We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What Are Cleanroom Classifications?

By Jillian O Keeffe
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Cleanrooms are industrial rooms that are cleaner than regular rooms, containing less dust, fewer microorganisms and fewer particles in general than a regular room. Pharmaceutical companies, medical device companies and other types of companies use cleanrooms to manufacture sterile products. Cleanroom classifications vary by regulatory standard, but some of the standards overlap. Each class of a particular standard is allowed to contain a maximum number of particles of a certain size for a specified volume of air. Usually, the specified volume of air is a cubic meter or a cubic foot.

The International Standards Organization (ISO) has cleanroom classifications from ISO 1 to ISO 9, with ISO 1 being the cleanest of all and ISO 9 being the least clean. ISO 1 rooms are allowed to contain no more than 10 particles of 0.1 micrometers per cubic meter of air and no more than two particles of 0.2 micrometers per cubic meter of air.

In some countries, there are several standards applied to cleanrooms, depending on which regulatory standards a factory has to satisfy. For example, the United States uses Federal Standard 209 and ISO Standard, and European factories use ISO standard and European Union pharmaceutical cleanroom classifications, although Great Britain might also use British Standard.

The reason why cleanrooms are classified is that many items, such as drug products to be injected into a vein, need to be sterile. Contamination with microorganisms or particulates can be dangerous for the consumer. Non-sterile products, such as ointments, should be kept as free from contamination as possible, but it is not necessary to package them in a completely sterile manner.

Cleanrooms generally are tested for particles under certain conditions. The standard specifies whether the area is to be at rest, which means that the room is operating as normal but there has been no personnel movement for a specified time, because people can create eddies that kick up settled particles from the floor into the air. An analyst will use a particle meter to draw through the specified volume of air, and the meter will count the particles.

Cleanroom classifications also help divide areas of manufacturing. For example, the European pharmaceutical cleanroom classifications divide areas into Grade D, Grade C, Grade B and Grade A, with Grade A being the cleanest. Grade D is a staging area, where materials are prepared for entry into Grade C. Grade C is where the solution is prepared, and Grade A is where the sterile product is filled. Grade B is the area around Grade A that the filling workers walk around in to transfer the product from Grade C to Grade A.

The U.S. standards range from M1 to M7, with M1 the cleanest class. The M1 limits for 0.1-micrometer particles is 350 per cubic meter and 75.7 0.2-micrometer particles per cubic meter. The British classification system uses the letters C to M, with C the cleanest room. It does not test for particles smaller than 0.1 micrometer and allows up to 100 0.3-micrometer particles.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.