Coveralls and their different types of ASTM levels

Medical coverall gowns should not be confused with standard medical and surgical gowns. The primary difference between a coverall gown and a regular isolation gown is the level of protection they provide. A typical medical gown only protects the upper and lower body on the front, whereas coveralls offer almost full-body protection.

If you’re looking for personal protective equipment (PPE) suitable for high-risk medical procedures, here are the top seven features to look for in a coverall gown.

Protection Level

The protection level of medical gowns and coveralls is determined using the same standards and test procedures. ANSI/AAMI PB70:2012 tests for fluid penetration and provides four different protection level ratings:

  • AAMI Level 1: Minimal
  • AAMI Level 2: Low
  • AAMI Level 3: Moderate
  • AAMI Level 4: High

AAMI Levels 1 and 2 are suitable for most healthcare facilities and general-purpose medical environments. Levels 3 and 4 are more suitable for surgery and other heavy-duty operations with a high risk of fluid projection or exposure to bloodborne or waterborne pathogens. Therefore, a Level 4 coverall provides the highest overall protection level.

However, the higher the protection level, the denser the materials, meaning you are trading comfort for safety. Wearing high-level coveralls for prolonged periods can be uncomfortable, especially if the protection level they provide is higher than necessary for your personnel.

It is essential to conduct a risk and hazard assessment, determine which protection ratings you need the most, and acquire only the ones you are most likely to use.

Body Coverage

Unlike regular isolation and surgical gowns, coverall gowns provide 360° body protection: they cover both the front and the back of the wearer’s body using a one-piece design. However, not all gowns designated as coveralls protect the same body parts.

If you’re looking for the most effective protection level, look for the following features:

Head Protection

Verify whether the coverall comes with an integrated hood to protect the head’s top, sides, and back. A lack of integrated head protection means additional PPE is required.

Cuffs and Pant Legs

The hand and pant leg openings (at the wrist and ankles) should feature shrink cuffs to seal gaps and reinforce its protective capabilities. Shrink cuffs also grip the wearer’s gloves and fit inside medical-grade mid-calf boots, minimizing the risk of glove displacement or accidental skin exposure.

Elastic Waistband

The coverall should feature a tight-fitting elastic contraction belt or equivalent passive tightening device, allowing the user to adjust the suit to their body, improving fit and comfort without requiring an external belt. The waistband also eliminates the risks of wearing overly loose PPE, which can catch on objects, cause tears or seam failures, and compromise the coverall’s protective qualities.

Taped Zipper Closures

Zipper closures are a weak point of a coverall. Verify that they possess large storm flaps and adhesive tapes to protect clothing from exposure to contaminated fluids.

Seam Type and Protection

The seam type and design are critical to a medical coverall’s capability to repel dry particulates, fluids, and liquids. High-quality seams also improve the coverall gown’s durability, providing additional tear resistance and a degree of chemical resistance.

Coveralls for patient care may employ one of four seam types, some of which provide better protection than others:

Serged Seams

Serged seams bind two pieces of fabric with interlocking thread stitches. They are the most economical seam type but also the least protective. Serged seams are only found on low protection level gowns and coveralls, protecting against exposure to dry particulates.

Sewn and Bound Seams

Instead of directly binding two pieces of fabric, the edges are overlaid with a third piece, which is then chain-stitched together. This seam type provides better protection against dry particles than surged seams and moderate protection from liquids and fluids.

Sewn and Heat-Sealed Seams

This seam type begins with a standard stitching process, which is then reinforced with strips of heat-activated tape on the outside. This sealing method is practically liquid and fluid-proof and can provide chemical protection.

Double Heat-Sealed Seams

This seam type features an additional protection layer over standard sewn and heat-sealed seams. The heat-activated tape can be found on both the inside and the outside of the garment. This sealing method is the strongest available, providing an even higher degree of chemical resistance.

Materials and Durability

The strength of the seams is of little importance if the coverall’s primary materials don’t provide the durability you may need.

As with medical gowns and other types of PPE, most coveralls are disposable and employ synthetic polymer materials in their construction. The most durable materials are polypropylene (PP), polyethylene (PE), or SMS material.

SMS stands for spunbond-meltblown-spunbond, referencing its three-layer composition. SMS material is employed by face masks and other respiratory protective gear. Its purpose is to protect mucous membranes by keeping outside moisture and inside perspiration from passing through itself.

Specific types of medical coveralls are designated as reusable. They employ a blend of cotton and polyester, woven and chemically treated, to improve their protection against fluids and liquids while also being machine-washable. However, the protection capabilities of these gowns degrade after every wash. After a specific number of washing cycles, the manufacturer no longer guarantees the coverall’s protection rating.

Keep track of the number of washing cycles each reusable coverall has received; once they have reached their recommended maximum number of washing cycles, you should dispose of and replace them.


Coveralls are designed to be worn over street clothes and complementary PPE as defined by the Occupational Safety and Health Administration (OSHA), such as pairs of gloves, boots, a face mask or respirator, and safety goggles.

Use the sizing chart below as a reference point:

  • XS: Suitable for wearers between 5’ and 5’3”, weighing 90 to 115 lbs.
  • S/SM: Suitable for wearers between 5’ and 5’7”, weighing 100 to 125 lbs.
  • M/MD: Suitable for wearers between 5’3” and 5’7”, weighing 125 to 155 lbs.
  • L/LG: Suitable for wearers between 5’5” and 5’10”, weighing 140 to 200 lbs.
  • XL: Suitable for wearers between 5’7” and 6’2”, weighing 155 to 220 lbs.
  • 2X/XXL: Suitable for wearers between 5’11” and 6’4”, weighing 180 to 250 lbs.
  • 3X/XXL: Suitable for wearers between 6’2” and 6’6”, weighing 230 to 270 lbs.

Depending on the individual, wearing 1 or 2 sizes above the recommended size may still provide a tight and comfortable fit.

Compliance with Other Testing Protocols

Aside from liquid barrier performance testing (ANSI/AAMI PB70:2012), the Centers for Disease Control and Prevention (CDC) recommends that medical coveralls pass the following testing protocols:

  • ASTM F1670 or ISO 16603: Synthetic blood penetration test
  • ASTM F1671 or ISO 16604: Viral penetration test
  • AATCC 42 and AATCC 127: Water resistance tests (respectively: impact penetration and hydrostatic pressure)


Medical coverall gowns may be designated as sterile or non-sterile. Equipment is defined as “sterile” when it protects both the wearer from the environment and the environment from itself, such as by releasing particles, lint, and other contaminants.

A sterile coverall gown should have the following:

  • Has passed a Gelbo lint test and is certified low-linting
  • Has passed an ASTM D4966 abrasion resistance test