Small But Mighty
In controlled environments like pharmaceutical cleanrooms, hospital operating theatres, and food manufacturing facilities, monitoring air quality isn’t optional—it’s essential. The right air quality monitor, paired with a reliable environmental monitoring system, helps ensure product safety, regulatory compliance, and patient or consumer wellbeing. Among the most commonly used tools in these systems are active air samplers and passive sampling methods, each with unique strengths depending on your facility’s needs.
Let’s break down the key differences, how they work, and when to use each.
What Is Active Air Sampling?
Active air sampling involves mechanically drawing a known volume of air through a collection medium—such as an agar plate or a filter—using an active air sampler. This method provides quantitative data and is highly effective for detecting microbial or particulate contamination in real-time or at set intervals.
How it works:
Air is pulled into the sampler at a controlled flow rate. Microorganisms or particles in the air impact or are captured on the sampling medium. These samples are then incubated or analysed for further insights.
Use cases:
- Pharmaceutical manufacturing (especially Grade A and B cleanrooms)
- Hospital sterile zones and theatres
- Any application where regulatory compliance (e.g., TGA, EU GMP Annex 1, ISO 14698) is a must
- Validation of HVAC and HEPA filtration performance
What Is Passive Air Sampling?
Passive air sampling, often referred to as “settle plate” sampling, doesn’t require a pump or airflow. Instead, it relies on gravity: exposed agar plates are placed in various locations, and particles or microbes settle onto the surface over time.
How it works:
Plates are exposed for a fixed period (commonly 1–4 hours). After exposure, the plates are incubated and analysed for colony-forming units (CFUs). Results are qualitative and indicative rather than quantitative.
Use cases:
- Routine trending in cleanrooms or laboratories
- Environmental assessments where active sampling is not practical
- Situations with minimal airborne activity
- Early-stage facility monitoring during construction or qualification
Key Differences at a Glance
| Feature | Active Air Sampling | Passive Air Sampling |
| Air volume control | Yes, fixed and measurable | No, uncontrolled |
| Quantitative | Yes | No |
| Detection sensitivity | High | Lower |
| Equipment required | Yes – active air sampler | No – just agar plates |
| Cost | Higher | Lower |
| Use case | Regulated, high-risk zones | General monitoring or trending |
Which Should You Choose?
Choosing between passive and active air samplers depends on what you’re trying to achieve. An active air sampler gives you precise, reliable, and repeatable results—perfect for validated zones and areas requiring proof of compliance. On the other hand, passive sampling is low-cost, easy to set up, and ideal for ongoing trend analysis or supplementary monitoring in less critical areas.
For comprehensive risk management, most facilities use a combination of both, supported by a robust environmental monitoring system and integrated air quality monitor network to track and record data in real-time.
Regulations such as ISO 14644-1 and ISO 14698, along with standards from Australia’s TGA and global frameworks like the US FDA and WHO GMP, all recommend air monitoring strategies that include both active and passive methods, depending on room classification and intended use.
The Role of Data and Compliance
Regardless of your sampling method, the data you collect needs to feed into a wider environmental monitoring system. Today’s systems offer wireless data logging, cloud-based storage, automated alerts, and seamless integration with Building Management Systems (BMS). This ensures that any deviation in air quality—from microbial presence to particle counts—is detected and addressed quickly in real-time.
According to the Australian Therapeutic Goods Administration (TGA), facilities producing sterile medicinal products must ensure that “environmental monitoring data supports a state of control.” Without a proper air quality monitor strategy, maintaining this control becomes nearly impossible.
Choose the Right Approach for Reliable Results
When it comes to air sampling, there’s no one-size-fits-all solution. The best approach is a layered one, combining the quantitative power of an active air sampler, the accessibility of passive methods, and the real-time insights of an environmental monitoring system. Together, they help maintain control, reduce contamination risks, and support ongoing compliance in any facility where air quality matters. Whether you’re building a monitoring strategy from scratch or fine-tuning your current program, investing in the right air quality monitor setup—alongside expert guidance—can make all the difference.