What criterion is used to rate respirators?

The correct answer focuses on the criterion of the size of the particle filtered. This is crucial because respirators are designed to protect the wearer from inhaling hazardous particles, including dust, aerosols, and chemical vapors. The effectiveness of a respirator is largely determined by its ability to filter out particles of specific sizes, as different types of respirators are rated for various particle sizes based on standards established by organizations such as the National Institute for Occupational Safety and Health (NIOSH).

Respirators are classified into different categories, such as N95, P100, etc., indicating their filtration efficiency against airborne particles. A respirator rated N95, for example, filters at least 95% of particles that are 0.3 microns in size. These ratings directly inform users about the level of protection they can expect when using a particular respirator, making the size of the particle filtered a fundamental aspect of respirator safety and effectiveness.

Other mentioned criteria, such as breathability, noise level, and weight of the mask, do play roles in user comfort and usability but do not directly determine the respirator's primary function of particulate filtration. Hence, while those attributes contribute to the overall effectiveness and user experience, they do not define the protective