Final answer:
The physical limitations of respiratory protection can be exacerbated by the weight of the equipment and the resistance of harness straps, especially if the lungs are already experiencing increased resistance or decreased pliability.
Step-by-step explanation:
Physical limitations of respiratory protection are often related to the weight of the equipment and the resistance encountered when using harness straps. Normally, as the lungs become stiff and less pliable, the ease with which they expand and contract during breathing decreases. This is related to a concept known as lung compliance. Similarly, when there is increased resistance within the lung, such as from an ailment or external factor, the work required to breathe effectively is increased. This resistance can also be represented by the constraints imposed by respiratory protective gear, such as masks or respirators, which might feel heavier or more restrictive due to the tension of harness straps. Thus, if the lungs are experiencing increased resistance, the use of a respirator with tight straps can further exacerbate the difficulty of breathing.