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Compressed air is increasingly used as a process gas in the manufacturing of pharmaceuticals. 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 the final drugs. To date, there are no unified, legally established standards for the quality of medical-grade compressed air. China’s \"Pharmaceutical Administration Law\" and its implementing regulations only provide general guidelines on this matter; as a result, the standards set by various companies and the manufacturing techniques employed vary widely, which severely impacts drug quality. 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. For example, the results of the first unannounced inspections conducted by the Henan Provincial Drug Administration on pharmaceutical companies in 2020 showed that among the 65 companies inspected, 6 of them had 8 issues related to their compressed air production systems that required correction. There are approximately hundreds of millions of dust particles per cubic meter of air in the environment, with a large number of bacteria attached to these particles; the relative humidity of the air is generally above 45%. 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 intake filters of air compressors are unable to remove particles from the air, and these solid particles increase after compression; 2. Water: When air is compressed, it becomes wet saturated air, containing a large number of liquid water droplets. Even in pure saturated air that has been separated, condensation still occurs as the temperature drops; 3. Oil: The oil contamination present in the air cannot be ignored either after compression. Air compressors that operate at high speeds and temperatures use lubricating oil for lubrication and sealing purposes, but this oil can end up contaminating the compressed air; 4. Microorganisms and certain harmful chemical substances. Solid particles, moisture, and oil not only cause damage to the gas supply system but also lead to the following adverse effects in practical applications. 1. Microbial particles in compressed air can contaminate products; 2. Oil vapors mixed in compressed air can accumulate to such an extent that they become a source of explosion and fire risk. When lubricating oil vaporizes, it forms organic acids that can corrode the inner surfaces of compressed air pipes. Once oil contamination reaches a certain level, it will accumulate in the pipes, contaminating them as well as the raw materials; 3. The tiny particles present in compressed air can easily damage pneumatic components, and more seriously, they can contaminate the materials being processed; 4. Moisture contained in compressed air will saturate and form water droplets under certain temperature and pressure conditions. When compressed air comes into contact with materials, this can have a serious impact on the quality of those materials. These impurities can affect the production process and product quality; they may even cause the products to deteriorate, resulting in financial losses and even serious consequences. To ensure drug quality, technical parameters such as the particle count, moisture content, oil content, and microbial count in compressed air must be controlled. Equipment for producing compressed air includes: conventional air compressors or oil-free air compressors used to reduce oil content; adsorption drying can be employed to remove moisture; and multi-stage filtration can be used to filter dust particles from the air. These methods improve the purity of compressed air, but they still have significant shortcomings: ① The number of microorganisms in compressed air is high, resulting in a low pass rate for quality checks; ② The oil content in the air is often overlooked, with the assumption that the use of oil-free compressors means there is no need to worry about high oil levels. In fact, even when oil-free compressors are used, if the air quality in the manufacturing facility is poor and the compressed air is not further treated to remove oil, it is still difficult to meet pharmaceutical-grade standards. The main types of compressed gas used in pharmaceutical manufacturing companies include air, nitrogen, and carbon dioxide. Among them, compressed air is the most widely used. As a process gas source, it is employed in processes such as the manufacturing, blowing, cleaning, and transportation of plastic bottles; the gas cleaning, sorting, and transportation of plastic bottle caps; the preparation of pharmaceutical solutions, the pumping of liquids, and filling; the sealed transportation of solid materials; as well as in spray drying devices and the spraying process in one-step granulation machines. The hazards of compressed air impurities to pharmaceuticals: When used as a process gas, compressed air comes into direct contact with materials and pharmaceuticals. When used as a power source, it does not come into direct contact with drugs, but 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 levels of moisture, oil, dust particles, and biological particles 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 the growth of bacteria. Moisture accelerates bacterial growth and causes medications to absorb moisture and deteriorate. The air contains a large amount of dust particles and microbial particles, the latter of which pose a greater threat to the human body. Microorganisms mainly refer to bacteria and fungi; when they contaminate products, they not only cause the products to become infected and deteriorate. If ingested accidentally, whether through intestinal or non-intestinal routes, they can directly affect human health and lead to serious consequences. In accordance with the requirements of the Drug Administration Law, drug production must be carried out in compliance with the Good Manufacturing Practice for Drugs (GMP). GMP requires that all materials entering the clean area be purified. Therefore, compressed air used in pharmaceutical manufacturing must be managed and controlled in accordance with GMP requirements to ensure the quality and safety of drugs. Compressed air quality grade standards: Standard SO8573.1 classifies contaminants in compressed air into three types: solid impurities, water, and oil. Our country has adopted this standard as well. Quality standards for compressed air used in pharmaceutical manufacturing 1. Basis for establishing corporate quality standards At present, there are no international or **legal quality standards for compressed air used in pharmaceutical applications. Article 42 of Chapter 8 of the \"Good Manufacturing Practice for Pharmaceutical Products (Revised in 2010)\” stipulates that the production gases used in sterile production areas (such as compressed air and nitrogen, but not including flammable gases) must undergo sterilizing filtration, and the integrity of the sterilizing filters and breathing filters should be checked regularly. **The \"Guidelines for Drug Production Validation (2003)\) compiled by the Food and Drug Administration sets out the technical requirements for compressed air used in pharmaceutical manufacturing. For compressed air that has undergone terminal sterilizing filtration, the microbial count should