What are the two primary types of respirators?

The two primary types of respirators are air-purifying respirators (APRs) and supplied-air respirators (SARs). Air-purifying respirators filter out contaminants from the air, such as particulate matter or gases, and are used in environments where the air is still breathable but contaminated. In contrast, supplied-air respirators provide a fresh supply of air from an external source, making them suitable for use in highly hazardous environments where the air quality is not safe to breathe.