D. JEFF BURTON, MS, PE, FAIHA (former CIH and CSP, VS), is an industrial hygiene engineer with broad experience in ventilation used for emission and exposure control. He is an adjunct faculty member at the Rocky Mountain Center for Occupational and Environmental Health at the University of Utah in Salt Lake City. Editor’s note: A version of this article originally appeared on the SynergistNOW blog on June 15, 2021. Send feedback to The Synergist.
The New Laboratory Ventilation Standard
The recently revised ANSI/ASSP Z9.5 standard on laboratory ventilation is now available from the American National Standards Institute and the American Society of Safety Professionals. The update—the first for this standard since 2012, when AIHA was the ANSI Z9 secretariat—was directed by James Coogan, chair of the Z9.5 subcommittee, and completed by sixteen subcommittee members who are competent in lab ventilation. I was honored to be one of those members. Broadly defined, industrial ventilation is a method of controlling the environment with airflow and is used to minimize employee exposures to hazardous chemicals and biological agents, mainly by removing or reducing air contaminants to safe levels of exposure. ANSI Z9 standards specify performance of ventilation equipment so it can provide safe and healthy workplaces. They are developed through cooperative efforts of experts and provide a consensus at the time when the standards are published. COVERAGE OF ANSI Z9.5-2022 The updated standard has over 150 pages, consists of ten main sections and five helpful appendices, and provides over 450 requirements and good practices for labs to follow. It covers all types of laboratory-related ventilation topics including management, system design, construction, hood airflow requirements, airflow testing and monitoring, special requirements for unique lab hoods (such as gloveboxes, ductless hoods, and perchloric acid hoods), airflow management, supply air systems, exhaust air systems, ductwork, recirculation of exhaust air, commissioning of lab ventilation systems, reporting, training and work practices, maintenance, emergency responses, air cleaning and filtration, and appropriate exhaust air pollution control equipment. Appendix 4 provides an audit tool to help users determine whether they are in compliance with recommended standard practices. Following is a sampling of these practices, numbered as they appear in the new standard: •3.1. Management has established a Laboratory Ventilation Management Plan (LVMP) to help ensure proper design, selection, operation, use, and maintenance of laboratory ventilation equipment.
•3.2. In each operation using laboratory ventilation systems, management has designated a “Responsible Person.” (Note: this individual is often an OEHS professional.)
•3.3. Laboratory management has developed a Chemical Hygiene Plan (CHP) in accordance with the OSHA standard on occupational exposure to hazardous chemicals in laboratories (29 CFR 1910.1450) and incorporated it into the LVMP.
•3.3. The design and operation of laboratory and exposure control ventilation systems limit worker exposures to safe concentrations.
•3.4. There is a process for systematically assessing the potential for hazardous chemical exposures, which applies to all spaces and devices where a potential exists for overexposure to airborne hazards.
•3.7. Adequate laboratory fume hoods, special purpose hoods, or other engineering controls are used when there is a possibility of employee overexposure to airborne contaminants generated by a laboratory activity.
•3.9. Complete and permanent records are maintained for each laboratory ventilation system as part of the written LVMP.
The updated standard has over 150 pages, consists of ten main sections and five helpful appendices, and provides over 450 requirements and good practices for labs to follow.
•4.3.1. The average face velocity of a lab hood is sufficient to capture and contain the hazardous chemical emissions generated within the hood, for which the hood was selected. An adequate face velocity is not the only criterion to achieve acceptable performance and is not used as the only performance indicator. Complete hood containment is verified as appropriate for the hazard being controlled using multiple testing approaches (for example, visual methods such as the release of smoke to determine air movement, face velocity testing, exposure assessments, tracer gas containment testing, and so on).
•4.3.2. The following considerations are taken into account (where applicable) as part of the risk assessment when setting a minimum hood airflow rate: containment of effluents released into hood; potential for fire or explosion within the hood and exhaust system; proper removal of contaminants from the hood and exhaust system; corrosive atmosphere in the hood; resulting flow rates, velocities and static pressure needs throughout the duct exhaust system; effect of airflow rates on room pressurization and air movement in the space; and the operating range and accuracy of the airflow control system.
•4.3.3. All hoods are equipped with a flow indicator, flow alarm, or face velocity alarm indicator to alert users to improper exhaust flow. The flow-measuring device is capable of indicating that the airflow is in the desired range and of providing alarms when the flow is high or low by up to 20 percent.
•5.1.7. The air or gas exhausted from a hood is cleaned and discharged to the atmosphere in accordance with the general provisions of this standard and any pertinent environmental regulations.
•6.1.1. Laboratory designers consider potential effects on safety and health when establishing floor plans and spatial layout. Laboratory chemical hoods are located so their performance is not adversely affected by cross drafts.
•6.4.4. Each fan serving a laboratory exhaust system or used to exhaust an individual piece of laboratory equipment—for example, a chemical hood, biosafety cabinet, or chemical storage unit—is adequately sized to provide the necessary amount of exhaust airflow in conjunction with the size, amount, and configuration of the connecting ductwork.
•7.1.1. All newly installed, renovated, or modified lab ventilation systems are commissioned to verify proper performance prior to use by laboratory personnel. The commissioning process starts during design of the systems and extends through construction to verify that the systems conform as specified by its design and the requirements of the Z9.5 standard.
• All fume hoods are tested following installation (at the “as installed” conditions) and before actual use with potential airborne hazards.
•7.3.3. The operations of mechanical system components are tested periodically to confirm their effectiveness. These routine tests are conducted at least annually or more often as necessary to verify proper operation and validate the information reported to the Building Automation Systems (BAS) and other monitoring and alarm systems. The routine lab environment tests are coordinated with preventive maintenance activities to help improve reliability of system performance.
•7.4. All test instrumentation utilized for the tests prescribed throughout Section 7 is in good working order, is factory calibrated within one year of the date of use and as specified by a relevant standard such as ASHRAE 110 “Method of Testing Performance of Laboratory Fume Hoods” or in accordance with manufacturers’ specifications.
•8.3. Hood users are trained in its proper operation prior to use.
•9.0. Inspection and maintenance practices follow a Preventive Maintenance (PM) Program developed by the user.
•10.2. Air-cleaning systems for laboratory exhaust, where required, are designed, specified or approved by a Responsible Person to ensure that they will meet the performance criteria necessary for regulatory compliance.
GUIDING OUR PRACTICE ANSI Z9 standards are important to OEHS professionals because they can promote and guide our practices. A list of ten current Z9 standards appears in the sidebar. For more information about these standards, contact Lauren Bauerschmidt, ASSP’s manager of standards development.
Current ANSI/ASSP Z9 Ventilation Standards
ANSI/ASSP ventilation standards cover a wide range of topics. They are intended for use by employers, OEHS professionals, facility engineers, and maintenance personnel to protect health and safety by controlling airborne contaminants. The following standards are managed by the ANSI Z9 committee:
Z9.1-2016, Ventilation and Control of Airborne Contaminants During Open-Surface Tank Operations
Z9.2-2018, Fundamentals Governing the Design and Operation of Local Exhaust Ventilation Systems
Z9.3-2017, Spray Finishing Operations: Safety Code for Design, Construction and Ventilation
Z9.4-2011 (R2021), Abrasive-Blasting Operations—Ventilation and Safe Practices for Fixed Location Enclosures

Z9.5-2022, Laboratory Ventilation
Z9.6-2018, Systems for Grinding, Polishing and Buffing
Z9.9-2021, Portable Ventilation Systems
Z9.10-2017, Fundamentals Governing the Design and Operation of Dilution Ventilation Systems in Industrial Occupancies
Z9.11-2016, Laboratory Decommissioning
Z9.14-2020, Testing and Performance-Verification Methodologies for Biosafety Level 3 (BSL-3) and Animal Biosafety Level 3 (ABSL-3) Ventilation Systems
AIHA: Lab Ventilation Guidebook, 2nd ed. (2012).
American National Standards Institute: “Z9 Ventilation System Standards.”
American Society of Safety Professionals: “Ventilation Systems.”