Why We Only Measure 0.5 and 5.0 micron Particles In Cleanrooms

Particle count measurement in clean rooms plays an important role in maintaining the cleanliness level of cleanrooms. Particle count in any cleanroom is measured by the particle counter which gives us a value after air filtration & monitoring. Particle count measurement in the cleanrooms is recommended by the various regulatory bodies and different guidelines like ISO, GMP, etc.

Common Practice

It is common practice that we measure only 0.5 and 5.0-micron particles in cleanrooms but a commonly asked question is why only we select 0.5 and 5.0 microns measurement?

What about less than 0.5 microns and more than 5.0 microns?

Before going to the details of the above questions first have a look over some basic facts about cleanrooms and types of particles.

0.5 & 5.0 micron particles

Why Cleanrooms?

Cleanrooms are established in pharmaceutical industries to perform various manufacturing, filling and dispensing activities. What is a cleanroom?

A cleanroom is a room having a controlled number of viable and non-viable particles.

Read Details of cleanrooms in following,

Cleanroom classification in pharmaceutical industries.

Types Of Particles In Cleanrooms

There are two types of particles which are measured in cleanrooms

and are given below,

  1. Viable Particles
  2. Non Viable Particles

What Is Viable Particle Count?

The process of counting the number of living microorganisms in a clean room is known as viable particle count. Viable particles are generated by the personnel working in the clean rooms.

Viable particles are not able to move from one place to another place.

How To Measure Viable Count?

  • The viable count is usually measured by the settle plate method & by using an air sampler having a media plate attached.

Example Of Viable Particles

  • Bacteria

What Is Non-Viable Particle Count?

Non-viable particles are non-living particles & do not have any living organisms.

Non-viable particles in cleanrooms work as a transporter or carrier  of living organisms.

The source of non-viable particles may be HVAC systems, processes and materials.

Why 0.5 & 5.0 microns?

  • As we discussed earlier, viable particles or living organisms are not able to move from one place to another place in cleanrooms,they need some source or medium for their movement.
  • These microbes attach to the surface of non-viable particles and move from one place to another place with the help of air movement.
  • So the number of particles is measured to keep it in the recommended range because if the number exceeds it may result in cross-contamination.
  • During particle count, we measure only 0.5 and 5.0-micron particles because most of the commonly found bacteria are in the size range of 0.5 to 5.0 micron so this size range is the main source of contamination.
  • The answer to the question of why we don’t measure less than 0.5 micron is that,
  • microorganisms find it very difficult to attach particles less than 0.5-micron size.
  • If the microbes attach to the particles greater than 5.0 micron then these particles become heavy and are not transported along with air movements but settle down on the ground.
  • This is the main reason we measure only 0.5 and 5.0-micron particles.

Read More

  1. Types of airlocks in pharmaceutical industries.
  2. Types and functions of HEPA filters.
  3. HVAC or Heating Ventilation & Airconditioning System.
  4. Why Do We Use Three Batches For Validation
  5. Pass Box In Pharma