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What Is Air Permeability in Spunbond Nonwoven Fabric?

Spunbond nonwoven air permeability describes how easily air can pass through a spunbond fabric under a specified pressure difference.

It is an important performance characteristic for applications where the fabric needs to allow air exchange rather than act as a completely closed barrier.

Depending on the application, air permeability can affect:

• Ventilation

• Moisture transport

• Breathability

• Drying behavior

• Temperature regulation

• Pressure equalization

• Filtration performance

• Crop microclimate

• Comfort

• Dust and particle behavior

For buyers, however, "high air permeability" is not automatically better.

A fabric used for agricultural protection may need substantial airflow, while another application may require lower permeability to improve protection or containment.

The correct target is therefore:

The appropriate air permeability for the intended application.

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1. What Does Air Permeability Measure?

Air permeability measures the volume of air passing through a known area of fabric under a specified pressure difference during a specified period.

A simplified relationship is:

Air permeability = Airflow rate ÷ Test area

The reported value depends on the selected testing method.

Common units can include:

• L/m²/s

• m³/m²/min

• ft³/ft²/min

• mm/s

Because different standards can use different pressure differences and reporting units, two air-permeability numbers should not be compared directly without checking the test conditions.

For procurement purposes, the complete specification should identify:

• Test standard

• Test pressure

• Test area

• Test direction, where relevant

• Reporting unit

• Conditioning conditions

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2. Why Air Permeability Matters in Spunbond Fabric

A spunbond nonwoven fabric is not a solid plastic film.

It consists of a network of continuous filaments bonded together.

Spaces between the filaments create pathways through which air can travel.

The structure therefore affects:

Airflow → ventilation → moisture movement → application performance

This makes air permeability particularly important for applications such as:

• Agricultural covers

• Horticultural materials

• Mattress components

• Furniture materials

• Hygiene products

• Medical materials

• Protective covers

• Packaging components

• Filtration support layers

• Building and industrial materials

The required permeability varies significantly between applications.

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3. Is Spunbond Nonwoven Fabric Breathable?

In many applications, yes.

Spunbond nonwoven fabrics generally contain interconnected pores that allow air to pass through the structure.

However, "breathable" is a broad description.

A technical buyer should ask for a measurable air-permeability value rather than simply accepting a supplier's statement that the fabric is breathable.

For example:

Instead of:

"This 30 GSM fabric has good breathability."

Ask:

"What is the measured air permeability, under which test standard and pressure?"

This converts a subjective description into a measurable technical specification.

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4. How Is Spunbond Nonwoven Air Permeability Measured?

An air permeability test for nonwoven fabric generally works by creating a controlled pressure difference across a specimen.

The basic process is:

Fabric specimen → controlled pressure difference → air passes through fabric → airflow is measured

The testing instrument typically includes:

• Airflow measurement system

• Test head or test area

• Pressure-control system

• Clamping mechanism

• Data display

The specimen is placed over the test opening and securely clamped.

Air is then forced through the fabric under the specified test pressure.

The instrument measures the resulting airflow.

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5. Step-by-Step Air Permeability Testing

Step 1: Prepare the Sample

The fabric sample should be representative of the production batch.

Avoid areas containing:

• Visible holes

• Wrinkles

• Contamination

• Edge damage

• Unusual bonding defects

unless the purpose of the test is specifically to evaluate defects.

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Step 2: Condition the Fabric

Where required by the test method, condition the specimen under controlled temperature and humidity.

This helps make results more repeatable.

Environmental conditions can affect textile and nonwoven testing, so the same conditioning procedure should be used when comparing different suppliers.

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Step 3: Place the Specimen on the Test Head

The specimen is placed flat over the test opening.

The test area should be known and controlled.

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Step 4: Clamp the Fabric

The specimen must be securely held to prevent air leakage around the edges.

Edge leakage can create an artificially high measured airflow.

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Step 5: Apply the Specified Pressure Difference

The testing instrument establishes the pressure difference required by the selected test method.

This is a critical part of the measurement.

A result obtained at one pressure difference should not automatically be compared with a result obtained at another.

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Step 6: Measure Airflow

The instrument measures the amount of air passing through the fabric.

The result is then converted into the reporting unit required by the test method.

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Step 7: Repeat the Measurement

Multiple measurements should normally be performed at different locations.

The average result can then be calculated according to the relevant test procedure.

This helps identify fabric uniformity.

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6. Why Test Pressure Matters

Air permeability is not simply one fixed number independent of testing conditions.

The pressure difference applied during the test affects the measured airflow.

Imagine two reports:

Fabric A: 500 L/m²/s at one specified pressure

Fabric B: 550 L/m²/s at a different pressure

It would be incorrect to conclude automatically that Fabric B is more permeable.

The testing pressure may be different.

Therefore, when comparing suppliers, always check:

Value + unit + pressure + test method

rather than the numerical value alone.

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7. Common Units for Air Permeability

Air permeability can be reported in several units.

Examples include:

Unit	General Meaning
L/m²/s	Liters of air per square meter per second
m³/m²/min	Cubic meters per square meter per minute
ft³/ft²/min	Cubic feet per square foot per minute
mm/s	Air velocity through the specimen

A buyer should not compare the numbers directly unless the units and test conditions have been normalized.

This is particularly important when comparing test reports from factories in different countries.

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8. What Determines Spunbond Fabric Air Permeability?

Several structural variables influence spunbond fabric air permeability.

The most important include:

GSM

Higher GSM generally means more material per unit area.

Thickness

A thicker structure can increase the path length through the fabric.

Filament Diameter

Smaller or larger filaments can alter pore structure.

Web Density

The amount and distribution of filaments influence the available airflow pathways.

Bonding

Thermal bonding changes the structure of the web.

Calender Pressure

Higher compression can reduce void spaces.

Fiber Orientation

The arrangement of filaments affects pore geometry.

Surface Treatments

Hydrophilic, hydrophobic or other treatments can alter surface characteristics and sometimes affect airflow.

Therefore:

Air permeability is a structural property, not simply a GSM property.

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9. GSM vs Air Permeability

This is one of the most important relationships for buyers.

In many spunbond constructions:

Higher GSM → more material → potentially lower air permeability

But this is not a universal linear relationship.

Consider an illustrative example:

GSM	Example Air Permeability
15 GSM	High
20 GSM	High
30 GSM	Medium-high
40 GSM	Medium
50 GSM	Lower

The exact values depend on the fabric construction and test conditions.

A manufacturer can potentially produce two fabrics with the same GSM but different air permeability by changing:

• Filament structure

• Web density

• Bonding

• Calendering

• Production parameters

Therefore, GSM should not be used as a substitute for an actual air-permeability measurement.

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10. Does Higher GSM Always Reduce Air Permeability?

No.

The general tendency may be for heavier structures to provide greater resistance to airflow, but the relationship is influenced by the entire pore structure.

For example:

30 GSM Fabric A

may have higher air permeability than:

30 GSM Fabric B

because Fabric A has a more open structure.

Similarly, a carefully engineered 40 GSM fabric may have acceptable airflow for an application even though it is heavier than a 30 GSM product.

The correct approach is to specify the required air-permeability range and then select an appropriate GSM and construction.

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11. How Thickness Affects Airflow

Thickness can affect the path that air travels through the fabric.

A thicker nonwoven structure can provide a longer and more complex airflow path.

But thickness must be considered together with:

• Density

• Porosity

• Filament diameter

• Bonding

• Compression

This means:

Thickness ≠ Air permeability

A thick fabric can still have relatively high permeability if its internal structure contains sufficiently open pathways.

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12. Porosity and Air Permeability

Porosity refers broadly to the amount and characteristics of open space within a material.

Spunbond fabric contains spaces between filaments.

These spaces form interconnected pathways through which air can travel.

When the structure becomes:

• More open → airflow can increase

• More compact → airflow can decrease

However, measured air permeability is influenced by more than total void volume.

The:

• Size

• Distribution

• Shape

• Connectivity

of the pores also matter.

This is why two fabrics with similar GSM and thickness can have different air-permeability results.

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13. Air Permeability vs Breathability

These terms are related but should not be treated as identical.

Air Permeability

A measurable property describing airflow through a fabric under specified test conditions.

Breathability

A broader functional concept that can include:

• Air exchange

• Moisture transport

• Water-vapor behavior

• Comfort

• Thermal regulation

For technical procurement, air permeability provides a more objective parameter.

If the application depends on ventilation, buyers should specify a measurable air-permeability requirement rather than simply saying:

"Breathable nonwoven."

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14. Air Permeability in Agricultural Spunbond Fabric

Agriculture is one of the clearest applications where air permeability matters.

Agricultural spunbond materials may be used for:

• Crop covers

• Frost protection

• Insect protection

• Nursery covers

• Plant growth protection

• Weed-control systems

• Horticultural applications

The fabric needs to provide a suitable balance between:

Protection + airflow + light transmission + moisture behavior

If airflow is too restricted, the microenvironment around the crop can change.

If airflow is too high, the fabric may not provide the desired protection function.

Therefore, air permeability should be evaluated alongside:

• GSM

• Thickness

• UV stabilization

• Light transmission

• Water behavior

• Tensile strength

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15. Air Permeability in Mattress and Furniture Materials

Mattress and furniture manufacturers may also use spunbond nonwoven materials in different internal or external components.

Air permeability can influence:

• Ventilation

• Moisture movement

• Comfort

• Drying

• Internal airflow

But the required value depends on the layer's function.

A structural backing layer does not necessarily need the same air permeability as a comfort-related component.

This is why buyers should define the function of the fabric before specifying the permeability.

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16. Air Permeability in Medical and Hygiene Applications

Air permeability can be important in:

• Disposable hygiene products

• Medical nonwoven structures

• Protective garments

• Back sheets

• Certain breathable components

However, these applications often require balancing airflow with other properties such as:

• Liquid resistance

• Water-vapor transmission

• Barrier performance

• Tensile strength

• Softness

• Cleanliness

A highly air-permeable fabric is not necessarily suitable if the application requires a liquid barrier.

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17. Air Permeability and Hydrophobic Spunbond Fabric

Hydrophobic treatment and air permeability address different properties.

A hydrophobic fabric is designed to resist wetting by liquid water.

Air permeability describes the movement of air through the fabric.

Therefore:

Hydrophobic ≠ airtight

and:

Air-permeable ≠ water-permeable

A spunbond fabric can be:

• Air permeable

• Hydrophobic

• Resistant to liquid water under certain conditions

at the same time.

This distinction is important when selecting agricultural, medical, packaging or protective materials.

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18. Air Permeability vs Water Resistance

This is another common procurement misunderstanding.

Buyers sometimes assume:

"If air can pass through, water must also pass through."

Not necessarily.

The interaction between a fabric and liquid water depends on:

• Surface energy

• Fiber structure

• Pore size

• Water pressure

• Surface treatment

• Liquid properties

Air and liquid water behave differently when moving through a nonwoven structure.

Therefore, air permeability should be specified separately from:

• Hydrostatic pressure

• Water repellency

• Spray resistance

• Water penetration

depending on the application.

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19. Air Permeability and Filtration

Air permeability is particularly important in filtration-related applications, but it should not be confused with filtration efficiency.

A fabric can allow substantial airflow while still providing useful filtration performance.

Filtration depends on additional factors such as:

• Fiber diameter

• Pore structure

• Electrostatic effects

• Thickness

• Layer structure

• Particle size

• Test conditions

Therefore:

High air permeability does not automatically mean high filtration efficiency.

For filtration applications, both airflow resistance and filtration performance should be evaluated.

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20. How Bonding Affects Air Permeability

Thermal bonding creates points where the spunbond filaments are joined.

Bonding conditions can influence:

• Pore structure

• Surface compactness

• Thickness

• Stiffness

• Mechanical strength

• Airflow

If the web becomes excessively compressed, the open spaces available for airflow may decrease.

This can reduce air permeability.

However, bonding must also provide sufficient mechanical integrity.

The manufacturer therefore needs to balance:

Strength ↔ bonding ↔ flexibility ↔ permeability

rather than maximizing any single property.

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21. How Calendering Affects Air Permeability

Calendering applies heat and pressure to the web.

It can influence:

• Bonding

• Thickness

• Surface structure

• Stiffness

• Pore structure

• Air permeability

Increasing compression can make the fabric denser.

This may reduce the pathways available for airflow.

But the final effect depends on the exact process conditions and bonding pattern.

Therefore, a buyer should evaluate actual test results rather than assuming a specific calender setting will produce a universal permeability value.

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22. Air Permeability and Fabric Uniformity

Uniformity matters because airflow can vary across the width of a roll.

Suppose one area contains:

• More filaments

• Higher density

• Stronger bonding

while another area is more open.

The measured air permeability may vary between locations.

This can be important in:

• High-speed converting

• Filtration

• Medical materials

• Agricultural fabrics

• Automated manufacturing

For quality control, multiple measurement locations are therefore more useful than a single measurement.

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23. How Buyers Should Read an Air Permeability Test Report

A useful report should identify:

Parameter	Example
Product	PP Spunbond
GSM	30 g/m²
Test Method	Specified standard
Test Pressure	Specified
Test Area	Specified
Unit	L/m²/s
Measurement 1	Recorded
Measurement 2	Recorded
Measurement 3	Recorded
Average	Calculated
Sample Location	Recorded
Test Date	Recorded

Without the test conditions, the numerical result has limited value for supplier comparison.

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24. Why Different Suppliers Can Report Different Air Permeability

Suppose two suppliers both quote:

30 GSM PP spunbond

Supplier A reports:

600 L/m²/s

Supplier B reports:

450 L/m²/s

This does not automatically mean Supplier A is better.

First verify:

• Same test standard?

• Same test pressure?

• Same unit?

• Same test area?

• Same conditioning?

• Same GSM tolerance?

• Same fabric treatment?

• Same production structure?

If the conditions are different, the numbers may not be directly comparable.

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25. Air Permeability and GSM: A Practical Example

Suppose a buyer needs a breathable agricultural fabric.

Three options are offered:

Fabric	GSM	Air Permeability	UV	Tensile
A	17	High	Yes	Moderate
B	25	Medium-high	Yes	Higher
C	35	Medium	Yes	High

If the crop protection application requires:

• Good airflow

• Moderate strength

• UV stability

Fabric B may provide a better balance than simply choosing Fabric C because it has the highest tensile strength.

This is the central idea of technical fabric selection:

Choose the combination of properties that matches the application.

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26. How to Select Air Permeability for Different Applications

There is no single air-permeability value suitable for every spunbond application.

A practical selection process is:

Step 1: Identify the function

Is the fabric designed for ventilation, protection, filtration, comfort or structural support?

Step 2: Determine the required airflow

How much air exchange is actually needed?

Step 3: Identify competing requirements

Does the fabric also need:

• High tensile strength?

• Water resistance?

• UV resistance?

• Low cost?

• Softness?

• High opacity?

Step 4: Establish a measurable specification

Define the target air-permeability range under an agreed test method.

Step 5: Test the production sample

Do not rely solely on the supplier's generic catalog specification.

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27. Should Buyers Specify a Minimum or a Range?

It depends on the application.

For some applications, a minimum air permeability may be appropriate.

For others, both upper and lower limits may be useful.

For example:

Air permeability: X–Y L/m²/s under specified conditions

A range can help control production consistency.

If the permeability is too high or too low, the material may not perform as expected.

The appropriate acceptance range should therefore be established from application testing.

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28. Air Permeability and Cost

Air permeability is not normally a direct pricing parameter in the same way that GSM is.

However, changing the fabric structure to achieve a particular permeability can affect production economics.

For example, achieving a more open structure may involve changes to:

• GSM

• Filament characteristics

• Web formation

• Bonding

• Production speed

These changes can influence the final cost.

Therefore, buyers should not simply specify:

"Maximum air permeability at minimum price."

The target should be technically realistic and commercially practical.

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29. How to Avoid Over-Specifying Air Permeability

Suppose an agricultural buyer requires:

Minimum air permeability = X

The supplier offers a fabric with permeability far above the required level.

Does that automatically mean better performance?

No.

Excessively high airflow could potentially reduce the protective effect required by the application.

The goal should be:

Required airflow, not maximum airflow.

This principle is similar to GSM and tensile strength.

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30. Air Permeability vs Other Spunbond Properties

Air permeability should be evaluated as part of a larger property system.

Property	Main Function
GSM	Material weight
Thickness	Physical structure
Tensile strength	Resistance to pulling
Elongation	Stretch behavior
Air permeability	Airflow
Water resistance	Liquid protection
UV resistance	Outdoor durability
Tear strength	Resistance to tear propagation
Opacity	Visual coverage

A fabric is suitable only when the combination of properties matches the application.

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31. Common Mistakes When Evaluating Air Permeability

Mistake 1: Assuming higher is always better

It depends on the application.

Mistake 2: Comparing numbers without checking test pressure

Different pressure conditions can produce different results.

Mistake 3: Ignoring GSM

GSM influences the fabric structure and should be evaluated alongside permeability.

Mistake 4: Confusing air permeability with breathability

Breathability is a broader functional concept.

Mistake 5: Confusing air permeability with waterproofness

Airflow and liquid resistance are different properties.

Mistake 6: Testing only one location

A single measurement may not represent the whole roll.

Mistake 7: Comparing different units directly

Always normalize the units before comparison.

Mistake 8: Specifying only "good breathability"

Use measurable technical requirements.

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32. A Practical Supplier Comparison Example

Suppose two suppliers offer similar material:

Parameter	Supplier A	Supplier B
GSM	30	30
Air permeability	580	470
MD tensile	78 N	85 N
CD tensile	45 N	50 N
Price/kg	$1.18	$1.21

Which is better?

There is no universal answer.

If the application prioritizes airflow, Supplier A may be more attractive.

If the application prioritizes mechanical strength, Supplier B may be preferable.

If both meet the minimum requirements, price and consistency become additional decision factors.

This is why procurement should start with application requirements, not supplier specifications.

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33. How Air Permeability Can Change During Converting

The measured permeability of the original roll may not equal the permeability of the final product.

Converting processes can include:

• Lamination

• Coating

• Heat sealing

• Printing

• Compression

• Needle punching

• Folding

• Multiple-layer assembly

These processes can change the final airflow characteristics.

Therefore, when air permeability is critical, test the final material configuration, not only the base fabric.

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34. How to Write an RFQ for Air-Permeable Spunbond Fabric

Instead of:

"Please quote breathable spunbond fabric."

Use a specification such as:

Material: PP spunbond nonwoven fabric
GSM: 30 g/m²
Width: 1.6 m
Color: White
Air permeability: Agreed target/range
Test method: Agreed standard
Test pressure: Specified
MD tensile: Minimum requirement
CD tensile: Minimum requirement
UV: Required if used outdoors
Treatment: Hydrophobic/hydrophilic as required
Roll length: Specified

This gives the supplier a measurable target and makes quotations easier to compare.

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35. FAQ: Spunbond Nonwoven Air Permeability

What is spunbond nonwoven air permeability?

It is the amount of air that can pass through a specified area of spunbond fabric under a specified pressure difference and test condition.

Is higher air permeability better?

Not always. The ideal value depends on the application. Agricultural covers, filtration materials and protective fabrics can have very different permeability requirements.

Does higher GSM reduce air permeability?

Often, increasing GSM can reduce airflow because more material is present within the fabric structure, but the relationship is not universal. Filament diameter, web density and bonding also matter.

How is air permeability tested?

A controlled pressure difference is applied across a fabric specimen, and the airflow passing through the specimen is measured according to a specified test method.

Why do two suppliers give different air-permeability values for the same GSM?

Because the fabrics may have different filament structures, web density, bonding, thickness or treatments. The test conditions may also be different.

Is air permeability the same as breathability?

No. Air permeability is a measurable airflow property. Breathability is a broader concept that can include air exchange, moisture transport and comfort.

Is air-permeable spunbond waterproof?

Not necessarily. Air permeability and liquid-water resistance are separate properties. A fabric can allow air to pass while also having hydrophobic treatment that resists liquid water.

What unit is used for air permeability?

Common units include L/m²/s, m³/m²/min, ft³/ft²/min and mm/s. The test method should always be checked before comparing values.

Does thickness affect air permeability?

Yes, thickness can affect airflow resistance, but thickness alone does not determine permeability. The internal pore structure and density are also important.

Should air permeability be tested in every production batch?

For applications where airflow is critical, regular testing can help verify production consistency. The appropriate sampling frequency depends on the quality agreement and application risk.

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36. Final Takeaway

Spunbond nonwoven air permeability is an important technical property whenever airflow through the fabric affects product performance.

It is influenced by:

GSM + thickness + filament diameter + web density + bonding + pore structure + treatments

This is why buyers should not select air-permeable spunbond fabric simply by asking for a particular GSM.

A better specification combines:

GSM + air permeability + tensile strength + thickness + application-specific properties

When comparing suppliers, always check:

1. Air-permeability value

2. Test method

3. Test pressure

4. Reporting unit

5. Test area

6. Conditioning

7. Sample location

8. Number of measurements

Most importantly, remember that higher air permeability is not automatically better.

The correct target is the permeability that provides the required airflow while maintaining the other properties the application needs.

For B2B procurement, the most reliable approach is therefore:

Define the application → establish the required airflow → specify a measurable permeability range → test samples → verify bulk-production consistency.

That approach prevents buyers from selecting fabric based on vague terms such as "breathable" and creates a technical specification that suppliers can actually reproduce.