How Clean Rooms Maintain Air Quality: The Role of Fume Extraction

Clean rooms and controlled environments rely on extremely strict air purity levels to protect sensitive processes, equipment, and in many cases, people. Whatever industry they’re used in, these environments must follow precise clean room air quality standards to prevent contamination.

At the heart of maintaining these standards is effective fume extraction. In this blog, we explore the essential role fume extraction plays in controlling air quality, supporting operating room safety measures, and how businesses can monitor and test their environments to ensure compliance.

What Are Clean Room Air Quality Standards?

Clean room classifications are based on the number and size of particles permitted per volume of air, according to standards such as ISO 14644-1 or the older Federal Standard 209E.

The ISO 14644-1 scale runs from Class 1 to Class 9, with Class 1 being the cleanest (fewest particles permitted) and Class 9 being the least restrictive. This scale helps determine which environments are suitable for various sensitive operations, from microelectronics to general industrial use.

ISO Clean Room Standards Explained:

• Class 1: Allows the fewest number of particles – used in ultra-sensitive settings like semiconductor manufacturing or nanotechnology environments.
• Class 2–4: Suitable for sterile pharmaceutical manufacturing, biotech applications, and critical research labs.
• Class 5–6: Common in medical device assembly and food production where moderate cleanliness is required.
• Class 7–8: Often used in general industrial processes, providing good air quality while being more cost-effective to maintain.
• Class 9: Equivalent to a normal room with basic filtration, class 9 clean rooms are used in less sensitive areas within controlled facilities.

Meeting these standards requires a combination of air handling systems, including HEPA filters, airflow management and targeted fume extraction solutions. At Purex, we’ve designed a wide range of fume extraction systems specifically for clean rooms to combat the unique challenges within the industry.

The Importance of Fume Extraction in Clean Rooms

While clean rooms are designed to control airborne particles, the production processes performed in these spaces often create harmful fumes, vapours and dust particles that need to be targeted at the source to protect operators. Common examples of harmful fume sources in clean rooms include:

• Soldering fumes when manufacturing electronics
• Chemical vapours when producing pharmaceutical products
• Disinfectant or sterilisation gases in the healthcare sector
• Biological particulates in laboratory work

By adopting a fume extractor to remove hazardous airborne substances at the source, you’re reducing the load on the general HVAC system, preserving the integrity of the clean environment and further protecting those operating within the space.

How to Test Air Quality in your Clean Room

Testing the air quality in your clean rooms is vital to ensuring compliance, ongoing safety, and product protection. Cleanrooms are often used to manufacture products that cannot be safely produced in uncontrolled environments. Even microscopic contamination can make products unsafe, lead to defects, and compromise entire batches, causing significant financial losses. That’s why rigorous air testing is so important.

Depending on the industry and cleanroom classification, businesses typically monitor:

• Particle counts using airborne particle counters. These devices detect and count microscopic particles, helping to verify that the cleanroom environment meets the ISO standard it’s classified under.
• Airflow direction and velocity using anemometers. These tools measure how air moves through the room to ensure clean air pushes contaminants away from sensitive areas.
• Contaminant levels of chemicals such as VOCs and ozone. Sensors and samplers help detect airborne chemical pollutants that may not be visible but still pose health or safety risks.
• Air exchange rates (ACH) to ensure appropriate ventilation. This dictates the number of times the air in the cleanroom is replaced every hour. For example, an ISO Class 5 cleanroom may require 240–600 ACH, depending on usage.

In addition to standard HVAC testing, fume extraction systems should be routinely serviced and tested to confirm capture efficiency and filter integrity. To learn more about safely maintaining your fume extraction system, read our blog: How to Maintain Your Fume Extraction System.

How Often Should You Test Air Quality in a Clean Room?

Regular testing is necessary to maintain clean room air quality standards. However, the frequency depends on the type of clean room and the processes being carried out inside it. In most cases, air quality should be tested monthly or quarterly, especially if your staff are regularly exposed to hazardous fumes or fine particles. However, testing may need to happen more often if you’ve recently replaced filters, changed extraction systems, or introduced new equipment.

Here are some guidelines on testing frequency:

• LEV Testing – at least once every 14 months as per HSE regulations.
• HEPA filter integrity testing – typically every 6 to 12 months, depending on the ISO class.
• Airflow and air velocity testing – usually conducted biannually or quarterly, especially in high-grade cleanrooms.
• Room pressure differentials and ACH (air change rate) testing – monthly or quarterly to ensure consistent airflow patterns.
• Particle counts – as frequently as weekly in ISO Class 5–6 cleanrooms, or monthly for lower classifications.
• Microbiological testing (for sterile environments) – typically monthly, or more frequently in healthcare and pharmaceutical settings.

Using air quality monitoring equipment or enlisting a professional ensures you're meeting ISO classifications and staying compliant with workplace safety regulations. At Purex, our fume extraction systems are designed with high-efficiency filtration to support these standards and help customers maintain peak air quality over time.

Clean Room Examples

Cleanrooms are used across various industries where air quality directly affects products and safety. This ranges from semiconductor manufacturing, where even microscopic particles can damage circuitry, to pharmaceutical production, where contamination could compromise the efficacy of medicines. Below, we’ve provided an example of how a clean room protects patients in hospital environments.

Hospital Clean Rooms

In healthcare settings, in particular operating theatres, air quality is about far more than regulatory compliance. It’s directly tied to patient safety. Therefore, there are several safety measures in place to ensure the environment is safe for both patients and doctors. These include:

• Laminar flow systems - these systems ensure a steady, unidirectional flow of filtered air, usually from ceiling to floor, to push contaminants downward and away from sterile zones like surgical tables.
• HEPA filtration - High-Efficiency Particulate Air (HEPA) filters trap 99.97% of particles as small as 0.3 microns, removing dust, bacteria, and other pathogens from the air before it reaches the cleanroom environment.
• Source capture systems - these are used to directly extract surgical smoke or anaesthetic gases at the source by using fume extraction arms or built-in evacuation port to reduce exposure risks to staff and patients.
• Routine air quality testing - regular testing helps track microbial loads, VOCs, and particulate levels to ensure the cleanroom remains within safe limits. This may involve particle counters, gas sensors, or microbiological sampling.

Need a Clean Air System? We Can Help

At Purex, we design clean air systems that help clients across healthcare, electronics and pharmaceutical sectors meet stringent ISO requirements. From our compact designs to our HEPA and carbon filters, our fume extraction systems are designed with real people in mind, offering maximum protection with minimal disruption to your operations.

Want to know more about how to meet clean room air quality standards or which extraction system best suits your clean room? Explore our recommended clean room systems or contact our team of experts.