Environmental Monitoring of Cleanrooms

Validation helps ensure cleanrooms meet specific ISO standards. Such standards regulate degrees of cleanliness and are defined by factors such as particle count and size, air change rates, and more parameters outlined in ISO 14644-1. These classifications also help ensure the integrity of products that may be contained in a cleanroom.

The validation process naturally requires inspection and testing, but also means that cleanrooms must perform ongoing monitoring to demonstrate continued compliance (as these standards are never “one and done” and require everyday check-ins).

Cleanroom Validation Parameters

Cleanroom ISO Classes (1-9) are based on air cleanliness by particle concentration, with specific maximum allowable concentrations (particles/m3) for particles from 0.1 to 5 µm. Particle counts must be performed in accordance with ISO 14644-1, and must be repeated periodically to demonstrate ongoing compliance.

If you’ve worked in a controlled environment, then you can agree that “periodically” is not a scientific milestone. A myriad of things can go wrong during the built-in time gaps. For a multitude of reasons, air cleanliness can shift moments after a count, samples may be compromised, and tests could fail.

This is precisely why when it comes to monitoring particle counts, most facilities opt for 24/7 real-time monitoring instead of periodic “check-ins.” Look at it this way: A periodic check-in is akin to using an at-home COVID test. The test is only able to collect the data for that single point in time, and the results might not hold true even moments later.

Particle counts are only the tip of the iceberg: there are a plethora of tests and parameters outlined in ISO standards that could impact daily compliance in your cleanroom(s). For instance, tests for:

• Ultrafine airborne particles
• Macroparticles
• Airflow
• Air pressure difference
• Temperature
• Humidity

Thankfully, most parameters can be incorporated into a monitoring program that can ensure a more controlled cleanroom environment.

Relative Humidity vs. Absolute Humidity

To understand Relative Humidity (RH), we must first speak about Absolute Humidity.

Absolute Humidity 

Absolute humidity measures the amount of water vapor in the air, regardless of the air's temperature. Even as changes in the temperature of the measured environment occur, absolute humidity stays the same  (so long as the moisture content of the air remains unchanged).

Relative Humidity

Relative humidity is expressed as a percentage and measures the amount of water vapor present in the air relative to the maximum amount the air can hold at a given temperature. In other words, relative humidity indicates how close the air is to being fully saturated with vapor at that temperature.

Since warm air holds more moisture than cold air, the relative humidity level will decrease as the air temperature increases –even if absolute humidity stays the same.  Conversely, the relative humidity level will increase as air temperature decreases since colder (and therefore denser) air cannot hold as much water.

The graphs below illustrate the interplay between temperature and relative humidity.

We can assume that periodic increases and decreases in room temperature are related to the cycling “on/off” of an air conditioner or heater. Where we see peaks and valleys at room temperature, we alternately see valleys and peaks in the relative humidity.  

In instances where the graph does not show an expected inverse relationship between temperature and relative humidity, other factors could be at play.  A change in humidity could be affecting the temperature (instead of the other way around). When observed this way, there might be a lag time between cause and effect.  Other reasons could be related to air being introduced from outside the room or sunlight shining directly at or near a probe. It should also be noted that a decrease in air pressure can result in a decrease in relative humidity, and vice-versa.

Proper Probe Placement & Best Practices

Relative Humidity and Temperature (RH&T) sensors should never be placed in proximity to equipment that could affect readings such as HVAC duct vents, humidifiers, cooling or heating coils, blowers, incubator doors, sources of water, other sensors, aerosols, etc.

Another interesting consideration:  with cheaper RH&T sensors, the internal electronics heating up inside their housing can affect the temperature of the probe and negatively affect readings.

The Case for Proactive Cleanroom Environmental Monitoring

Is ISO enough for a cleanroom?

Let’s assess airborne particle count in relation to ISO standards. Despite the detailed test procedures that specify the number of sample points, sampling locations, apparatuses, and data required for reporting according to ISO 14644-1, users are only getting a snapshot of the cleanroom environment. Without continuous data for particle count and other critical parameters, it is impossible to identify abnormalities that can impact samples and products. 

Challenges also arise when clean rooms rely on multiple monitoring devices and platforms to obtain a complete understanding of the cleanroom environment. Not only might these devices be “speaking different languages” (making it difficult to evaluate parameters concurrently) but manually compiling data from different platforms is time-consuming, costly, and prone to error. 

What Can Happen if a Cleanroom is Not Monitored?

• Contamination risk
• Compromise sample integrity
• Legal penalties/ operational shutdowns
• Delays issue detection
• Skewed experimental results
• Unreliable data
• Setbacks in drug development
• Product recalls
• Health risks
• Waste of resources
• If there’s a disaster, you have to restore the cleanroom environment

The most effective means of cleanroom environmental monitoring comes down to the software, hardware, and service – that’s where XiltriX comes in.

Read more about monitoring environmental conditions in our eBook: Laboratory Environmental Monitoring.

The Solution for Proactive Laboratory Cleanroom Monitoring

The XiltriX system is designed to provide reliable monitoring of your facility’s numerous parameters in a single solution.

XiltriX integrates data collection from an array of sensors, assets, and equipment, offering comprehensive data analysis, reporting, and documentation. It delivers real-time insights on various parameters critical to both research and product integrity.

In addition to particle counting, our Monitoring-as-a-Service solution can measure temperature, relative humidity, differential air pressure, VOCs (volatile organic compounds), gases, light intensity, vibration, and additional parameters that provide valuable insight into the cleanroom environment. 

Within highly controlled cleanroom environments, fluctuations in critical parameters can have significant consequences for the experiments and products contained within. XiltriX provides data acquisition, analysis, and reporting on all equipment and environmental parameters to ensure optimal cleanroom environments. 

XiltriX provides a comprehensive validation support packet that includes Installation Qualification (IQ), Operational Qualification (OQ), and Performance Qualification (PQ) documentation and built-in reports. This enhances and simplifies ongoing testing, ensuring adherence to stringent standards and regulations.

If you’re interested in learning more about  the environmental monitoring of cleanrooms and how XiltriX can help, download our white paper on "Critical Parameters for Cleanroom Monitoring."