When evaluating a PAPR, prioritize the Assigned Protection Factor (APF), which typically ranges from 25 to 1,000 depending on the hood design. Ensure the Airflow Rate meets a minimum of 170 L/min (6 CFM) for loose-fitting facepieces to maintain positive pressure. Additionally, check the Battery Life, aiming for at least 8-12 hours of continuous operation to cover a full work shift, and verify that the Filter Efficiency matches your specific hazard (e.g., HEPA/P100 for particulates or specialized cartridges for organic vapors).