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March 18, 2020
Written by Robert E. Sheriff, CIH, CSP
How to Achieve Good Indoor Air Quality in Operating Rooms
There are two primary objectives in achieving acceptable air quality in the operating room: (1) control of anesthetic gases for the benefit of operating room staff, and (2) infection control for the benefit of the patient.
Control of Anesthetic Gases
Supply and scavenging systems, as well as general ventilation in Operating Rooms and Surgical Suites, must be functioning optimally for the surgical staff to be protected from exposure to anesthetic gases.
OSHA has established guidelines for the protection of operating room personnel but does not have Permissible Exposure Limits (PELs) for the most common anesthetic gases, nitrous oxide (N2O) and the halogenated gases (Enflurane, Halothane, Isoflurane, Desflurane, and Sevoflurane). Monitoring for these anesthetic gases is not complicated. Diffusion badges or small battery-powered air samplers can be attached to OR occupants and worn while performing their duties. Direct reading measurements can also be made using an infrared spectrophotometer as a leak detector for the gas supply system or effective operation of the waste gas scavenging system. Thus the exposure to anesthetic gases can be monitored regularly and should be part of the Hospital/Health Care Institution IAQ Program. Usually, this inspection/testing should be performed every 6 months (see Table 1)
Air quality testing/sampling during surgical procedures do not allow for an industrial hygienist/air quality specialist to be in the OR during surgeries but this can often be overcome by using battery-powered samplers and air/gas collection bags that can be retrieved and read by the IR Spec Instrument, as well as the diffusion badges for the halogenated gases.
There are recommended exposure levels for each of the anesthetic gases, either recommended by other agencies/groups or standards set in other countries:
Leak Detection
Leak detection of anesthetic machines is a critical element of Operating Room Air Quality Control, not only for the anesthetic gases but also for oxygen. Oxygen control is actually a third element in OR Air Quality Control, primarily as a fire protection measure. Weak points in the anesthetic equipment supplying oxygen can leak, elevating levels and greatly increasing the risk of fire. A direct reading oxygen meter can readily detect leaks or oxygen levels above the OSHA recommended safety level of 22% oxygen. OSHA states that oxygen levels must be maintained between 19.5% and 23.5%.
The recommended rate of air exchange in an OR is 15 air changes per hour (15 ACPR) and at least three air changes must be of fresh air and no re-circulation of air streams carrying waste anesthetic gases.
International Clean Room Standards
ISO/TC209 has proposed ten (10) documents which will make up the Clean Room standards. These documents are in their final voting stages and can be legally used in trade. The tables and sections below outline the first seven of these documents in order.
ISO14464-1 Classification of Air Cleanliness
Cleanliness class designations and quantity have changed from FS209E (see Table 1). Along with the obvious change to the metric measure of air volume, ISO 14644-1 adds three additional classes. (It should be noted that the standard operating room is not likely to be able to achieve Class 1 to 4 levels of cleanliness.)
The effectiveness of scavenging systems can be determined through the use of smoke tubes to detect suction leaks or by measuring the airborne levels of anesthetic gases when the anesthetic machines are charged and the scavenging system is operating. A direct reading instrument such as an IR Spectrophotometer is ideal. There are also other direct instruments that are smaller than an IR and easy to use.
Another important element of control of anesthetic gases is in post-op, usually referred to as Post-Anesthesia Care Units (PACU) where exhaling by the patient accounts for the uncontrolled waste gases.
ISO-14644-4 Clean Room Design and Construction
This document will be a primer on the design and construction of Clean Rooms. It will cover all aspects of the process from design development to start-up and commissioning.
ISO-14644-5 Clean Room Operations
This document will be an introduction to Clean Room Operation. It will cover all aspects of the operation of a Clean Room including entry and exit procedures for equipment and personnel, education and training, Clean Room apparel, and facility issues such as maintenance, housekeeping, monitoring, system failure, etc.
ISO-14644-6 Terms, Definitions, and Units
This document will provide a consistent reference for all terms, definitions, and units discussed across all ISO.
The effectiveness of scavenging systems can be determined through the use of smoke tubes to detect suction leaks or by measuring the airborne levels of anesthetic gases when the anesthetic machines are charged and the scavenging system is operating.
Another important element of control of anesthetic gases is in post-op, usually referred to as Post-Anesthesia Care Units (PACU) where exhaling by the patient accounts for the uncontrolled waste gases.
Infection Control
Infection control in operating rooms is not generally considered an element of air quality since numerous studies have shown that most infections are from the patient themselves or actions/practices of the surgical staff.
Examples are pre-entry disinfection and scrubbing, clothing, movement in and out of the OR during surgery, keeping hands always above the table height, sanitizing equipment and supplies entering the OR, etc.
Infection control is maintained in air quality by achieving and maintaining airborne particulate control through air filtration and satisfying the Clean Room Particulate Limits set in ISO 14644. For operating rooms, that is Category 4 which is 10,000 particle/per cubic meter of air of 0.1 microns or larger (Table ISO 14644-1). (Note: the ISO 14644 Standard has replaced Federal Standard 209E).
In any event, airborne particles can be measured in real-time using direct reading particle counters that can also measure particle size distributions.
OSHA recommends testing of operating rooms and surgical suites in hospitals, out-patient surgical suites, dental offices, and veterinary ORs every six months.
ISO also has developed standards for the frequency of testing of various parts of the control system. See below.
For more information about Air Quality in Operating Rooms and Surgical Suites and a free proposal, contact Atlantic Environmental at 973-366-4660, email us at info@atlenv.com or use our easy website online form.
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