Page 315 - Anthropometry, Apparel Sizing and Design

308 Anthropometry, Apparel Sizing and Design

Given that maximum protection may be worn for clothing covering the largest part of
the human body, inappropriate materials may cause comprehensive or local discom-
fort. Increased thermal insulation and evaporative resistance may result not only in
overheating but also increased sweating, which can lead to sweat-soaking and clothing
adhering to different areas of skin. This may result in additional unpleasant feelings
(such as irritation, tickle, pressure), as well as limited movements, as the clothing can
no longer be freely passed over the surface of the skin during movements. The char-
acteristics of the materials to be taken into account for thermal comfort are thermal
insulation, water vapor resistance, water vapor permeability, air permeability, water
absorption, and desorption (EN 13921:2017, 2017).

11.5.1 Weight and bulkiness
Initially, the use of relatively large values of ease allowances in developing loose
clothing without any limitation of movements may seem a simple solution to provide
the fit and also the dynamic fit of clothing, but it is essential to look for a balance
without making the clothing excessively wide, which may, on the contrary, negatively
affect the wearer’s comfort. For example, it can result in excessive folds that may limit
movements of the body, and the excessive volume can serve as a risk factor to catch on
work equipment or, even worse, on moving mechanisms. Heavy, close-fitting, stiff or
bulky material can excessively impede the bending of joints and restrict working posi-
tions and movements. Materials and products that resist movement elastically and
require a continuous muscular effort acting against the elastic recoil to maintain a par-
ticular joint position can cause fatigue and injury (EN 13921:2017, 2017).
The design of very wide and loose clothing can increase the total weight, which
leads to the fatigue of the wearer carrying it all on the body during the work. In addi-
tion, in most cases there is no possibility of choosing lighter material for solving the
clothing weight issue, considering the various protective properties that the materials
of protective clothing should have, preserving the wearer from different hazards such
as hits, cuts, dust, harmful substances, radiation, etc.
PPE designers must have knowledge of 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 center of gravity. This means that the waist is the body location where such
a weight is best carried. However, this is often not practical because PPE is normally
made to be worn on specific body parts in order to protect against a specific risk.
Asymmetric loading should be avoided as far as possible (EN 13921:2017, 2017).

11.5.2 Clothing layer interactions
Frequently protective clothing is worn above the base layers of clothing, and wearers
are also provided with multilayer protective clothing systems for more complete pro-
tection. In such cases, the selection of appropriate textile materials will be critical,
when possible interactions of the interlayers are taken into account. Additional con-
siderable factors are also the vapor resistance and air permeability of the textile