Facilities Water & Air

Location and centralization

Disinfection of semi-critical or non-critical devices takes place at point of use or can be partially centralized. Sterilization of critical medical device is most commonly performed in a central sterilization department
Distance between centralized reprocessing services and point of use varies according to hospital configuration and strategy. Sterilization can be shared between different hospitals or subcontracted to external service providers.

Advantage of centralization are the access to the skills and quality management system of an organization dedicated to device reprocessing. Potential drawbacks are of logistic nature when distances between the reprocessing service and point of use of medical devices increase. For sterilization of critical medical devices, advantage/drawback ratio is typically in favor of centralization.

Devices reprocessing premises are adapted to the operations carried out and volume of activity being performed. In all cases, they must be easy to clean. Working conditions of personnel such as air quality, temperature, humidity, ergonomics and light, in particular must support compliance with good hygiene, , use of appropriate protective equipment/outfits, and hand-washing procedures. For reprocessing of flexible endoscope see flexible endoscopy.

Organization of central sterilization departments and flows

The architecture of the central sterilization department imposes a segregation of “dirty” and “clean” activities and unidirectional flows of medical devices and staff from the “dirty” area to the “clean” area.

Activities requiring the cleanest environment take place in a controlled atmosphere at a pressure above adjacent activities.

These core principles can be illustrated by the following diagram (for flexible endoscope reprocessing see flexible endoscopy)

9 Office and technical area: the office area regroups the meeting and training rooms, lounges, library, archives, toilets. The Technical area contains supply and filtering functions for Washer-Disinfectors and sterilizers

8 Central and point of use storage area: packaged RMD are stored in controlled conditions (9). In the central storage area a space is reserved for carts The storage area may also be used for urgent dispensing.

7 Sterilizer exit area: Pass-through sterilizers (7) are unloaded, steam sterilized load are given time to cool. Loads are controlled and released (8)

6 Reusable textiles are cleaned and conditioned in a dedicated area to avoid diffusion of cotton fiber dust in clean device reprocessing environment

1 Point of use: RMD are pre-cleaned

2 Changing room

3 Cleaning area: RMDs are received, sorted, manually cleaned (4) and/or automatically cleaned in pass-through washer-disinfectors (5) after ultrasonic pre-cleaning (3) if needed.. A space is reserved for cleaning of transport carts and containers (2)

4 Packaging area: regroups washer-disinfector unloading (5), control & assembly (6) and packaging (7)

5 Sterilization area: Pass-through sterilizers are loaded (7). Single door sterilizers are loaded and unloaded (6)

Point of use processing takes places in the surgical area immediately after use.
The changing room is a prerequisite for any entry in the sterilization department.
The cleaning area regroups all cleaning&disinfection activities including carts and containers. A space is also reserved for prion inactivation (see Reusable Medical Device). The layout of cleaning workstations is optimized to minimize spills and musculoskeletal impacts. Wet areas have non-slip floors. Sufficient space is preserved to load/unload sterilizers. Efficient extraction/ventilation evacuates volatile organic compounds.
The packaging area hosts, washer-disinfector unloading, control & assembly and packaging. This is the most sensitive area with controlled atmosphere to avoid contamination of cleaned devices before packaging. Access is provided via a personal airlock to ensure compliance with hygiene procedures and contain air pressure gradients. Ideally, the packaging area is separated from the sterilization area to allow access to the maintenance engineer without disturbing packaging activities. This partitioning will also provide sound and heat insulation.
The sterilization area includes sterilizer loading (and unloading in case of single door sterilizers). Sufficient space is reserved to load sterilizers. As needed, a special path and space is organized for single door sterilizers (e.g. some low-temperature sterilizers).
The reusable textile area (linen sorting, folding, and packaging) is separated from the medical device flow to avoid contamination of device packaging and sterilization area by cotton fibers.
The central storage and point of use storage are adequately designed and equipped (see storage)
The technical area contains all the infrastructure needed to ensure the proper operation of the sterilization and washer-disinfector It is preferably located close to the production area to reduce the length of ducts, pipes, and wiring. Technical rooms are properly ventilated, non-floodable, regularly maintained, and accessible only to authorized personnel.
The office area includes the offices, meeting rooms, recreation rooms and archives.

The size of the central sterilization department and surfaces allocated to each area are adapted to the level of activity.

Spaces are kept in each area for the storage of cleaning equipment. Rooms are also reserved for waste management.

The sterilization activity generates incoming and outgoing flows of people and materials.

Incoming and outgoing flows of people: sterilization personnel, hospital staff, medical-technical departments, maintenance and qualification operators, staff in charge of sampling and environmental controls, trainees, commercial representative and other type of visitors. The number of visitors allowed to enter activity area is limited. Whenever possible viewing windows allow observation from the outside. Adequate clothing and personal protective equipment is made available for visitors.
Incoming raw material flows : DMR to be sterilized from care departments, operating rooms, or external sources in the case of sub-contracting, new DMR or loaned ancillary equipment, and internal or external supplier deliveries.
Outgoing raw material flows : sterile DMRs (to care departments, operating rooms or external suppliers), defective DMRs sent for repair, returns of loaned sterilized ancillary equipment.

Surfaces

Floors are resistant to pressure and impact, including cart footprints. They are easy to wash and disinfect, and resistant to the various products used, particularly alkaline and non-alkaline disinfectant detergents, NaOH and bleach (where used).

Floors are connected to the walls to facilitate cleaning (grooved baseboard). A continuous floor without joints is preferable. If joints are present, these must be easy to maintain and clean. Floors are fitted with water drainage or suction devices in the washing area. Floor drains must be accessible, removable, cleanable, and disinfectable. They can be non-slip, without interfering with cart handling. Rough floor surfaces that are difficult to disinfect are avoided.

Walls are smooth, crack-free, waterproof, easy to clean or disinfect, and resistant to biocleaning. Protective rails are installed on paths on carts.
Horizontal piping must not be visible. Other piping must not create nooks and crannies that are difficult to clean. Wherever possible, piping and sheathing should not be routed through sterile packaging and exit areas. Otherwise, they should be positioned either at the edge of the zones (corridor) or in drop ceilings, so as to facilitate upkeep and maintenance. Bare wood surfaces are avoided. Stainless steel is difficult to maintain and distracting to the eye, and attention should be paid to the quality of the finish.
Drop ceilings are made of rigid, washable, watertight panels mounted on aluminum support profiles. Spaces above drop ceilings must remain accessible for maintenance of air ducts and piping.

Drop ceilings made of small tiles should be avoided, and larger panels (e.g. 600×1200 mm) are preferred. The recommended ceiling height is 2.80 m. For lower ceilings, precautions should be taken regarding the layout and number of air outlets, and the temperature of the supply air. Ceiling height also has an impact on noise levels (see below).

Written room maintenance procedures describe the personnel in charge, the cleaning equipment, methods and products to be used, frequency of cleaning, disinfection and controls, and records. Maintenance of areas where particulate or microbial contamination is limited is extremely important. Any cleaning equipment likely to resuspend dust is prohibited.

Air quality, pressure, temperature and humidity

Air treatment

Class 8 of international standard ISO 14644-1 is required in packaging area (usually same space as control & assembly, washer- disinfector unloading, sterilizer loading).

Preferably sterilizer unloading, and release areas are also ISO 14644-1 Class 8.

Terminal filtration of supply air is provided by T.H.E. or H.E.P.A. filters.

Pressure

A static overpressure not less than 15 Pascal protects the most sensitive spaces from possible contamination by adjacent areas.

Overpressure

Atmospheric pressure

Packaging areaSterilizer exit area (preferably)

Reusable textile and storage areas,

Changing rooms, office, washing,linen reception and sorting, and technical areas

Air renewal ensures the dilution and elimination of contaminants released into the air by processes and personnel. The air renewal rate ranges from 15 to 20 volumes/hour and is adapted to climatic conditions and to the layout of the premises.
The percentage of fresh air ensuring overpressure is calculated according to the degree of airtightness.

Standard operating procedures specify the organization and frequency of environmental controls (number of particles according to size and microbiological contamination of the air). In the event of non-compliant values, a risk analysis is carried out.

Annual environmental control are recommended. Measures are made when all activity has ceased, after a minimum purification time of 20 min. Microbiological contamination must be monitored during operation, and must be less than 200 cfu/m3.

Particle size equal to or greater than	Max. permissible number of particles/m³ per ISO 14644-1
0.5 µm	3,520,000
1 µm	832,000
5 µm	29,300

The following measurements and checks of the aeraulic system are carried out annually:

filter test and tightness in accordance with SN EN ISO 14644-3 (if HEPA-filters are installed),
measurement of outside air, supply air and exhaust air flows,
calculation of air renewal rate,
direction of air flow at discharge openings and doors between rooms (smoke test),
verification of underpressure in ceiling plenum,
verification of pressure gradient in relation to adjacent rooms.

All premises are air-conditioned and temperature and humidity are controlled. Temperature is maintained between 19° and 25° C, relative humidity between 40% and 75%. Heat input from sterilizers will be corrected by heat treatment of the air and by compensation.

The air-conditioning system is not necessarily supplemented by a rehydration system. This is not useful in all regions, and is a source of technical complications (breakdowns, maintenance, energy costs) and health problems (legionellosis). Rehydration systems should be chosen with care, and steam systems should be preferred over liquid water systems.

Compressed air for drying

The quality of compressed medical air used to treat surgical instruments must be determined and controlled.

ISO 8573-1:2010 specifies compressed air purity classes with regard to the presence of particles, water and oil. According to ISO 7396-1, medical air and motive air for surgical instruments must be filtered to maintain particulate contamination levels below ISO 8573-1 class 2.

Light and noise

Light and noise levels are in accordance with health and safety considerations. Light is adapted to the operations being performed.

Light

Natural lighting is preferred in all areas except storage (see storage).

The lighting environment is adapted to the various activities carried out. The following illuminance values are suggested:

office work: 400 Lux;
loading and unloading of sterilizers: 600 to 800 Lux
visual inspection of RDMs: 750 to 1000 Lux.

Factors to be taken into account include the nature of the lighting itself, the color of floor, wall and ceiling coverings, and the color of work benches or tables.

Lighting equipment must be free from dust-holding projections. Light fittings should be integrated into the drop ceiling, mounted flush and sealed.

Windows are protected to avoid discomfort caused by solar radiation. Glazing must be non-opening, watertight and flush-finished.

Noise

Noise levels must be kept under control. The various machines must be soundproofed.
The ear perceives sounds according to their intensity (decibel) associated with their frequency (hertz). A physiological threshold of 60 dBA (taking into account intensity and frequency) must not be exceeded. Example of measures that can be considered to reduce exposure to noise are

insulating the compressed air blowing ramp in an acoustic box, combined with hearing protection,
isolating sterilizers and washer-disinfectors within technical walls to dampen noise levels,
isolating sterilizers with a rubber base to dampen low-frequency noise,
moving generators and vacuum pumps into technical areas;

Water quality

Water is used at all stages of RMD processing, with or without direct contact with medical devices

Direct contact

Pre-treatment for bath preparation
Manual or automated cleaning in combination with detergents/disinfectants or for thermal disinfection
Final rinse
Sterilization: steam generation in saturated steam EO or LTSF sterilizers,

Without direct contact (examples)

In washer-disinfectors, steam condenser for indirect venting of the chamber of washer disinfector
In sterilizers as a supply to the vacuum pump used to evacuate the chamber

Water is also used for hand washing and cleaning premises.

Water quality in terms of biological quality and compatibility with washing and sterilization equipment is adapted to the different usage and co-defined by applicable local regulations, international standards, and reprocessing equipment and RMD manufacturer’s instruction for use.

Potable water (i.e. safe for human consumption)that enters the hospital network is specified by countries regulations. Quality depends on the supply sources, means of transport and distribution and may vary over time.
Country-specific guidance may define the quality of water to be used for various medical device reprocessing stages.
International standards for sterilizers and washer-disinfectors provide guidance and may define final rinse water quality.

Water that is too hard (i.e. rich in calcium, magnesium and carbonates) reduces the activity of detergents and disinfectants, and creates whitish-scale deposits. Scaling can also affect pipes and machines, potentially leading to clogging and bacterial proliferation.
Water with too high a chlorine content promotes corrosion of instruments. In pipes, this corrosion enriches the water with undesirable chemical elements (iron, copper, zinc) and toxic elements (lead, chromium, cadmium, nickel), leading to changes in the water’s organoleptic parameters (red water, foul odor, etc.). Corrosion is favored by an acid pH. Combined with an acid pH, a high content of halogenated ions (chloride, bromide, iodide) also promotes corrosion. Water with a low mineral content has a high corrosion potential.
Unsuitable water quality can lead to the appearance of stains on the instrumentation, due in particular to the presence of metals, silicates and silica.

Various technologies (filtration, softening, demineralization, reverse osmosis (RO), electrodeionization (EDI), ultrafiltration, distillation are available to adapt water quality to various needs.

Filtration separates and traps particules and microorganisms from incoming water. The level of filtration (size of particles retained by the filter) is adapted to need. Pre-filtering is required to avoid clogging in downstream filters. All filtration systems concentrate microbial pollution. The risk of breakage becomes higher when pressure increases upstream of the filter due to clogging. It is therefore essential to ensure that all replacement, servicing, maintenance and analytical control operations are carried out in accordance with the manufacturer’s defined and documented procedures.

Softening is intended to reduce water hardness and limit scaling. Softened water can be used for cleaning and initial rinsing, to feed a reverse osmosis unit, to produce steam for autoclaves or water for the thermal disinfection cycle of washer-disinfectors.
Softeners must be carefully and regularly maintained according to suppliers’ recommendations and the volume and initial hardness of the treated water. Compatibility with the disinfectant must be indicated by the manufacturer. Monitoring of microbiological potability criteria (absence of pyocyanic bacteria) is recommended at least once every six months, or more frequently if needed.

Deionization (DI) or demineralization reduces the content of ionic species and dissolved inorganic substances by a physical, chemical or biological process. Conductivity (i.e. measure of the capability of water to pass electrical flow) decreases in proportion to the removal of ions. Low conductivity indicates that there has been efficient removal of ions.

Poor maintenance of the DI system leads to increased levels of microorganisms and endotoxin in the water. Additional treatment steps can be needed for specific applications after DI to ensure the microbial quality of the treated water (e.g. filtration treatments that remove pyrogens, submicron filters that remove microorganisms, ultrafilters).

Reverse osmosis (RO) is a chemical and antimicrobial treatment. The water to be treated is passed over a semi-permeable membrane. Reverse osmosis retains most of the compounds present in water (particles, colloids, organic contaminant ions, including bacterial endotoxins and microorganisms). Reverse osmosis achieves chloride ion levels of less than 2 mg/l and SiO2 silica levels of less than 1 mg/l. The conductivity of reverse osmosis water is less than 15 µS/cm at 25°C. Its pH is between 5 and 7. RO water hence is highly corrosive. RO water can be used for final rinsing, thermal disinfection and to power the sterilizer’s steam generator.
In order to avoid saturating the osmosis membrane, pre-treatment must be carried out upstream, generally with several stages of filtration, dechlorination on activated carbon if necessary, and softening. RO systems must be carefully and regularly maintained in accordance with the supplier’s recommendations. Membrane performance can be measured continuously (resistivity meter) or at regular intervals. It is disinfected at the frequency recommended by the manufacturer.

Despite high filtration efficiency with the RO process, minimal leakage of micro-organisms, particularly viruses, may occur, and biofilms may colonize pipes and tanks downstream of the treatment.

Storage is essential to adapt the RO water production to consumption. Storage tanks are a potential source of contamination for reverse osmosis water. To limit contamination, it is preferable to

store as little water as possible;
avoid stagnation in the circuits and reservoir, by using a loop system to ensure continuous circulation and eliminate dead legs;
not exceed a temperature of 25°C;
use a tank that can be completely emptied, easily washed and disinfected.

Electrodeionization (EDI) removes ions, silica and organics from the feedwater and is often used as a polisher after RO to reduce conductivity.

Ultrafiltration operates by size exclusion at the molecular level and is capable of removing organics, microorganisms and endotoxins. Ultrafiltration be situated in the early stages of the treatment system to remove organics or in the final stages often post RO to act as a polisher.

Distillation uses the vaporization and condensation of water to remove dissolved and suspended substances. Distillation effectively removes microorganisms, endotoxins, organic compounds and colloids. It requires more energy to operate than RO or DI and installation is more costly. Production is slow and a storage tank is needed. Measures are needed to prevent scaling or coating with colloidal material.

In practice, device reprocessing requirements for water can be summarized as follows:

Precleaning, manual cleaning, intermediary rinsing: potable water according to applicable local regulation. The water may be softened if the mains water is too hard.
Automated cleaning: according to washer-disinfector manufacturer’s recommendations, applicable international standards, regulation or guidelines: softened, demineralized or RO water.
Automated rinsing and thermal disinfection: according to washer-disinfector manufacturer’s recommendations and applicable international standards, regulation or guidelines: soften, demineralized or RO water. Microbial quality is also specified by some applicable international standards, regulation or guidelines

	ISO 15883-4: 2018	AAMI ST 108 2023	HTM 01-01* HTM 01-06**
Total viable count	≤ 10 CFU/100 ml	<10 CFU/ml	≤100 CFU/100 ml* ≤10 CFU/100 ml**
Bacterial endotoxin	In accordance with WD IFU.	<10 EU/ml	≤ 0,25 EU/ml* ≤ 30 EU/ml **
Pseudomonas aeruginosa	Not detected/100 ml	Not specified	Not detected/100 ml**
(Atypical) Mycobacterium sp.	Not detected/100 ml	Not specified	Not detected/100 ml**
SO 15883-4:2018Washer-disinfectorsPart 4: Requirements and tests for washer-disinfectors employing chemical disinfection for thermolabile endoscopes HTM 01-01 (UK): Management and decontamination of surgical instruments (medical devices) used in acute care HTM 01-06 (UK): Decontamination of flexible endoscopes. ANSI/AAMI ST108-2023 (USA): Water for the processing of medical devices

Final rinsing water for manual disinfection of critical flexible endoscope: sterile water (see flexible endoscopy)
Steam generation for saturated steam and low temperature steam formaldehyde sterilizers: demineralized water or RO water according to the recommendations in standard EN 285, EN 13060 and EN 14180. EN 1422 for Ethylene oxide indicates that potable water is considered the minimum requirement for steam used for humification of load.

Determinant	Water for moist heat sterilization EN 285, EN 13060, EN 14180 (informative annex).
Residue on evaporation	≤ 10 mg / L
Silicate (SiO2)	≤ 1 mg / L
Iron	≤ 0,2 mg / L
Cadmium ^a)	≤ 0,005 mg/ L
Lead ^a)	≤ 0,05 mg / L
Rest of heavy metals except iron, cadmium, leadb	≤ 0,1 mg / L
Chloride ^b)	≤ 0,5 mg / L for large steam sterilizers and LTSF ≤ 0,2 mg / L for small steam sterilizers
Phosphate	≤ 0,5 mg / L
Conductivité (at 20 °C) ^c)	≤ 5 μS / cm for large steam sterilizers and LTSF ≤ 15 μS / cm for large steam sterilizers
pH (20°C) value	5 à 7,5
Appearance	Colourless, clean, without sediment
Water hardness (Σ Ions of alkaline earth)	≤ 0,02 mmol / L
a) The limiting values meet the requirements for potable water. b) European Pharmacopoeia (EP), Monograph 8, Purified Water, Test method V.3.2.8. c) Maximal chloride concentration in feed water influences corrosion in combination with high temperatures.

autoclave vacuum pump and cooling circuit: Manufacturers recommend softened water to reduce scaling. scaling due to excessively hard water can affect equipment and pipes, leading to loss of efficiency, clogging and bacterial proliferation

Facilities, air & water and quality management

Facilities are designed and maintained in accordance with needs and quality management principles:

Equipment is installed in accordance with manufacturers recommendations. Instructions for use and certificates are available. When needed, equipments is qualified according to process validation principles.
Updated standards operating procedures (SOP) are available for cleaning of facilities and maintenance of equipments (air and water treatment and others).
Routine controls (for air and water treatment systems, light, noise, surfaces and other equipments) are specified and in accordance with applicable regulation and international standards.
Occupational health & safety measures ensure the confort and safety of operators (temperature and humidity levels, light, noise, wet area, ergonomics of workstation, exposure to liquid and vaporized chemicals, aerosols, injuries by potentially contaminated RMD).
Waste is collected and discarded according to local waste management rules.
Training on SOP, routine controls, occupational health & safety and waste management take place and knowledge are periodically controlled.
Traceability is operational.

WFHSS recommendations for facilities air and water

Location of devices reprocessing facilities are defined by need and hospital strategy and adapted in size and equipement to the type and level of activity. Sterilization is preferably centralized. Disinfection is at point of use or centralized. See also flexible endoscopy

The architecture of the central sterilization department imposes a segregation of “dirty” and “clean” activities and unidirectional flows of medical devices and persons from the “dirty” area to the “clean” area.

Facilities and equipments are cleaned, maintained and controlled in accordance with standard operating procedure and follow applicable guidelines or regulation.

Air quality depends on the type of activity. Overpressure is maintained in the most sensitive area to avoid contamination from adjacent areas.

Water quality is adapted to need and in accordance with applicable regulation, international standards and guidelines.

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