Consider the importance of what happens in the nation’s laboratories. From the discovery of life-saving antibiotics in a university research lab, to identifying which virus is causing a patient’s illness in a hospital lab, to developing new materials that revolutionize consumer products in an industrial lab, laboratory work benefits people in numerous ways.
Yet, as important as lab discoveries are, the first priority in designing and operating a lab is not the results the lab will produce. The highest priority is ensuring lab worker safety, since they often work with hazardous materials.
In this article I’ll discuss the plethora of airborne hazards lab workers face, and how advanced air flow control technologies can reduce the dangers, while lowering maintenance costs and conserving energy—in both positive and negative pressure environments.
Injury and Death Carried in the Air
Lab workers can be exposed to any number of hazards in the air, with adverse effects ranging from mild respiratory irritation to severe injury, and even death, depending on the agent and level of exposure.
The University of Texas at Austin’s Environmental Health & Safety Department has summarized the range of airborne dangers that might be present in a lab. First are several types of compressed gases:
• Poisonous (chlorine, carbon monoxide)
• Reactive (ammonia, boron trichloride)
• Flammable (acetylene, ethylene)
• Inert (nitrogen, argon).
The university notes that while the first three gas types are of “particular concern,” even the inert compressed gases are dangerous, as they can displace oxygen from confined spaces, leading to asphyxia. In addition to other harmful properties a gas might have, any cryogenic (ultra-cooled) gas presents an inhalation hazard as it can instantly freeze a person’s upper airway.
Beyond hazardous gases, other potential airborne dangers in labs—especially in healthcare and/or bio-medicine—include toxic fumes from pharmaceuticals (such as antineoplastic chemotherapy drugs for cancer); pathogens such as viruses and bacteria; and particular solvents used in hospitals for staining and processing tissues in pathology labs to help determine a proper diagnosis for a patient.
Keeping Lab Air Safe
More than 500,000 people in the U.S. work in labs, according to OSHA. For these workers, engineering controls provide the first line of defense against potential airborne hazards. OSHA notes, “These types of controls are preferred over all others because they make permanent changes that reduce exposure to hazards and do not rely on worker behavior.” I like to think of the engineering controls as being like passive restraint systems in a car—they’re built-in to enhance safety.
Engineering controls for keeping lab air safe must ensure adequate ventilation/air exchange rates and filter airborne contaminants, while maintaining appropriate pressure relationships with spaces adjoining the lab. For example, the airflow controls must provide positive pressure in lab spaces that must remain sterile, or negative pressure in order to keep pathogens contained.
Historically, ventilation systems in labs have relied on traditional variable air volume (VAV) terminal units/boxes. These calibrated air dampers manage airflows into a space, and are common throughout commercial and institutional buildings. Yet, for laboratories and other critical environments, I much prefer high-performance venturi valves, because VAV boxes and similar units are much less efficient and require maintenance and cleaning.
In contrast, venturi valves provide labs with more accurate airflow control, which allows them to safely maintain their pressurized spaces while reducing their energy costs. Venturi valves provide high accuracy airflow control due to:
• Volumetric offset, with the supply valve tracking the exhaust valve to maintain a desired offset, guaranteeing directional airflow.
• Factory characterized flow metering technology that provides higher turn-downs to achieve a number of stable, accurate room states.
• High response speed, which cannot be matched by valves requiring flow measurement (e.g., VAV boxes and other alternatives) due to inherent signal latency between the flow sensor, controller and actuator.
• Mechanical pressure independence that maintains flow, even with constant changes in static pressure, so that a stable, air delivery rate is not compromised.
Higher turndown ratios mean the device has a wider range over which it can accurately provide the correct airflow. With this improved accuracy, labs can better manage ventilation and maintain air pressure relationships for worker safety and research integrity, regardless of room state (occupied, unoccupied, or purge condition).
The room-level air handling provided by systems with venturi valves are an important complement to fume hoods. In essence, the fume hoods vacate hazardous gases from a contained work space, while the room level systems exhaust those gases to the outside, while also ensuring appropriate ventilation throughout the lab.
Bridging the Disconnect Gap
As IH professionals know, protecting workers should be Job One in any workplace. This is especially true in labs, where workers can be exposed to airborne hazards ranging from toxic dust and smoke to poisonous fumes and deadly microbiological agents. The building’s engineering controls are the first line of defense against these dangers, and modern air handling systems provide safe air while saving energy.
One issue for IH pros to keep in mind when working on lab air safety is there sometimes is a disconnect between the air balancing engineers and the NSF certifiers regarding specs and safety. As a key advocate for worker safety, industrial hygienists can bridge that gap to ensure appropriate airflow controls for the space.
John Ostojic is a senior industrial hygienist for Artec Environmental, a provider of medical gas and environmental products and services. A graduate of Purdue University with a BS in industrial hygiene, Ostojic has 17 years of experience in the field.