ISO/TS 16976-8:2013 呼吸用保護具 — 人的要因 — Part 8: 人間工学的要因 | ページ 7

4.3.1 一般

RPD は、1 つまたは複数の健康および安全上の危険から保護するために、個人が着用する必要があります。この保護は RPD の意図された効果ですが、RPD を着用すると、リスク関連のタスクの着用者の通常のパフォーマンスを妨げる可能性のある、意図しない悪影響が生じる可能性もあります。

パフォーマンス基準の作成者は、保護、実用性、および RPD の着用による潜在的な悪影響の間で最善の妥協点を特定する方法を検討する必要があります。異なる解決策が適用される場合、同等の妥協が可能である可能性があります。

4.7.1 一般

RPD性能基準で指定される適切な生体力学的効果を決定する際には、以下を考慮する必要があります。

• 異なるタイプの RPD および/または RPD と PPE の組み合わせを使用した場合の質量の静的分布、動的または慣性力、および結果として生じる人体への負荷、
• 作業負荷および/またはタスクパフォ​​ーマンスに対する RPD の生体力学的効果の影響の最適化。

RPD は、受動的負荷の増加または動的負荷の変化によって、筋肉の緊張またはエネルギー消費を増加させることにより、体に悪影響を与える可能性があります。たとえば、頭に質量が加わると、首の筋肉が対抗しなければならない力が首に生じます。

RPD の質量とその分布は、影響を受ける可能性のある特定の身体部分に関連して考慮する必要があります。

体や体の一部に重い塊があると、特にウォーキングやランニングの際にエネルギー消費が増加します。

このドキュメントのこのセクションの原則を、水中または異常な加速力を伴う状況で着用することを意図した RPD に適用する場合は注意が必要です。

4.8.1 一般

性能基準を作成する際には、RPD の保護機能が着用者にとって可能な限り最高の温度快適性レベルに維持されるように、人間工学的要素を考慮する必要があります。

熱交換に厳しい制限を課さないRPDが着用者の快適さと効率を大幅に改善することは明らかです.これは、適切な材料の選択と設計によってある程度達成できます。

可能な限り、RPD は、覆われた身体部分が必要な場合に良好な換気と水分交換を維持できるように設計する必要があります。たとえば、吐き出された空気からの水分の凝縮は、多くの形態の RPD で発生し、局所的な熱的不快感を引き起こす可能性があります。

着用者の熱交換に対する全体的な影響は、熱環境、活動、衣服、RPD の間の相互作用によって異なります。したがって、ＲＰＤまたは複合ＲＰＤと作業着および／またはその他の衣服は、定義された活動レベルの環境条件の上限および下限を有し、その範囲内では使用者にとってほとんど不快ではない。そのような制限の適切な仕様、および/またはそのような制限の計算のための熱特性は、性能基準で与えられるべきです。

4 Ergonomic factors

4.1 General

Harmonized performance standards for RPD should contain ergonomic requirements and test methods, or should make normative reference to other standards to be applied.

Usually, ergonomic assessments of RPD have to be made while people are wearing them or are connected to the external component of the system. Wherever possible, the assessments should be objective, although some aspects can only be assessed subjectively.

Examples of how to make assessments are given in Annex A.

4.2 Integration of performance and ergonomic requirements

The primary purpose of RPD is to provide protection against specific inhalation hazards that cannot be eliminated or adequately reduced by other means. Performance standards should therefore contain performance requirements and test methods to ensure that the products fulfilling the performance provide the appropriate protection against the identified hazards, and that they are ergonomically suitable for the users.

Performance standards writers should consider the tasks being performed, the equipment being used, the duration of the usage of the RPD, and the environments likely to be encountered. They should ensure as far as possible that the RPD does not create hazards for the users. This may be by incorporating in performance standards requirements and test methods based on this part of ISO/TS 16976.

Where the presence of more than one risk or the need to cover more parts of the body makes it necessary for a wearer to use simultaneously besides an RPD another item of Personal Protective Equipment (PPE), such equipment must be mutually compatible and continue to be effective against the risk or risks in question.

In addition to interactive effects on technical performance, interaction between different forms of PPE including RPD may influence ergonomic aspects. Thus, although the effect of individual items of PPE tested in isolation may not be significant, it will be the combined effect that will determine the overall load and consequent acceptability. For example, both a half-mask respirator and a safety helmet may intrude upon the visual field (glasses). Either in isolation may be acceptable but, when worn together the combined impact may not be. At its most extreme, extensive body coverage by RPD, or wearing several forms of protection may result in sensory and physical isolation.

Ergonomics requirements can be taken into account by determination of performance levels on the basis of a risk assessment.

4.3 Factors to be considered in the determination of the best ergonomic solution

4.3.2 Factors to be considered in specifying the optimum level of protection to be provided

Performance standards writers should consider the following variable aspects of the use of RPD:

• the duration of use of the RPD (some RPD such as escape RPD may be worn for only a few minutes when it is perceived that a hazard is present, but other RPD may be worn for several hours or throughout a working day/shift);
• whether there are different situations in which the RPD is used, that require different amounts of the body to be covered and for various other PPE to be used in addition;
• the reasonable balance between the severity of the hazard, protection, burden and duration.

4.3.3 Factors to be considered in specifying the optimal practicability

The designs of RPD that result from compliance with performance standards should allow, as far as possible, normal pursuit of all activity within the occupational environment. To ensure this is achieved, performance standards should include test procedures and requirements based on the performance of prescribed movements, or should make normative reference to such procedures and requirements. Standards writers should, where relevant, include reference to the fact that where RPD suppliers claim mutually compatible components of PPE, the resulting combination should be tested together. Tests should be selected to represent a range of the normal movements made by wearers of the RPD while using it.

For fire fighter PPE assessment, standard writers should refer to BS 8469.^[19]

In any event they should include the following:

• understanding instructions and warnings given by the manufacturers;
• putting on, adjusting, and taking off the RPD and/or PPE;
• general activities, such as moving and communicating;
• activities specific to situations where the RPD is to be used;
• safety of the subjects.

Practical performance tests may impose physiological strains on the test subjects thus requiring stringent controls. To ensure the safety of test subjects:

• a) the test subjects should be medically examined and certified fit in accordance with ISO 12894 ^[5];
• b) ethical clearance should be obtained in accordance with Reference;^[20]
• c) the experimentation should be performed in accordance with Reference;^[20]
• d) there should be physiological monitoring of test subjects;
• e) normal safety procedures should be applied, including close supervision by trained, experienced staff, and voluntary withdrawal should be permitted at any time.

Interpretation of the results should take into account the levels of hazard against which the RPD is intended to provide protection, the inevitable burdens such RPD will impose, and the environmental conditions under which it will be used.

Guidance on the choice of movements and the overall conduct of ergonomic assessment of RPD using human subjects is given in Annex A.

For more information, see ISO/TS 16976-1 ^[9], ISO/TS 16976-3 ^[11] and ISO/TS 16976-5^[12].

4.3.4 Factors to be considered in the physiological impact of RPD

The following indicators might be considered to determine the physiological impact in relation to the use of RPD:

• heart rate,
• oxygen consumption,
• alveolar gas composition,
• breathing rate,
• body temperature change,
• sweat rate,
• fatigue or strain of muscles.

Examples where indicators might be used include where the mass of the RPD may result in an excessive burden or where the exothermic processes providing breathable air or other factors of RPD may give rise to thermal strain.

More information may be obtained in ISO/TS 16976-1 ^[9] and ISO/TS 16976-3 ^[11].

4.4 Factors to be considered in specifying requirements for the adjustability of RPD and its appropriate fixation to the body

Performance standards writers should consider whether requirements and test methods need to be included to test the adjustments and restraint of RPD. In deciding that need, they should consider the seriousness of the consequences of displacement of the RPD, and the maximum tolerable displacement. The following are examples of aspects that could be considered:

• the information and instructions for fitting and adjusting;
• the information and instructinos for doffing of the RPD;
• the adjustability and the stability of adjustments;
• determining that the RPD has been correctly fitted.

When writing a test, consideration should be given to the static and dynamic forces that might be exerted on the RPD in normal wear, and during the circumstances in which it is intended to provide protection and how these may be represented in test methods.

4.5 Factors to be considered in specifying requirements to ensure that RPD does not irritate or cause discomfort

RPD shall not irritate or cause discomfort which may later lead to injuries for the users who may come into contact with it. Factors to be taken into account include:

• whether the RPD will be in contact with the skin and how sensitive this particular area of skin is to the effects of rubbing and pressure;
• for how long the RPD will normally be in contact with the skin;
• whether the type of RPD may have sharp or hard edges or points;
• whether the bulk, hardness and position of adjustment and closure mechanisms may have a negative impact on the user;
• whether chemical composition of the material used and its by-products may affect the body;
• whether any materials likely to be used in contact with the skin are known to produce allergic reactions in a proportion of the population;
• whether any closure mechanism, or other feature, may become caught up with scalp, facial or body hair;
• whether the outer surface of the RPD could harm other people;
• whether simple visual and manual examination of the RPD is adequate for an assessment, or whether specific test methods need to be developed for assessing the hardness, roughness or other features of the RPD.

4.6 Factors to be considered in specifying requirements to take into account the anthropometric factors of RPD

In determining appropriate anthropometric factors of the intended RPD wearer group to be specified in the RPD performance standards, the following shall be considered:

• the body part(s) it will be in contact with or cover;
• the physical activities expected to be performed during its use.

The body part(s) the RPD will be in contact with will serve to identify those parts for which anthropometric data are needed. If the RPD crosses or covers a body joint, then more anthropometric dimensions should be specified based on different joint positions.

The physical activity expected to be performed during the use of RPD may alter body dimensions. This should be taken into account in specifying anthropometric dimensions in a RPD performance standard. Excessively close fitting or otherwise poorly dimensioned RPD may prevent or hinder the performance of necessary activities.

Loose fitting or bulky RPD may restrict access to working areas or may present a potential safety hazard by snagging on projections or other features of the environment.

The intended user group will need to be defined to ensure that appropriate dimensions are specified to encompass that population. Variations in size may be accommodated by means of adequate adjustment systems or the provision of size ranges as appropriate.

Because different body dimensions are not necessarily closely correlated, standards writers should consider the need to specify more than one essential anthropometric dimension in order to ensure satisfactory fit for the intended user group.

Performance standards writers should address at least the topics related to anthropometric factors detailed in ISO/TS 16976-2[ ^10] and in ISO 15537 ^[6].

4.7 Factors to be considered in specifying requirements to take into account the biomechanical factors of RPD

4.7.2 Mass distribution

Peripheral parts of the body are more susceptible to added mass than the trunk, because of the increased moment. Hence, an additional weight is best worn on the trunk and as close as possible to the body centre of gravity and as symmetrical as possible. This means that the waist is the body location where such a weight is best carried. However, this is often not practical because RPD is normally made to be worn on specific body parts in order to protect against a specific risk.

4.7.3 Restriction and prevention of movements

Heavy, close fitting, stiff or bulky material can excessively impede the bending of joints and restrict working positions and movements. Materials and products that resist movement elastically and require a continuous muscular effort acting against the elastic recoil to maintain a particular joint position can cause fatigue and injury.

4.7.4 Abrasion or compression of the skin and underlying structures

Movement of RPD against the body can give rise to redness (erythema) and, if prolonged, to abrasion. Depending upon the duration of wear, compression of the skin can cause unsightly marking. Where blood vessels or nerves pass close to the body surface or are liable to be trapped against hard (bony) body parts then further adverse effects can occur. For example, straps passing close to the neck/shoulder junction can compress nerves or occlude blood flow. Abrasion or compression might cause irritation or reduce the acceptability of the RPD. Pulse points in the neck, groin and wrist are obvious possible areas for concern in relation to circulatory effects.

4.7.5 Exacerbation of vibration

In some situations RPD, interacting with an external force, can produce vibration or shock effects. Some forms of RPD can impart additional vibration to the body of the wearer such as effects of vibration exposure, when wearing RPD during travelling in vehicles. The writers of performance standards should be aware of the special circumstances where such phenomena occur and, if appropriate, should include suitable testing within their standard.

4.8 Factors to be considered in specifying requirements to take into account the thermal effects of RPD

4.8.2 Thermal effects of materials and complete RPD

Attention shall be paid to the selection of materials for RPD which shall not only provide the required protection against the relevant hazards, but should also interfere as little as possible with body heat balance. The aim is to obtain thermal comfort and minimize thermal strain.

The performance standard writer should bear in mind that the thermal effects of multi-layer materials or of RPD enclosing the whole body may not be the same as the sum of those of the individual materials.

The performance standard writer should bear in mind that the impact of the thermal effects of the complete RPD will be influenced by the thermal environment in which the RPD is to be worn and the physical activity of the wearer.

Performance standards writers should address thermal effects by considering the information given in ISO/TS 16976-5^[12].

4.9 Factors to be considered in specifying requirements to take into account the sensory effects of RPD

4.9.1 General

The human senses are the means through which the human body receives information from the environment. Reception of the correct information is often a precondition for taking appropriate reactions. In a working situation the information can for example be about the environment, spoken information from other persons, visual information from papers, machinery or displays; feed-back from the working process; or warning signals. If the sensory signals are too weak or distorted there is a risk that they will either not be received or will be misunderstood. If the sensory signals are too strong or prolonged, the annoying effect can cause distraction, or symptoms such as fatigue and pain.

4.9.2 Vision

RPD might affect the wearer's vision adversely. Two possible examples, which are sometimes combined, are a decrease in the extent of the visual field and a reduction in optical transmission within the field of vision i.e. a reduction in the quantity or quality of visual information and the interpretation of warning signals. When designing respiratory interfaces that cover the eyes or are used in conjunction with goggles and spectacles, the impact on visual aspects should be taken into account. RPD should also be designed to allow wearers of corrective glasses to comply with the wearing of the RPD when obtaining the necessary visual correction and still achieve both protection and comfort.

4.9.3 Hearing and speech

RPD can hinder the receipt or transmission of auditory signals or information which the user either wants to hear (e.g. speech) or needs to hear (e.g. warning signals). For example, RPD may cover the ears (e.g. hooded type respiratory interface) or create disturbing noise or vibration.

Performance standards writers should address hearing and speech by considering the information given in ISO/TS 16976-7 ^[13].

4.9.4 Odour or taste

Strong odours or tastes from the RPD might create a hazard to health by masking the odour or taste of a hazardous or toxic substance. Unpleasant odour or taste can also cause discomfort either when using the RPD or, if the odour persists afterwards, it may be given as a reason for not using RPD.

4.9.5 Touch or other skin contact

Wearing RPD can have undesirable sensory effects either by impeding the acquisition of information by the sense of touch, or by creating conflicting stimuli from contact with the RPD.