How to Measure Air Permeability of Nonwoven Materials: Testing Methods, Standards & Buyer Guide

Introduction: Why Air Permeability Matters in Nonwoven Material Selection

When purchasing nonwoven materials, many buyers focus on visible specifications such as:

• GSM (fabric weight)

• thickness

• color

• width

• price

However, one of the most important technical properties that directly affects product performance is often overlooked:

air permeability.

Air permeability determines how easily air can pass through the internal structure of a nonwoven material.

It directly influences:

• breathability

• wearer comfort

• moisture management

• filtration performance

• product usability

For industries such as medical protection, agriculture, hygiene, and filtration, selecting the correct air permeability level is critical.

A material with insufficient air permeability may cause:

• poor ventilation

• uncomfortable wearing experience

• excessive heat accumulation

• reduced application performance

However, excessively high air permeability may reduce:

• barrier performance

• liquid resistance

• filtration efficiency

Therefore, professional buyers need to understand:

How air permeability is measured, what standards are used, and how to select the correct value for different applications.

1. What Is Air Permeability of Nonwoven Materials?

Definition of Air Permeability

Air permeability refers to the ability of a nonwoven material to allow air to pass through its structure under a specified pressure difference.

In simple terms:

It measures how easily air can flow through the fabric.

A material with high air permeability allows more air movement.

A material with low air permeability restricts airflow.

Why Nonwoven Structure Affects Airflow

Unlike woven fabrics, nonwoven materials are created by bonding fibers together.

Their internal structure contains:

• fiber networks

• pores

• air channels

• bonding points

The size and distribution of these spaces determine how easily air can pass through.

Basic Relationship:

Larger pores:

↓

more airflow

↓

higher air permeability

Smaller pores:

↓

less airflow

↓

lower air permeability

2. Common Units Used for Air Permeability Measurement

Different markets and laboratories use different measurement units.

The most common units include:

• L/m²/s

• CFM

• mm/s

Air Permeability Units Comparison

Why Unit Conversion Matters for Buyers

When comparing suppliers from different countries, buyers should confirm:

• testing standard

• testing pressure

• measurement unit

Otherwise, different values may not be directly comparable.

Example:

Supplier A:

500 L/m²/s

Supplier B:

100 CFM

These numbers cannot be compared directly without conversion.

3. Why Air Permeability Is Important for Nonwoven Applications

Air permeability is not just a laboratory value.

It directly affects real-world product performance.

Application 1: Medical Nonwoven Materials

Medical products require a balance between:

• protection

• breathability

• comfort

Applications include:

• surgical gowns

• isolation gowns

• protective clothing

• medical packaging

Why Breathability Matters

Healthcare workers may wear protective clothing for many hours.

Poor air permeability can cause:

• heat buildup

• discomfort

• moisture accumulation

However:

Excessive air permeability may reduce:

• barrier protection

• liquid resistance

Therefore:

Medical materials require optimized airflow rather than maximum airflow.

Application 2: Agricultural Nonwoven Fabrics

Agricultural applications include:

• crop protection covers

• frost protection fabrics

• greenhouse materials

Plants require:

• air exchange

• moisture balance

• temperature regulation

A suitable air permeability level helps:

• reduce excessive humidity

• improve plant growth conditions

• maintain a stable micro-environment

Application 3: Hygiene Products

Spunbond nonwoven materials are widely used in:

• diapers

• sanitary products

• personal care products

Air permeability affects:

• softness

• skin comfort

• moisture control

A breathable structure improves user experience.

Application 4: Filtration Materials

Filtration applications require a careful balance.

Air must pass through the material, but particles must be captured.

Higher airflow:

Advantages:

• lower pressure drop

• easier air movement

Disadvantages:

• possible reduction in filtration efficiency

Lower airflow:

Advantages:

• better particle capture potential

Disadvantages:

• increased resistance

Application and Air Permeability Requirements

4. How Is Air Permeability Measured?

Air permeability is measured using a specialized instrument called an:

Air Permeability Tester

The equipment measures the amount of air passing through a fixed fabric area under controlled pressure conditions.

Basic Testing Principle

The testing process follows:

Sample

↓

Controlled pressure difference

↓

Airflow passes through material

↓

Equipment measures airflow

↓

Air permeability value is calculated

Air Permeability Testing Process

Step 1: Sample Preparation

The test sample is prepared according to the selected standard.

Important factors include:

• sample size

• fabric condition

• environmental conditions

Step 2: Sample Installation

The nonwoven sample is placed and sealed on the testing area.

The sealing prevents air leakage around the edges.

Step 3: Apply Pressure Difference

The instrument creates a controlled pressure difference between both sides of the material.

This forces air through the fabric structure.

Step 4: Measure Airflow

The equipment records:

• airflow volume

• pressure difference

• permeability value

Step 5: Record Test Results

The final result is usually expressed as:

• L/m²/s

• CFM

• mm/s

Air Permeability Testing Steps

5. International Air Permeability Testing Standards

Professional manufacturers usually follow recognized testing standards.

The most common standards include:

ASTM D737

Standard Test Method for Air Permeability of Textile Fabrics

Widely used in:

• North America

• textile industries

• nonwoven testing

It measures:

• airflow through fabric

• under a specified pressure difference

ISO 9237

Determination of Permeability of Textile Fabrics to Air

Commonly used internationally.

It evaluates:

• air flow rate

• fabric permeability

EN Standards

European markets may refer to EN testing requirements depending on product category.

Testing Standard Comparison

6. Factors Affecting Air Permeability of Nonwoven Materials

Air permeability is determined by the complete material structure.

The main influencing factors include:

Factor 1: Fiber Diameter

Fiber diameter has a direct impact on pore structure.

Larger Fiber Diameter

Generally creates:

• larger spaces between fibers

• more open structure

• higher airflow

Smaller Fiber Diameter

Generally creates:

• denser fiber network

• smaller pores

• lower airflow

Fiber Diameter vs Air Permeability

Example:

Spunbond fabric:

• larger continuous filaments

• open structure

Usually:

higher air permeability

Meltblown fabric:

• microfiber structure

• dense network

Usually:

lower air permeability

Factor 2: GSM (Fabric Weight)

GSM affects fabric density.

Generally:

Higher GSM:

↓

more fibers per area

↓

denser structure

↓

lower airflow

However:

GSM alone cannot determine air permeability.

Two fabrics with the same GSM can have different airflow because of:

• fiber diameter

• bonding conditions

• production technology

Factor 3: Fiber Bonding

Bonding points affect airflow channels.

During thermal bonding:

• fibers are connected

• pore structure changes

Excessive bonding:

may reduce airflow.

Insufficient bonding:

may create unstable structure.

Factor 4: Fabric Thickness

Thicker materials usually create:

• longer airflow paths

• higher resistance

Therefore:

thickness can influence permeability.

Factor 5: Raw Material and Additives

Different materials influence:

• fiber formation

• surface structure

• pore distribution

For PP spunbond fabrics:

polypropylene quality affects final airflow characteristics.

Air Permeability Performance Analysis of Different Nonwoven Materials

In Part 1, we explained the definition of air permeability, testing principles, international standards, and the main factors affecting airflow performance.

For buyers, however, the most important question is:

“What air permeability level is suitable for my application?”

The answer depends on:

• material structure

• fiber diameter

• GSM

• application requirements

• required balance between breathability and protection

A professional buyer should not simply choose the highest air permeability material.

The correct choice is:

The material that provides the right airflow performance while meeting strength, barrier, and durability requirements.

7. Air Permeability Comparison: Spunbond vs Meltblown vs SMS

Different nonwoven technologies create different fiber structures.

This directly affects air permeability.

7.1 Spunbond Nonwoven Fabric Air Permeability

Spunbond fabric is produced by:

• extruding polypropylene polymer

• forming continuous filaments

• stretching fibers

• bonding fibers through heat

Structural Characteristics

Spunbond has:

• continuous fibers

• relatively larger fiber diameter

• open pore structure

Because of this structure:

Spunbond generally provides:

• good breathability

• high air permeability

• good mechanical strength

Typical Applications

• agricultural covers

• shopping bags

• medical gowns

• hygiene products

7.2 Meltblown Nonwoven Fabric Air Permeability

Meltblown fabric uses:

• extremely fine fibers

• high-speed hot air drawing

• dense microfiber network

Structural Characteristics

Meltblown contains:

• very small fiber diameter

• high fiber density

• smaller pores

Therefore:

It usually has:

• lower air permeability

• higher filtration capability

Typical Applications

• face mask filtration layers

• air filtration

• liquid barrier materials

7.3 SMS Nonwoven Fabric Air Permeability

SMS means:

Spunbond + Meltblown + Spunbond

Structure:

Spunbond
    ↓
Meltblown
    ↓
Spunbond

SMS combines:

Outer layers:

• strength

• durability

Middle layer:

• filtration

• barrier performance

Air Permeability Comparison Table

8. Relationship Between Air Permeability and Filtration Efficiency

One of the biggest misunderstandings among buyers is:

“Higher air permeability always means better fabric.”

This is incorrect.

Performance depends on application.

For example:

A medical mask requires:

• sufficient airflow

• high particle filtration

If airflow is too high:

• air resistance decreases

• filtration efficiency may reduce

If airflow is too low:

• breathing becomes difficult

The Balance Between Airflow and Filtration

Professional manufacturers optimize:

fiber diameter + pore structure + material layers

to achieve balance.

9. Air Permeability and Breathability Performance

Breathability is one of the most important reasons buyers evaluate air permeability.

What Is Breathability?

Breathability refers to how easily:

• air

• heat

• moisture vapor

can move through a material.

Higher air permeability usually improves:

• comfort

• ventilation

• moisture release

Applications requiring high breathability:

• protective clothing

• agricultural covers

• hygiene materials

Example:

A worker wearing protective clothing for 8 hours requires:

Protection:

Breathability

A material with excellent barrier properties but extremely low airflow may cause:

• heat buildup

• discomfort

• reduced usability

10. Typical Air Permeability Requirements by Application

There is no universal “best” air permeability value.

The correct value depends on the final product.

Application-Based Selection Guide

11. How Buyers Should Evaluate Air Permeability Test Reports

A professional buyer should understand what information matters in a test report.

Important Test Report Information

1. Material Information

Should include:

• material type

• GSM

• thickness

• production batch

2. Testing Standard

Confirm:

• ASTM D737?

• ISO 9237?

• Other standards?

3. Pressure Difference

Air permeability values depend on testing pressure.

Different pressure conditions may produce different results.

4. Testing Direction

Some materials may have slightly different performance depending on:

• machine direction

• cross direction

Test Report Checklist

12. How Manufacturers Control Air Permeability During Production

Reliable manufacturers control air permeability through multiple production parameters.

12.1 Controlling Fiber Diameter

Fiber diameter affects:

• pore size

• airflow channels

• material density

Manufacturers adjust:

• extrusion conditions

• drawing speed

• polymer characteristics

12.2 Controlling GSM

Changing GSM changes:

• fiber quantity

• material density

Higher GSM usually creates:

• thicker structure

• lower airflow

12.3 Controlling Bonding Temperature

Thermal bonding affects:

• fiber connection points

• pore structure

Too much bonding:

↓

fewer open spaces

↓

lower air permeability

Too little bonding:

↓

unstable structure

↓

quality problems

12.4 Controlling Raw Material Quality

Polypropylene quality affects:

• filament formation

• fiber uniformity

• final fabric structure

Production Factors Affecting Air Permeability

13. Common Buyer Mistakes When Evaluating Air Permeability

Mistake 1: Choosing the Highest Air Permeability

Higher is not always better.

Example:

Agriculture:

High airflow is beneficial.

Filtration:

Too much airflow may reduce performance.

Mistake 2: Comparing Values Without Checking Standards

Example:

Supplier A:

500 L/m²/s

Supplier B:

100 CFM

Without knowing:

• standard

• pressure

• conversion

comparison may be inaccurate.

Mistake 3: Ignoring Other Performance Parameters

Air permeability should be evaluated together with:

• tensile strength

• hydrostatic pressure

• filtration efficiency

• GSM

Mistake 4: Focusing Only on Price

A cheaper fabric may have:

• inconsistent airflow

• unstable quality

• poor application performance

14. How to Select a Reliable Nonwoven Supplier Based on Air Permeability

A professional supplier should provide more than a quotation.

They should provide:

• technical support

• testing data

• application recommendations

Supplier Evaluation Checklist

Questions Buyers Should Ask Suppliers

Before ordering:

Question 1:

What testing standard is used for air permeability?

Question 2:

Can you provide test results with GSM information?

Question 3:

Can air permeability be customized?

Question 4:

How do you maintain consistency between batches?

Question 5:

Can you recommend suitable fabric structure for my application?

15. Relationship Between Air Permeability and Other Fabric Properties

Air permeability does not work independently.

It interacts with:

• tensile strength

• fiber diameter

• GSM

• thickness

• filtration

Performance Relationship Table

16. Practical Example: Choosing Fabric for Different Applications

Example 1: Agricultural Crop Cover

Buyer requirement:

• protect crops

• allow air exchange

• control moisture

Recommended focus:

✓ higher air permeability
✓ suitable GSM
✓ UV resistance

Example 2: Medical Protective Gown

Buyer requirement:

• protection

• comfort

• long wearing time

Recommended focus:

✓ balanced air permeability
✓ tensile strength
✓ liquid resistance

Example 3: Filtration Material

Buyer requirement:

• particle capture

• controlled airflow

Recommended focus:

✓ filtration efficiency
✓ pressure drop
✓ airflow balance