Which of the following can indicate the need for respiratory protection?

The need for respiratory protection is primarily indicated by low oxygen levels. In environments where oxygen concentration falls below safe levels, individuals risk asphyxiation, making respiratory protection essential. Oxygen deficiency can occur in confined spaces, during certain chemical reactions, or in areas where oxygen displacements happen, such as those involving inert gases.

While strong odors may suggest the presence of hazardous materials, they do not reliably indicate a need for respiratory protection, as some substances may not emit noticeable odors. Clear visibility does not provide any information regarding air quality or the presence of harmful agents, and high noise levels pertain more to hearing protection rather than respiratory safety. Therefore, low oxygen levels directly necessitate the use of respiratory protection to safeguard an individual's health and safety.