From Testing to Protection: Applying Penetration and Permeation Data in the Real-World

How testing methods and real-world conditions influence protective apparel performance.

• By Kevin Endres, Ph.D., Khyati Vyas, Mark Tartaglia
• Oct 15, 2026

Understanding Barrier Performance in Protective Apparel

Selecting appropriate protective apparel for chemical and biohazard applications requires a clear understanding of how hazardous substances interact with materials. Two critical concepts—penetration and permeation—are often discussed together but represent fundamentally different mechanisms of exposure. These mechanisms highlight critical aspects of chemical protection in addition to other real-world factors.

Penetration vs. Permeation

Penetration refers to the movement of liquids, solids, or microorganisms through imperfections in a material system. These pathways may include pores, seams, pinholes, zipper interfaces, or other garment construction features. Penetration is typically visible or detectable as a bulk flow through gaps or defects.

Permeation, by contrast, is a molecular process. It occurs when a chemical is absorbed into a material, diffuses through it, and then desorbs on the opposite side. This process may happen even when the material appears intact and without visible defects or openings/ gaps.

Penetration Testing: Evaluating Garment Integrity

Penetration testing focuses on identifying whether a substance can pass through a barrier material system via flaws or interfaces.

Penetration testing is most appropriate in scenarios involving:

• Non-hazardous liquid exposure
• Slurries – mixture of solid and non-hazardous liquid
• Particulate or solid contaminants
• Biological agents

It is important to note that even if the base fabric doesn’t have defects or inconsistencies failure modes may occur at seams and stitched areas, zippers and closures, and garment interfaces. Exposure conditions also play a role. Penetration risk increases with higher pressure, prolonged contact, and liquid pooling. Directionality like spraying versus immersion can significantly impact outcomes.

For biohazard protection, industry testing standards such as ASTM F1670 (synthetic blood penetration) and ASTM F1671 (viral penetration) are commonly used to assess barrier performance against bloodborne pathogens.

Penetration testing is therefore best suited for applications where exposure to non-hazardous liquids is intermittent or localized and where physical ingress is the primary concern, but permeation testing allows for an accurate evaluation of specific material hazard transfer through a protective barrier over time.

Permeation Testing: Measuring Molecular Transfer Over Time

Permeation testing evaluates how chemicals migrate through materials at the molecular level. Unlike penetration, permeation can occur without visible signs and is influenced by both material properties, chemical characteristics and environmental conditions.

Permeation is typically measured in terms of normalized breakthrough time. It is defined as the elapsed time between initial contact of the chemical with the outside surface of the material and the time at which the chemical is detected at the inside surface of the material at a permeation rate of 0.1 µg/cm2/min (typically used in North America according to ASTM F739) or 1.0 µg/cm2/min (typically used in Europe/EMEA according to EN ISO 6529). In addition, EN ISO 6529 puts greater emphasis on cumulative permeation—the total amount of chemical passing through over time. These differences can influence how performance is reported and compared across standards.

Permeation testing is especially relevant for scenarios involving:

• Continuous chemical contact, splashes, spray, and immersion
• Exposure to hazardous gases, vapors, and liquids.
• Exposure to toxic industrial chemicals (TIC) and chemical warfare agents (CWA)
• Extended-duration tasks where chemical contact may occur for prolonged periods
• Handling concentrated chemicals such as solvents, acids, or caustics
• Exposure to chemical mixtures or formulations containing multiple ingredients

In addition to the hazard scenario, understanding whether chemical exposure is continuous or intermittent is critical when evaluating permeation risk and selecting appropriate protective apparel. Intermittent contact refers to chemical exposure that occurs periodically or at repeated intervals, such as occasional splashes or brief contact events. Continuous contact occurs when a chemical remains in sustained contact with the material for an extended period, such as during immersion, prolonged handling, or frequent heavy-splash conditions. Even short exposures can become critical if repeated over time, making it important to consider cumulative effects rather than single events.

Key factors to be considered during hazard assessment that affect permeation include:

• Chemical properties: molecular size, weight, and polarity
• Concentration and mixtures: higher concentrations and complex formulations can accelerate permeation
• Temperature: elevated temperatures generally increase diffusion rates
• Contact conditions: continuous exposure increases cumulative transport
• Material characteristics: composition and barrier technology

Permeation testing is conducted using both in-house and third-party labs to evaluate material chemical barrier performance. While in-house testing supports rapid material screening and product development, third-party testing provides independent, standardized validation; in all cases, results should be interpreted within the context of the intended chemical, exposure conditions, and real-world use scenario.

Real-world Use Scenario Considerations

Penetration and permeation information provides measurable insight into real world applications, but there are other factors to consider that may not be captured in these lab measurements. No single laboratory test can fully capture the complexity of workplace exposure and environmental conditions, making it essential to evaluate test results alongside garment design, application-specific hazards, garment wear trials, and operational practices to select the most appropriate level of protection.

Exposure intensity, duration, and direction can significantly affect risk, as can the presence of chemical mixtures, which may behave differently than individual substances tested in the laboratory. Garment compatibility with other PPE is also critical, since gaps or weak points at interfaces can compromise overall protection. It is also important to consider garment sizing and fit to reduce garment stress and gaps at garment interfaces.

Equally important are safe donning and doffing procedures; even when a garment performs as intended during use, improper decontamination or removal can result in contaminant transfer and worker exposure.

Another important consideration is material degradation, which helps assess chemical compatibility. Degradation describes how a material’s physical properties may change when exposed to a chemical (e.g. swelling, embrittlement, etc.), radiation (e.g. sunlight, heat, etc.), or physical stress (e.g. abrasion, puncture, etc.). Exposure to certain chemicals can alter a material’s physical properties, such as strength, flexibility, or appearance, potentially making it more susceptible to both penetration and permeation.

Reusable PPE introduces additional considerations, as decontamination is conducted to reuse the garments however the chemicals that permeate into the material may remain trapped even after surface cleaning, creating potential risks during handling or reuse. For these reasons, penetration, permeation, and degradation data should be considered together as part of a broader risk assessment.

This article originally appeared in the October 2026 issue of Occupational Health & Safety.