The very first cleanroom application considered by historians is in the medical field, dating back to the mid -19th century. The ventilation system and highly controlled environment in the hospital effectively prevent disease transmission, saving millions of lives. Some believe that the earliest modern cleanrooms were built in the early 1950s. There is evidence proving that HEPA filters were used to prevent cross-contamination in the manufacturing industries. 

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Cleanroom applications can now be found in many leading industries. For example, Pharmaceuticals/Biotechnology, Microelectronics/Semiconductors, Flat Panel Display, Aerospace, Hospitals, optical manufacturing, advanced martial research and food processing. Cleanroom equipment and manufactured products are susceptible to contamination, including smoke particles, flames and heat. Potential fire threats damage or destroy valuable products and manufacturing lines directly and impose indirect costs to the business, such as termination of the manufacturing process, decontamination costs, direct business interruption, and disruption of downstream customers.

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PNED particle charging ASD is highly sensitive to the smoke particles generated at the incipient fire, especially at the pyrolysed stage. Furthermore, sampling points and the sampling pipes feature high flexibility to reach the high ceiling area and void space, increasing the total coverage area. Additionally, the advanced particle charge concept allows PNED C-Ultra ASD to provide a reference measurement of cleanroom cleanliness. The advantage of the concept of particle charging is that the number of charges on the smoke particle is a function of particle surface area. Regardless of geometry, composition, and chemical properties, the smoke particle can be fully charged under specific charging conditions. This advantage has established a theoretical cornerstone for measuring nanoscale contaminant concentrations, making monitoring the cleanroom contamination level possible. At present, the PNED C-Ultra ASD fire early warning detector is capable of delivering effective and reliable particle concentration reference measurements for cleanroom complying with Class 6, 7, and 8 ISO14644 standards while providing even higher performance for very early fire alarms.