AAMI PB70 is the standard that assigns isolation gowns a barrier protection level from 1 to 4. Levels 1–3 are rated by AATCC 42 water impact penetration and AATCC 127 hydrostatic pressure; Level 4 adds a seam and closure requirement tested with the ASTM F1671 viral penetration method.
| Level 1 | Level 2 | Level 3 | Level 4 | |
|---|---|---|---|---|
| AATCC 42 (impact penetration) | ≤ 4.5 g | ≤ 1.0 g | ≤ 1.0 g | ≤ 1.0 g |
| AATCC 127 (hydrostatic pressure) | — | ≥ 20 cm | ≥ 50 cm | ≥ 50 cm |
| Seam/closure test | — | — | — | ASTM F1671 |
| Typical use | Basic care, visitors | Blood draws, suturing | Arterial draws, ICU, pathology | High-fluid-risk surgery, suspected infectious body fluids |
When to use each level
- Levels 1–3 — rated by the fabric alone; pick the level by the amount and pressure of fluid the task is expected to produce.
- Level 4 — the key difference is that the seams and closures are also tested for viral penetration, not that the fabric is thicker.
Frequently asked questions
What is the difference between AAMI Level 3 and Level 4 isolation gowns?
Levels 1–3 rate the fabric only; Level 4 rates the fabric and the seams and closures.
Does a Level 4 gown weigh more than a Level 3 gown?
Not necessarily — the level describes barrier performance, not weight or thickness.
Is AAMI PB70 the same as EN 13795?
No — separate standards, separate test methods.