In selecting a respirator, the most critical determinant is the nature and degree of possible hazard.

• A. The nature and degree of possible hazard
• B. The comfort of the user
• C. The cost of the apparatus
• D. The brand of the respirator

Answer: (A)

The most important factor when choosing a respirator is understanding the hazard you may face: what contaminant is present, its form (dust, vapor, gas, or a combination), and how much exposure is possible. That information drives the type of respirator and the level of protection required. For example, particulates demand a filtration option appropriate to the particle size and concentration, while gases or vapors require cartridges or a supplied-air system with the correct chemical filter. The selected respirator must provide sufficient protection for the expected exposure level (considering factors like duration and concentration) and must be fit-tested and seal-checked to ensure effective protection. Practical aspects like comfort or cost matter for compliance and consistent use, but they do not determine safety—hazard assessment does. Brand is secondary to whether the respirator meets the protection needs for the identified hazard.