Why are HEPA filters essential for a cleanroom environment?

I. Core Performance Advantages of HEPA Filters
The definition of a HEPA filter is "the filtration efficiency of particles with a diameter of 0.3 micrometers is ≥ 99.97%" (American standard). Its unique structure (such as the random stacking of ultra-fine glass fibers or polypropylene melt-blown materials) can capture tiny particles through multiple mechanisms such as interception, inertial collision, and diffusion.
II. Functional Requirements of Clean Rooms Depend on HEPA Filters
Clean rooms are widely used in the pharmaceutical, electronic, semiconductor, biological laboratory, and precision manufacturing industries. These scenarios have extremely strict requirements for air cleanliness (such as a Class 1 clean room requiring no more than 10 particles of ≥ 0.5 micrometers per cubic meter of air). The role of HEPA filters is reflected in:
Ensuring product quality and performance
Electronic/semiconductor industry: During chip and wafer production, even a 1-micron particle adhering to the surface can cause circuit shorting and yield drops. HEPA filters can control the particle concentration in the production environment to below millions or even billions, ensuring the stability of precision components.
Pharmaceutical industry: If there are microorganisms or dust in the production environment of injectables or sterile medical devices, it may cause drug contamination and patient infection. HEPA filters are the core equipment required by GMP (Good Manufacturing Practice) and directly relate to the safety of drugs.
Maintaining the stability of the experimental / production environment
Biological laboratory: When studying viruses, bacteria, or genetic engineering, HEPA filters can prevent harmful microorganisms from leaking (protecting operators), and at the same time prevent external bacteria from entering (avoiding sample contamination).
Precision optics industry: If there is dust in the processing / assembly environment of lenses and laser components, it will affect optical performance (such as light transmittance, imaging accuracy), and HEPA filters can ensure that the environmental cleanliness meets the optical grade standard.
III. Irreplaceability of HEPA Filters in Clean Room Systems
The air purification system of a clean room is usually composed of "primary efficiency → medium efficiency → high efficiency (HEPA)" three levels of filtration. Among them, the HEPA filter is the last and most crucial barrier:
Primary and medium efficiency filters can only remove large particles (≥ 10 micrometers) and cannot handle PM2.5-level tiny particles;
HEPA filters can directly filter particles with a diameter of ≥ 0.3 micrometers and have stable efficiency (the lifetime filtration efficiency decay is slow), and can maintain the designed cleanliness of the clean room for a long time.