Risk-Based Module for Selecting Air Monitoring Sites for Environmental Monitoring Programme

 Environmental monitoring is crucial. It’s how we keep tabs on both live microbes and non-viable particles floating in controlled, classified spaces within pharmaceutical facilities. “Controlled and classified” refers to areas defined by WHO standards, where different cleanliness levels are required for different activities. WHO divides clean rooms into Class A, B, C, and D. We can find these classifications in Annex 6 of the WHO Good Manufacturing Practice for pharmaceuticals (Technical Report No. 961, 2011).

 Why use a risk-based approach to pick sampling locations?

Because environmental monitoring isn’t just a formality. Both USP-NF (1116) and WHO guidelines stress the importance of choosing sampling sites carefully—don’t just place plates anywhere and call it monitoring. Many pharmaceutical companies overlook this and end up sampling the wrong areas, missing the true picture of microbial loads in their environments. Every facility is unique. Air exchange rates, HEPA filter performance, facility layout, activities conducted, and even operator hygiene—all influence what you find and where you find it.

 Here’s how to assemble a risk study team:

-  Members from Quality Control.

- Representatives from Quality Assurance.

- Representative from Production.

 Select your study locations thoughtfully. Focus on areas where contamination risk is higher or cleanliness is especially important. Typically, this includes:

- Dispensing room

- Granulation room

- Compression room

- Suspension preparation room

- Tablet inspection room

- Primary packing room

 Inside each room, target:

- Areas near operating machines

- High-traffic spots

- Difficult-to-clean corners

- Locations near return air vents

- Spots near drains—common sources of contamination

- Any other problem areas you observe

 How to conduct the test:

Test: Settle Plate Method

Test Condition: Dynamic

Duration: At least 3 days

Media: Soybean Casein Digest Agar (for total aerobic microbes) and Sabouraud Dextrose Agar (for yeast and mold)

Exposure time: 4 hours per plate

Incubation: Soybean Casein Digest Agar—48 to 72 hours; Sabouraud Dextrose Agar—5 to 7 days

 Steps:

1.      Place plates of each medium at your chosen sites using a petriplate stand.

                                                          Fig: Culture plate on Stand

2. Leave them open for 4 hours.

3. Carefully retrieve the plates and transport them to the microbiology lab, maintaining sterility.

4. Incubate the Soybean Casein Digest Agar plates for up to 72 hours and the Sabouraud Dextrose Agar plates for up to 7 days.

5. After incubation, count the colonies with a colony counter

 

Fig: Culture media class="MsoNormal">6. Interptetate the results

 Conclusion:

Review the data. Now you’ll know which spots have higher microbial counts. Use this information to finalize your sampling sites for ongoing environmental monitoring in your facility. This way, you’re not just guessing—you’re tracking what truly matters.