Why the respirator is necessary (including when it must be worn)

A respirator is a crucial piece of equipment designed to protect the respiratory system of individuals from various harmful substances in the air. Its core principle is to create a filtering or barrier between a person's mouth, nose and the polluted air.
Whether to wear a respirator mainly depends on the type of hazard you need to protect against. The following diagram clearly illustrates this decision-making process.

The fundamental purpose of using a respirator is to prevent irreversible occupational diseases and acute poisoning.Whether to wear or not does not depend on "feeling" or "habit", but should be based on scientific hazard identification and risk assessment.