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Compressed air is increasingly used as a process gas source in pharmaceutical manufacturing processes. As it comes into direct contact with raw materials, excipients, and inner packaging materials, it becomes an important factor that directly affects the quality of drugs. At present, China’s \"Drug Administration Law\" and \"Regulations for the Implementation of the Drug Administration Law\" only contain general provisions regarding pharmaceutical-grade compressed air; as a result, enterprise standards and production techniques vary widely, which severely affects the quality of drugs. Based on the results of GMP inspection checks for pharmaceuticals in various provinces and cities, problems related to compressed air production systems keep emerging, and the reason for this is that pharmaceutical companies do not have a sufficient understanding of the technology behind such systems. https://pic3.zhimg.com/80/v2-0fa4d19532587aa6108e99050f71d14d_720w.jpg As shown by the results of the first unannounced inspections conducted by the Henan Provincial Drug Administration on pharmaceutical companies in 2020, among the 65 companies inspected, 6 were found to have 8 issues related to the compressed air production systems that required correction. Each cubic meter of air in the environment contains around hundreds of millions of dust particles, with a large number of bacteria attached to these particles. The relative humidity of the air is generally above 45%, and there are also gaseous pollutants such as hydrocarbons in the atmosphere. There are more pollutants in the air during foggy weather. During compression and delivery, air inevitably comes into contact with machine components; therefore, the compressed air produced by air compressors contains the following impurities: ① Solid particles: The air intake filters of air compressors are unable to remove particles from the air, and these solid particles increase after compression ； ②Water: When air is compressed and condensed, it becomes wet saturated air, containing a large number of liquid water droplets. Even in pure saturated air after separation, condensation still occurs as the temperature drops ； ③Oil: Oil droplets formed by the compression of air, liquid oil, oil mist, and lubricating oil used in high-speed, high-temperature air compressors to provide lubrication and sealing – all of these end up in the compressed air and cause contamination ； ④Microorganisms and unpleasant odors. 1 Uses and quality requirements for compressed air in pharmaceutical manufacturing 1.1//The main uses of compressed air: In pharmaceutical manufacturing companies, the compressed gases that are commonly used include air, nitrogen, and carbon dioxide. Among them, compressed air is the most widely used as a process gas source for: ▶ bottle manufacturing, blowing, cleaning, and transportation of plastic bottles ； ▶ Pneumatic cleaning, sorting, and conveying of plastic bottle caps ； ▶ Solution preparation, liquid pumping, and filling ； ▶ Closed transportation of solid materials ； ▶ Process steps such as liquid spraying in spray drying equipment and one-step granulators. 1.2//The hazards of compressed air impurities to pharmaceuticals: When used as a process gas source, compressed air comes into direct contact with materials and pharmaceuticals. When used as a power source, although it does not come into direct contact with drugs, it is mostly used within a clean area. Therefore, compressed air for pharmaceutical use must be clean compressed air. Pharmaceutical manufacturers primarily need to control the water content, oil content, dust particle content, and biological particle content in the compressed air, and they also require that the compressed air have no unpleasant odor. Oil-containing compressed air in direct contact with medicines can contaminate them and promote bacterial growth. Moisture accelerates bacterial growth and causes medications to absorb moisture and deteriorate. https://pic4.zhimg.com/80/v2-72a0df94c87d50d4e53acf62b94710d2_720w.jpg The air contains a large amount of dust particles and microbial particles, with the latter being more harmful to the human body. Microorganisms mainly refer to bacteria and fungi; when they contaminate products, they not only cause the products to become contaminated and spoil, but if used improperly, they can enter the human body either through intestinal or non-intestinal routes, directly affecting human health and leading to serious consequences. https://pic1.zhimg.com/80/v2-b33f8014087aaf7b4c05af88c9598b11_720w.jpg1.3//Air quality standards for use in pharmaceutical manufacturing▶Solid particles: According to the 2010 version of GMP, the highest cleanliness level required for cleanrooms used in the production of sterile drugs is Class A. Accordingly, the cleanliness grade of the compressed air used in the clean areas for sterile drugs should be set at Class A. For the production environment of non-sterile drugs, GMP stipulates that the D-class standards for sterile drugs should be followed. The compressed air used in the cleanrooms for sterile drugs must meet at least Class C standards. ▶ Water content: To prevent condensation in the system, the dew point temperature is generally set at 5–10 °C lower than the lowest temperature that the compressed air pipelines and the equipment using the air might experience, depending on the location and season. ▶ Oil content: It mainly focuses on controlling oil droplets, suspended oil mist, and oil vapor in compressed air. Refer to the requirements in **standards regarding the quality of compressed air for food and beverage processing; the standards for pharmaceuticals should be stricter than those for food, meaning that the maximum oil content should be kept below 0.01 mg/m3. ▶ Microorganisms: Tested in accordance with the methods for microbial limits specified in Part IV of the 2015 edition of the Chinese Pharmacopoeia ； Sterile drugs are tested in accordance with the sterility testing method, with a standard of 1 CFU/m3 ； Non-sterile products are tested using the microbial counting method, with a standard of less than 10 CFU/m3. ▶ Colorless and tasteless: It must not contain any gases other than those present in normal air. Carbon monoxide is the most dangerous contaminant in compressed air, with the exhaust gases generated during the operation of the air compressor itself being its main source. Therefore, control the level of carbon monoxide