UV decontamination lighting has been incorporated into biosafety cabinets for decades, and persistently over-relied on for decades in cell culture work. Green labs are removing UV lamps from biosafety hoods to eliminate risks and save energy. It’s a simple action that overcomes energy waste in the right setting.
The conventional thinking with biosafety cabinets is to wipe down the interior, close the hood sash, turn off the air blower, and decontaminate with UV light at the end of the day. Good sterile technique is a must. Whether I was developing monoclonal antibodies with cultured hybridomas or carrying out RNA interference experiments with lymphocytes, the loss of cells to mycoplasma or yeast was unthinkable. I admit I routinely left UV lights on overnight in many labs I worked in. I thought I was protecting our work. However, wiping down the inside surfaces of the tissue culture hood more thoroughly - perhaps even the cooling coils of refrigerated centrifuges which might have been spewing microbes into room air - would have been more vigilant. Contamination was always on my mind, but I never considered the effectiveness of UV light decontamination. For example, I had no clue that just because a UV bulb still lit up, that didn’t mean that it was still emitting effective radiation. UV just seemed foolproof.
The over-reliance on UV light decontamination was called out in the literature years ago and countered with the recognition that it was needed in some settings but leaving it on overnight was massive overkill. The benefits and risks of UV were openly acknowledged which could have prompted widespread change - the thing is old habits die hard.
The overuse of UV isn’t connected directly enough with negative experimental outcomes to drive change. There is good evidence supporting UV light inactivation with many microorganisms. More than 80% of biological safety cabinets manufactured in the USA have UV-C lighting installed. Newer hoods can have preset timers for UV Lighting, switches interlocked with shut sashes, and displays for UV bulb lifetime built in, but in more common setups, it’s tricky to prevent overuse.
There are many Biosafety Cabinets out there with 30-watt UV lamps left on for 12 hours overnight unnecessarily consuming ~0.36 kWh of energy. Based on metering tips for Class II Biosafety Cabinets from the University of College London, a world leader in sustainable labs, a cabinet can consume 0.25 kW/hr. To keep it simple, you can think of a UV bulb run overnight as consuming as much energy as leaving the laminar hood running at full power for an extra hour every day with no one using it. The overuse of high energy-consuming mercury bulbs is counterproductive to carbon-neutral ambitions.
Green labs are calling out inappropriate use of UV, pointing out energy waste, and taking action
There are multiple environmental benefits to removing UV lightbulbs from tissue culture hoods. First, UV lights in biosafety cabinets usually contain toxic mercury. Exposure to UV light itself is an eye and skin safety risk for the people working in the laboratories. UV lights can provide a false sense of sterility. Contaminants will persist due to micro shadows inside the cabinet. From a sustainability standpoint, the energy consumed by UV lights is several times greater than standard room LED lights.
Green lab teams are selecting lab spaces to take this action. Tissue culture teaching labs are a great place to instill good sterile technique, thorough manual wipe-down skills, and environmental stewardship. Students care about their environmental footprint and will carry best practices into the future. At a recent Cambridge Sustainable Labs group meeting, I learned that Harvard University was doing just that. Similarly, a biopharma had removed UV lamps in certain BSCs to reduce its carbon footprint. If you’re interested in which types of life science work preclude this action, you can read my post Why Do Most New Biosafety Cabinets Still Have UV Lights?
I loved hearing about progress on this issue. After all, you can’t leave the UV lamp on when there is no bulb!
