Clean zone

Anything that enters an exclusion zone should be evaluated as to its potential contamination. If not removed properly, these contaminants may permeate PPE, tools, instruments, and other equipment [2]. In addition, this potential contamination can be transferred to the clean zones if it is not controlled. If contamination does get into clean zones, anyone may be able to take the contamination home with them to affect themselves, family members, and the general population. 

The primary contractor at Site A had identified clean zones, buffer zones, and related site control procedures in its written plan however, onsite implementation differed from those specified in the plan. For example, the exclusion zones identified in the plan at the upper pad of the wastewater treatment plant, the dredge area, and the solid waste storage area were marked with signs requiring PPE, but were not labeled with red banners as called for in the plan. In addition, the exclusion zones did not have controlled access through one point of entry as described in the plan, nor were the buffer zones established and demarcated with yellow banners. 

At Site I, personnel and equipment decontamination procedures were not monitored for their effectiveness in accordance with HAZ-WOPER requirements. The Site I subcontractor did not have provisions for particulate sampling, evaluating exposure to pesticides and herbicides, or evaluating the effectiveness of site zone boundaries and personnel decontamination procedures. Additionally, monitoring had not been conducted to verify that decontamination was not necessary for employees who leave the exclusion zone and enter a clean zone without undergoing decontamination. 

Air curtains and jet-assisted hoods separating dirty zones from clean zones (Fig. 7.109e)... 

Another factor influencing contaminant and heat transfer from dirty to clean zones against the stable airflow is a turbulent exchange between these zones. This process should be considered in the design of displacement or natural ventilation systems and evaluation of the emission rate of contaminants from the encapsulated process equipment (Fig. 7.111a). 

The purpose of open unidirectional airflow benches is to protect products from particulate contaminants by creating a controlled environment. These benches are used, for example, in electronic, biological, pharmaceutical, and food industries. It should be mentioned that within pharmaceutical production, aseptic sterile processes must be carried out in a Class 100 environment (U.S. Federal Standard 209 E, Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones). To avoid particle contamination in the bench, horizontal or vertical airflow with high-efficiency particulate air (HEPA)-filtered air is used. The air velocity is normally 0.4-0.5 ra s". Some examples of typical arrangements of open unidirectional airflow benches are shown in Fig. 10.51. 

Clean zone Any area, such as a clean room, in which set standards of air purity and other environmental conditions are maintained. 

A high neutron porosity and low density porosity occur in the shale zones 2256-2274 and 2356-2388 ft. In the clean zone, around 2280-2290 ft, the cleanest part reads = 18% and = 13%. Plotting the point in the CNL chart of Figure 4-303, the rock matrix appears to be a dolomitized limestone and the true porosity is 17%. 

These test procedures are performed to determine average air flow velocity and uniformity of velocity within a cleanroom, clean zone, or unidirectional flow work zone, as well as to determine air supply volume uniformity. 

Air flow velocity (nonunidirectional) test In a nonunidirectional clean room or clean zone, air flow velocity measurements should be made for each terminal HEPA Alter (or supply air diffuser, if applicable) there is no entrance plane as such. 

The average air flow velocity, or the average or total air flow volume, for the clean room or clean zone should be within 5% of the value specified for the clean room or clean zone, or within other standardized tolerance limits. 

The minimum number of sample locations required for verification in a clean zone with unidirectional airflow shall not be less than the lesser of (a) or (b) ... 

A controlled environment such as a clean zone or clean room is defined by certification according to a relevant clean room operational standard. Parameters that are evaluated include... 

It should be ensured that the sampling locations are evenly distributed throughout the area of the clean room or clean zone and positioned at the height of the work activity. 

The clean room or clean zone is deemed to have met the specified air cleanliness classification if the averages of the particle concentrations measured at each of the locations and, when applicable, the 95% upper confidence limit, do not exceed the concentration limits required [13,15,19],... 

Federal Standard 209E. Airborne Particulate Cleanliness Classes in Cleanroom and Clean Zone (Sept. 11, 1992). 

IES (1992), Institute of Environmental Sciences, Federal Standard 209E, Airborne particulate cleanliness classes in cleanrooms and clean zones, Mount Prospect. Available at http //www.set3.com/papers/209e.pdf (accessed October 2006). 

Reinmuller, B. (2000), Microbiological risk assessment of airborne contaminants in clean zones, Bulletin No. 52, Royal Institute of Technology/Building Services and Engineering, Stockholm. 

Clean Zone This is the treatment area inside of the emergency department or hospital where newly... 

Warm/Dirty Adjacent to the hospitai, usuaiiy near the Emergency Department (remote to the reiease site) Hospitai decontamination area. This area needs a source of water (coid ciimates require a warm water source) for decontamination and barriers to controi entrance and exit from the area, which must be tightiy controiied. Personnei working in this area (first receivers) have potential to be exposed to the contaminant(s) and, therefore, must wear the appropriate level of PPE (level C minimum). At the entrance to the Warm Zone is the initial triage station. All ambulance and walk-in cases must enter the facility after going through this triage station. Victims who are clearly not contaminated skip the Warm Zone and enter the Cold (Clean) Zone directly. All others proceed into the Warm Zone for decontamination. 

Soap, brushes, sponges and other equipment used for decontamination should be placed in atrashcan and not carried into the Support Zone (on-scene) or the Cold (Clean) Zone (hospital setting). 

The set up and use of the decontamination area must be careftdly thought out. Often, the area is split into different zones (Rotenberg et al, 2003). At a minimum, there must be a dirty contaminated zone and a clean decontaminated zone. It is critical to emphasize that traffic must go one-way between zones. This will eliminate the possibility of a cleaned patient becoming cross-contaminated or an exposed patient entering a health care facility before being decontaminated. Security personnel must be utilized to make sure patients do not consciously or unconsciously violate the rules. A secondary triage will be needed as patients enter the clean zone to allow patients to receive antidotes or be referred for further care. Keep in mind that for severely ill patients, antidote administration may precede decontamination. 

Many firms use the so-called clean-zone concept, in which the restrictions on personnel entering a production area and the required protective clothing are based on the nature of a product— whether the product is prone to the growth of microbes or whether it is required to be sterile. Even for products not required to be sterile or that are not supportive of microbial growth, this concept controls the production environment through reduction of bioburden. 

Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones Federal Standard 209E Federal Supply Service, General Services Administration Washington, DC, 1998. 

Ljungqvist, B. Reinmiiller, B. Interaction between air movements and the dispersion of contaminants clean zones with unidirectional air flow. PDA J. Pharm. Sci. Technol. 1993, 47 (2), 60-69. 

Unidirectional airflow is a rectified airflow over the entire cross-sectional area of a clean zone with a steady velocity and approximately parallel streamlines (see also turbulent flow). (Modern standards no longer refer to laminar flow, but have adopted the term unidirectional airflow.)... 

Note The process core is regarded as the most stringently controlled clean zone which is protected by being surrounded by clean areas of a lower classification. 

The high pressure differential between the clean and less clean zones should be generated by leakage through the gaps of the closed doors to the cubicle. 

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