The Impact and Efficacy of Germicidal Light Bulbs and Fluorescent Tubes

1. Introduction to Germicidal Light Bulbs and Fluorescent Tubes

Ultraviolet (UV) radiation has been used to kill and inactivate microorganisms for many years. Artificial light has also been used historically in a number of applications for air, surface, and water disinfection. A variety of UV sources have been developed for this purpose based around the mercury low-pressure discharge lamps, including fluorescent tubes. Light-emitting diodes (LEDs) have provided a new source for development, with manufacturers creating materials to produce UV radiation and giving the potential for more mobile devices. These sources emit four different kinds of UV light, falling into two categories: short-wavelength UVC and far-wavelength UVA.

It is the lower energy UVC that offers the most germicidal properties, a result of being absorbed the strongest by the RNA and DNA of cells, damaging the ability to replicate before cell processes are affected. UVC fluorescents have been the most widely used due to their ability to be produced from low intensity and minimal maintenance, unlike those such as pulsed xenon and UVC LEDs. Although data for different UVC light sources are not always compatible, a key comparison shows more rapid disinfection with fluorescent tubes to be executed at larger distances with increased power, owing to the collimated light. In this present day, ultraviolet light is growing in applications that will now add no harm to public health or the environment. This includes healthcare, food safety, and general sanitation, with a large increase in the number of locations housing UVGI air handling systems. The ultraviolet spectrum is divided into four standard divisions.

2. Mechanism of Action and Types of Germicidal Light Bulbs

Germicidal light bulbs, a type of tubular bulb produced either as a bulb or a fluorescent tube, are an effective disinfection method that uses cost-effective ultraviolet (UV) radiation. Most microorganisms are sensitive to ultraviolet radiation between 100 and 280 nm in wavelength, but few are resistant to the shorter-wavelength rays, which can damage microorganism nucleic acids. Germicidal lamps work via the generation of UV radiation, which disrupts the genetic material, deactivating virus replication, bacteria multiplication, and fungi. The evolution of germicidal lamps has been long and involves technologies due to physics and light bulb construction.

Two types of germicidal light bulbs currently available are mercury vapor lamps and low-pressure mercury lamps. Notable differences between the two lie in output intensity, the lifetime of the emitted UV-C light, and efficiency. These fluorescent tubes and bulbs are grouped by functions, such as traditional and modern use. In activating light, there are 'standard' or 'all-purpose' germicidal light bulbs, with a lifespan of 2 years, that can be used around the home, in hospitals, and in laboratories as they have satisfying efficiency; there are also 'high output' germicidal light bulbs with greater output, which are useful for air and water disinfection. Tubes with additional coating are also available; for instance, triple-bore tubing may have a phosphor coating directly mixed with glass that shifts emitted light toward a longer wavelength. Bulbs can be made with different diameters and a choice of base type. It is important to choose the right germicidal lamp type for the application to be disinfected.

3. Applications and Benefits in Various Settings

Germicidal light bulbs and fluorescent tubes could benefit a wide range of applications across various settings, especially in healthcare. Germicidal bulbs are used in doctors’ offices, dentist offices, restrooms, waiting rooms, and lobbies. Hospitals and healthcare centers are learning that ultraviolet and germicidal lighting can be an effective means of controlling infection. They are, however, very useful in food production and preservation, especially by the facilities that produce pre-packaged and pre-made salads. These products have been shown to be more prone to the transmission of various germs, such as salmonella and E. coli. Schools and daycare centers are being proactive in preventing flu by using lighting systems in their facilities that inactivate viruses that can cause flu. Using germicidal lighting in these facilities reduces absenteeism. The leaders of many educational institutions are advocating affordable solutions to improve indoor air quality as part of the integrated design planning process. This includes the use of ultraviolet light and germicidal technology to deactivate bacteria, viruses, and protozoa, which would increase security and decrease healthcare and maintenance costs.

A UVC air disinfection system was installed at a regional infant and toddler facility to prevent infections by respiratory viruses, which are prevalent in summer and decline in winter. As a response to the public IPC’s need for UVC air disinfection, a passive radiative system (8 watts/bulb) was installed in the general area. Further, the facility AC and heater unit’s UVC source bulbs are shut down and not installed to avoid limiting the source fixtures design. These disinfection systems are dated with the U.S. EPA and are a registered establishment. These systems meet the safety and sterilization performance requirements of the Lighting Inspired UVC Alliance by using third-party testing protocols. Manufacturers must use third-party testing protocols in order to bring products to market and have to retest, retrain, and register their companies annually. Laundry, the dryer wash, and trash collection rooms are disinfected with passive cleaning technologies. Vigorous controlled cleaning is being used in coordination with UVC. The infant facility also boasts a half gallon-a-minute UVC water sterilization system in place.

4. Safety Measures and Precautions for Using Germicidal Light Bulbs and Fluorescent Tubes

Since germicidal light bulbs and fluorescent tubes emit UV radiation, there are potential risks associated with using these lighting technologies that should be taken into consideration. As damaging ultraviolet rays can potentially pose risks to human health and the environment, only qualified technicians should install these devices. By positioning germicidal light bulbs and fluorescent tubes effectively, it is possible to limit and control their damaging effects. In certain operational conditions and installations, the daily allowed time of exposure to uncontrolled UV radiation varies. Certifiable personal protective equipment should be worn by individuals working on the installation, maintenance, and replacement of germicidal light bulbs and fluorescent tubes as needed, particularly if the sources are switched on via programmed control systems or if they are connected to an electric connection device without an on-off switch.

Disinfection and sterilization systems based on the use of germicidal light options could be made safer through safety awareness and proper use. The need to inform the public about UV light safety through education campaigns is outlined. Regulations and standards governing proper use of germicidal light options are mentioned. A balance needs to be struck between extending the efficacy of UV devices and reducing potential threats to human health and the environment. The use of germicidal light is an effective disinfection and sterilization method. Safe use is addressed in this chapter with a specific focus on the usage of direct and indirect germicidal ultraviolet (UV) light sources.