in the early stages of development. Things to watch for include:

• unusually withdrawn or bizarre behavior
• irritability
• confusion
• slowed or slurred speech
• altered vision
• uncoordinated movements and
• unconsciousness.

Even mild hypothermia can cause victims to make poor decisions or act drunk
(e.g., removing clothing when it is clearly inappropriate).

Effects of Cold on Agent Detection

The function of chemical agent detectors is degraded in the cold. Chemical agent detectors sense volatilized agent vapors. Agents do not vaporize readily when it is cold; therefore, the detectors respond more slowly in the presence of agents. The solution in the capsules of the M256/M256A1 chemical detection kit can freeze, and once frozen, thawing may not restore operability.

Effects of Cold on Performance in PPE

Wearing PPE during cold-weather operations increases the risk of injuries due to cold and even heat stress. PPE can restrict the blood flow to the fingers and areas of the face, increasing the susceptibility of these areas to frostbite and limiting the ability to visually inspect for signs of cold injury.

When PAPRs are carried to the hazard area outside the clothing at below freezing temperature, donning the cold PAPR can cause a contact freezing injury, especially if metal contacts the face.

Wearing the protective suit over heavy cold-weather clothing creates the unexpected situation where heat exhaustion becomes a real possibility for emergency workers working hard, even in cold weather. The added insulation and decreased ventilation of the protective suit can result in heavy sweating and wetting of the clothing during hard work, eventually degrading cold protection.

Agent decontamination procedures are extremely difficult under cold-weather conditions. Water and decontamination solutions can freeze and may limit effective decontamination.

Well-prepared workers suffer less stress in PPE than do persons who are less prepared. Well-prepared workers are those who are in good physical condition and have trained extensively in protective gear. Physically fit persons are more resistant to physical and mental fatigue and acclimatize more quickly to climatic heat or the heat associated with PPE gear than less fit persons.


Un saludo

CHUSKI

_________________
Que la fuerza te acompañe
__________________________