The contamination of classified rooms is a real challenge for the pharmaceutical industry. The fluids used for the production (water, clean steam and vapor of gas) are a potential source of product contamination and crosscontamination from one room to another. The quality of the fluids used should be under control in order to guarantee the quality of the product manufactured on site. The quality of the pharmaceutical water (purified water or water for injection) is mastered for many years by the pharmaceutical industry and undergoes specific qualification and monitoring plans. Based on this experience, the authorities are focusing now on the quality of pharmaceutical gases. Indeed, gases are used during the production process as an excipient or "invisible helper" in contact of the products such as inerting agent. Gases that are commonly used in the pharmaceutical industry are: Nitrogen for inerting or flushing, Air for flushing, Oxygen for fermentation, Carbon dioxide for extraction and purification, etc. (the quality of those gases is specified in the European and U.S. pharmacopeias). Performing the testing of those gases is a real challenge for the industry since it requires: Dedicated analytical equipment according to the pharmacopeias with the appropriate qualification; Dedicated sampling method fully validated; Trained and qualified technician with special focus on safety and security issues. In addition, the quality evaluation should be performed at the use point and means access to classified areas. Analyzing gases within a production environment involves testing them upon receipt at the facility as well as subsequent tests when the system is operational and after any changes or intervention to the production systems are made. The aim is to verify the absence of any potentially hazardous or disruptive materials. Besides the pharmacopeias specifications, the gas should also be tested in terms of particular contamination and bio contamination. The contamination of the gas should not be higher than the contamination of the room where it is used. As an example, a gas used in an ISO 5 room, corresponding to the class 100, should be analysed according to the ISO 5 specification in terms of particles contamination. Contract Pharma Analytical service providers have developed the full set of methods with all the dedicated equipment to perform all the tests required for the evaluation of the quality of the gases and the qualification of the pipe works for the pharmaceutical industry.