Mercury Lamps and UVC LEDs
Low-pressure mercury lamps that emit ultraviolet light in the shortest wavelength range (UVC) are an effective technology used for disinfection at room temperature. Another technology uses light-emitting diodes (LEDs) to give off UVC. While both methods have a proven ability to penetrate cell walls and deactivate microbial DNA, mercury lamps provide several advantages in a healthcare setting.
How Mercury Lamps Work
This technology uses mercury in the bulb of a low-pressure fluorescent-type lamp to convert electricity to light waves. When activated by an electric current inside a glass tube, elemental mercury naturally emits a large amount of ultraviolet light energy at the 254 nm wavelength – right within the germ-killing range.
Unfortunately, mercury is a poisonous substance that requires careful handling and disposal to prevent harm to humans and to the environment. These hazards can be mitigated with good design and handling protocols. For example, UVC fluorescent lamps are made of quartz glass to enable the short wavelength to pass through and these quartz tubes are more difficult to break than standard fluorescent lamp tubes.
Because of the inherent dangers of mercury, most mercury lamps are rapidly being phased out. However, exemptions have been made. For example, in the EU an exemption has been approved through at least 2027 for certain lamps not exceeding 15 mg of mercury. This exemption is limited to low pressure discharge lamps that are not phosphor-coated and that emit light in the ultraviolet range. [i]
The Role of Mercury Lamps in Healthcare Disinfection
The reason for the European Commission exemption is that no substitution for the mercury lamp by a substance of comparable performance is currently technically practicable. Preventing healthcare-associated infections through disinfection with UVC is one specific example where mercury lamps show many advantages over current LED UVC technology.
Mercury Lamps vs UVC LEDs in Healthcare
Although UVC LEDs are becoming more available, current LED technology has disadvantages that affect their utility in healthcare disinfection. For example, the UVC dose output of LEDs compared with fluorescent lamps is very low, especially within short disinfection time periods.
Unlike other types of LEDs, the ones that emit light in the UVC range are less energy efficient and require substantially more power than fluorescent lamps. These also produce a large amount of heat that must be dissipated via cooling structures, making LED disinfection devices bulkier and less compact.
The Robustness and Reliability of Mercury Lamps in Healthcare
Mercury lamp technology has been used and perfected for decades. As a result, the technology has proven reliable while the cost of manufacturing the lamps is relatively low.
Because of their novelty and current small-scale application, UVC LEDs can cost up to $40 each. To reach a similar UVC disinfection capacity as the mercury lamp-based UV Smart D25, for example, an LED device would need to include 400 LEDs. At this price point, LED UVC devices are unaffordable for healthcare providers.
Mercury Lamps in Healthcare: A Case Study
Mercury lamp-based devices have now proven to benefit the disinfection operation of healthcare facilities. For example, in a study at the ETZ Hospital in Tilburg, The Netherlands, the disinfection process for channel-less ENT-endoscopes was improved with the addition of a UV Smart D60.
This implementation created a shift in the hospital. Previously, disinfection of these devices was done in the central sterilization departments. With the D60, disinfection can take place within the ENT department itself, rather than sending the endoscopes to the central cleaning area.
This adjustment means less transport time and fewer logistical issues, making the turnaround much shorter so that more patients can be seen.
Also, where endoscopes were often broken during transport to and from the department, no breakage has occurred with the implementation of the D60. Meanwhile, inventory has been reduced from 35 endoscopes to 25 endoscopes, which has saved the hospital money.
Advantages of Mercury Lamps in Healthcare Disinfection
While many countries and healthcare facilities have begun to reject products which use or contain mercury, the balance of risk and benefit should be carefully considered when comparing mercury lamps with other UVC sources, such as LEDs.
For certain healthcare applications, mercury lamps have proven to be a better technology for disinfection of medical devices. At UV Smart, we consider that the benefits of improved overall efficiency and lower costs outweigh the risks when proper safety measures are taken.
With UV Smart disinfection products, healthcare facilities can better serve their patients with faster service and lower costs, while maintaining safety and preventing the spread of infectious diseases.