Which type of respiratory protective device typically provides around 60 minutes of air supply?

The self-contained breathing apparatus (SCBA) is the correct choice because it is specifically designed to provide a user with a breathable air supply in hazardous environments, such as those involving toxic gases or low oxygen levels. SCBAs contain their own air supply and typically can last around 30 to 60 minutes, depending on the size of the air cylinder, the user's physical activity, and the specific design of the unit. This makes them ideal for situations where the air quality is compromised, offering the necessary protection for first responders and hazardous materials technicians.

In contrast, air purifying respirators only filter existing air and do not supply fresh air, making them unsuitable for environments with dangerous contaminants. Air line respirators require an external air source and are often used in situations where there is a continuous supply of safe air, thereby not providing an independent air supply like an SCBA. Disposable respirators, while useful for protection against particulate matter, do not contain air supplies and are not suitable for extended use in hazardous atmospheres. Thus, self-contained breathing apparatuses stand out for their ability to provide a reliable air supply in emergency situations.