ANSI/AAMI PB70 is the standard that puts a number on how well a gown or drape resists liquid. It defines four levels. The level is not a quality grade and it is not a price tier. It is a statement about a test result in a defined zone of the garment, and it tells you which clinical situations the gown is built for.
The Four Levels in One Table
| Level | Typical use | Test | Pass criteria | Usual construction |
|---|---|---|---|---|
| Level 1 | Basic care, standard isolation, cover gown for visitors | AATCC 42 impact penetration | 4.5 g or less | SPP or light SMS, 25 to 35 gsm |
| Level 2 | Blood draw, suturing, ICU, pathology lab | AATCC 42 and AATCC 127 hydrostatic pressure | 1.0 g or less, 20 cm or more | SMS, 35 to 45 gsm |
| Level 3 | Arterial blood draw, IV insertion, trauma, most surgery | AATCC 42 and AATCC 127 | 1.0 g or less, 50 cm or more | SMS 45 gsm, often reinforced |
| Level 4 | Long fluid intense procedures, known pathogen exposure | ASTM F1670 blood, ASTM F1671 viral penetration | No penetration | Poly laminated SMS or breathable viral barrier laminate |
Where the Level Applies: the Critical Zone
PB70 does not require the whole gown to pass the level. It defines a critical zone: the front of the body from chest to knees, and the sleeves from cuff to above the elbow. That zone must meet the stated level. The rest of the gown, the back and the outer areas, must meet at least Level 1. This is why a Level 3 gown can be an SMS gown with reinforced panels sewn or welded onto the front and sleeves, and why the reinforcement is not a marketing extra but the part of the gown the test is run on.
When you read a spec, look for the words critical zone and check that the reinforcement drawing matches the zone. A gown described as Level 3 with reinforcement only on the chest is not a Level 3 gown.
What the Tests Actually Do
AATCC 42, Impact Penetration
Water is sprayed onto the fabric from a set height and the blotter behind it is weighed. The gain in grams is the result. Lower is better. Level 1 allows 4.5 g, Levels 2 and 3 allow 1.0 g.
AATCC 127, Hydrostatic Pressure
Water pressure is raised against the fabric until it seeps through. The height of the water column in centimetres is the result. Level 2 needs 20 cm, Level 3 needs 50 cm. This is the test that separates a Level 2 isolation gown from a Level 3 surgical gown.
ASTM F1670 and F1671
Level 4 is different in kind. F1670 uses synthetic blood under pressure. F1671 uses a bacteriophage as a surrogate for a virus. Any penetration is a fail. Only a laminated or film barrier passes, which is why Level 4 gowns are poly laminated or use a breathable viral barrier laminate rather than plain SMS.
How to Write the Level into a Spec
- State the level and the standard: AAMI PB70 Level 3, not "surgical grade".
- State the material and gsm for the body and for the critical zone separately if they differ.
- State the test reports you want with each lot: AATCC 42 and 127 for Levels 1 to 3, F1670 and F1671 for Level 4.
- State the sterility and the pack: EO sterile to ISO 11135, double wrap with two hand towels, or non sterile bulk.
- State the closure and cuff: neck tie or hook and loop, waist belt, knit cuff, thumb hook.
- State sizes, colour and the artwork for private label.
A factory can price this in a day. A request that says "Level 3 gowns, best price" cannot be priced without a conversation, and the conversation is where mistakes are made.
Common Mistakes We See
- Buying a Level 2 isolation gown for a procedure that needs Level 3 because the price looked right.
- Accepting a certificate for the fabric roll as proof for the finished gown. Seams and reinforcement matter. Ask for a finished garment test.
- Confusing AAMI levels with EN 13795 performance classes. They are related but the tests and the zones differ. Our EN 13795 guide covers this.
- Treating the level as a brand attribute. The gown on a distributor's shelf and the gown from the factory that made it carry the same level because they are the same gown.
Where to Go from Here
Every gown on our protective apparel page is listed with its level, its tests and its construction, and the level selector shows the spec change as you move from Level 1 to Level 4. The test reports for each lot sit on the Trust ID of the product you receive.