HVAC UV LIGHTS FOR AC SYSTEMS - DO THEY WORK?

Scientists measure light energy on a scale called the electromagnetic spectrum. This energy includes many things you have likely already heard of like infrared light, radio waves, gamma rays, X-rays, and visible light.

Ultraviolet radiation is the part of the electromagnetic spectrum in between visible light and x-rays. It gets its name because it has slightly shorter wavelengths than violet, the shortest wavelength of visible light. This is also where the name infrared comes from – it has slightly longer wavelengths than red light.

Not all ultraviolet radiation is created equal. There are three different types that are classified according to wavelength. The three main types of UV are UVA (315 nm – 400 nm), UVB (280 nm – 315 nm), and UVC (100 nm – 280 nm). All three types are found in sunlight, but only UVC is used to disinfect surfaces and objects.

• UVC produced by the sun doesn’t cause us any damage because the atmosphere absorbs the radiation before it can come to Earth. UVA and UVB can cause sunburns and skin cancer, but UVC causes the most damage to living tissues because of its short wavelength and high energy, so it’s lucky we are not regularly exposed to it.

  
  

  UVC does not just damage human skin – it’s also extremely dangerous for bacteria and other microbes. This is why only UVC can be used for disinfecting. The high-energy waves of UVC interfere with the genetic material of microorganisms, stopping the cell from replicating this material. This halts reproduction, so the germs die out, leaving a sterile surface.

  
  

  UVC is one of the best ways to kill microorganisms, but it does have its drawbacks. It relies on surfaces and objects being in the path of the light, so systems have to be set up so all target surfaces have a strong source of light. It also can cause a lot of damage to human skin. Lastly, it’s too powerful to be used on any product that includes microorganisms like vaccines.

  
  

  UVC radiation is extremely effective when used correctly. However, it does have a few limitations. First, it can only disinfect objects in the path of the light, so sometimes multiple bulbs are required. Second, UVC is harmful for humans as well, so systems need to be designed in a way to minimize human exposure. Finally, UVC is so good at killing microorganisms that it cannot be used on biomedical products like vaccines, though it can be used on medical equipment that does not contain any organic material.

  
  
  
  

• UVC can be used in many places for disinfection. One way you may have seen it already is in a laboratory class in high school or college. Those cabinets on the wall that you put your goggles in are called biosafety cabinets, and they use UVC to disinfect goggles and other safety equipment. Hospitals have these systems as well for their supplies.

  
  

  Here are some of the major ways that UVC disinfection systems work:

  
  

  * Surface systems: This is the most common type, and it works by shining UVC light directly onto a surface or object. These work well for smooth surfaces, but may not be completely effective for coarse or dense surfaces like rugs. Textured surfaces can introduce hiding places for microorganisms, as well as microscopic shadows on surfaces. Only microbes exposed to the light will die.

  
  

  * Air systems: These systems rely on the natural circulation of air in a room to bring bacteria close to a lamp shining in the air. The system can also have built-in air circulation to improve its effectiveness.

  
  

  * Water systems: Spas and swimming pools use UVC light to disinfect the water without chemicals. UVC light is shone directly into the water, killing bacteria. These systems are usually just part of a broader cleaning strategy that includes filters and possibly chemicals like chlorine.

  
  

  The best thing about using UVC for disinfecting is that it can be used anywhere that light can sine through, and it doesn’t leave any chemical residues. There are many companies out there, including FREE COOL, that produce lamps for use in commercial and residential buildings, schools, hospitals, gyms, public spaces, warehouses, and of course, hospitals.

  
  

  People rely on disinfecting strategies to keep themselves safe and healthy, especially during the current COVID-19 pandemic. Research has indicated that UVC disinfection can help protect surfaces from COVID-19, and can help prevent its spread along with other methods like contact tracing and social distancing. UVC disinfection was already very commonplace before COVID-19, but now it may prove even more important for protecting ourselves and our families.

  

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  According to the CDC, there are currently over 2.6 million cases of coronavirus (COVID-19) in the United States, resulting in over 128,000 deaths. This pandemic is affecting the lives of people all over the world, and everybody is looking for ways to contain and fight the virus.

  
  

  Sales of ultraviolet (UV) sterilization equipment are skyrocketing. After all – if UV technology is good enough for hospitals and laboratories, certainly it must help in the fight against this pandemic virus.

  
  

  The good news is that UV, particularly UVC absolutely can help fight COVID-19. But there are some misconceptions circulating about the role UV plays in managing the virus. This article is here to make some clarifications about how UV can be used to kill COVID-19.

  
  

• Not all UV radiation is identical. UV is classified according to its wavelength and energy. The three main types of UV are UVA (315 nm – 400 nm), UVB (280 nm – 315 nm), and UVC (100 nm – 280 nm).

  
  

  UVC is the most energetic of these three types, and it is the type used in UV disinfection. In nature, almost all UVC is blocked out by the atmosphere, so we are never exposed to it when we go outside. It’s UVA and UVB that give us sunburn.

  
  

  But that doesn’t mean UVC can’t harm us when we are exposed to it. Because UVC is so high-energy, it is highly destructive to living tissues. The same sunburn that would take a few hours of sun exposure can occur in minutes from UVC. This also makes it great at killing bacteria and viruses.

  
  

  When bacteria and viruses are exposed to UVC, their genetic material becomes mutated and they can’t reproduce. Because viruses are not true cells – just protein-covered pockets of genetic material – UVC can destroy or deactivate viruses.

  
  

• Coronaviruses are actually nothing new. While COVID-19 is a new strain that’s causing a lot of problems, coronaviruses are actually a family of viruses. There was a fairly serious outbreak of a coronavirus called SARS-CoV in 2003, and researchers did some studies at that time about whether UVC could be used to deactivate it.

  
  

  The results – it can. This is promising news for COVID-19, which is actually just a mutant of the virus from 2003. UVC can kill the COVID-19 viruses on surfaces, and researchers are even working on establishing minimum doses of UVC for sterilizing used N-95 respirators. Given the pressing need for protective equipment in hospitals across the world, this could be an important development.

  
  

• Though UVC has the potential to kill COVID-19, it’s not as simple as shining a bright UVC lamp on every person entering a supermarket, which, believe it or not, somebody did recently suggest to a UV tech company.

  
  

  It all goes back to how dangerous UVC is. UVC is a great disinfecting tool for surfaces and equipment, but it is not safe for use on or around skin. The WHO specifically recommends against exposing skin to UVC light.

  
  

  There are a number of safety considerations that companies need to consider before using UVC technology. These include providing adequate protective equipment, extensive training on how to operate the equipment, and minimizing exposure time for all employees.

  
  

  As far as UVA and UVB, there is not a lot of evidence they can do much against COVID-19. While sunlight, which is full of UVA and UVB, is a common water sterilization technique in developing nations, it takes hours for it to work. Meanwhile, the same study that showed that UVC can deactivate SARS-CoV showed that UVA is pretty much useless at deactivating the virus.

  
  

  UVB could prove more promising, but the research just isn’t there yet to support it. Bad news for anybody hoping the virus would fry in the sun this summer.

  
  

• UVC in general has some limitations as far as its ability to kill everything on a surface or piece of equipment. It only works if light hits the pathogen, so textured surfaces often create microscopic shadows that viruses can hide in. There’s also the logistical problem of making sure the light hits all the surfaces of the room. So while UVC is a great, clean method of sterilization that involves no harsh chemicals, it is far from perfect. That's why is important to identify the optimal UVC solution in terms of power and light positioning abilities to reach surfaces beyond shadows.
  

  Instead of relying on UV sterilization entirely, it’s important to use it in the context of a larger sanitation strategy. UVC is a great complement to surface cleaning killing any viruses left behind afterwards.

  
  

  Like any strategy for fighting this deadly virus, UVC is one tile in a mosaic of tools. Our best bet against COVID-19 is to use UVC safely along with other sterilization methods, social distancing, and contact tracing.

  
  

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  UV (ultraviolet) light is invisible light energy just outside of the range of visible light that travels in waves. UV is all around us because it is made by the sun. But it is also used in many industrial applications like germicidal lamps for disinfecting surfaces, air, and even water, blacklight inspection for quality control and law enforcement, and even curing certain industrial materials.

  
  

  UV light is classified into different categories based on its wavelength. There are three main types of UV:

  
  

  * UVA (315 nm – 400 nm)

  
  

  * UVB (280 nm – 315 nm)

  
  

  * UVC (100 nm – 280 nm)

  
  

  UVC is the highest-energy form of UV radiation and is the type used for disinfection. A wavelength of 253.7nm is most often emitted by low-pressure germicidal lamps. This article discusses some of the safety concerns of UVC radiation and ways that employers and individuals can mitigate these concerns through both engineering controls (about the system as a whole) and administrative controls (providing guidance and equipment to individuals using the system).

  
  

• UVC light from the sun is absorbed by the atmosphere, so the risk of UVC exposure from going outside is minimal. Most UVC exposure occurs from germicidal UVC disinfection systems. Of the three types of UV light, UVC is the most damaging to living tissues because it has the highest energy. However, it also does not easily penetrate the skin, so most damage from UVC radiation occurs on the surface of the skin or in the eyes, which are much more sensitive than the rest of the skin. The health effects from UVC can be either acute (short-term) or chronic (long-term). Acute effects of UVC exposure include:

  
  

  * Redness or irritation of the skin

  
  

  * Erythema (sunburn)

  
  

  * Eye injuries or irritation

  
  

  Chronic effects of cumulative UVC exposure include:

  
  

  * Premature aging of the skin

  
  

  * Skin cancer

  
  

  Because UVC has the most potential for acute health effects of the three forms of UV light, it’s important that employers and individuals are aware of these risks and take adequate steps to ensure safety. UVC safety is a multifaceted strategy and involves both preventing exposure through engineering controls and through administrative controls.

  
  

• Engineering control measures for UVC safety are designed to minimize the general exposure to UVC radiation by optimizing UVC systems for the space they are in and the purpose they serve. Here are some of the engineering controls to consider for UVC safety.

  
  

  Location

  
  

  When possible (for example, for biosafety cabinets), UVC systems should be kept in a separate space from where people work. When this is not possible (like in a system designed to disinfect the air in a working laboratory), the switches should be wired in series or placed in a separate room only accessible to authorized individuals. This can ensure that the system is only running when employees are safe from exposure.

  
  

  Interlocks

  
  

  Systems for sanitizing equipment like biosafety cabinets should have some sort of interlock system to stop them from emitting UVC when open. This is sometimes built into a system, but some manufacturers also produce retrofit kits to add an interlock system to a biosafety cabinet.

  
  

  Viewports

  
  

  A viewport allows a worker to see the UVC lamp without exposing themselves to UVC light. This is important for general protection and awareness in the workplace as well as for maintenance and repairs to the system.

  
  

  UV Filters

  
  

  UV filters should be considered when deciding on the layout of a workplace using a UVC system. Well-positioned filters can provide an extra layer of protection when preventing exposure entirely is not possible.

  
  

  Emergency Stops

  
  

  All UVC systems should be equipped with an emergency stop to prevent excess exposure in the case of an accident or catastrophic failure.

  
  

  Managing Reflected Light

  
  

  UVC systems are often installed in places with other equipment around, which are often made of reflective metal or other materials. Reflected UVC light is also hazardous, so these reflective surfaces should be painted with a non-UVC-reflective paint. This is generally not a specialized product – most common paints absorb UVC light, especially darker colors.

  
  

  Exposure Limit Values

  
  

  The International Commission on Non-Ionising Radiation Protection (ICNIRP) have established safe limits for UVC exposure (exposure limit values). These values are based on the level of UV light exposure below which individuals can be repeatedly exposed without adverse health effects. These limits should be accounted for in manufacturer’s guidelines for using UVC systems and be indicated in the instructions, including a maximum exposure time per eight-hour workday.

  
  

  If this data is not available, measurements and assessment will have to be made to establish these values for a given system. This will require the assistance of a specialist with the appropriate tools and knowledge.

  
  

• Administrative controls for UVC safety ensure that employees are protected on an individual level and aware of their role in ensuring safety. Here are some of the factors that should be considered.

  
  

  Optimizing Workflow to Minimize Exposure to UVC

  
  

  Access to the UVC system should be limited to those personally involved in its use. Additionally, UVC use should be scheduled in such a way as to minimize the number of people in the area when the system is active.

  
  

  Personal Protective Equipment (PPE)

  
  

  Employees need to be provided with and trained in the use of personal protective equipment (PPE) for UVC exposure. Because so many materials absorb UVC, most uses (except for face and eye coverings) do not require specialized PPE, but this PPE needs to be worn whenever there is a risk of UVC exposure (even if the task at hand might not otherwise warrant so many layers of protection). Some of the forms of PPE for UVC exposure include:

  
  

  * Goggles: Ensure that the model of goggles worn are approved for protection from UVC and also provide wraparound protection.

  
  

  * Face shields: Face shields provide better protection than goggles alone, which may protect the eyes but not the skin on the rest of the face. When possible, wear a face shield in conjunction with goggles.

  
  

  * Gloves: Nitrile gloves protect well against UVC, especially when thick gloves are used, or thin gloves are used in a double layer.

  
  

  * Lab coats: Most clothing in general absorbs UVC light, but employees should wear lab coats as an additional layer of protection, as well as for general protection against other hazards involved in the task at hand.

  
  

  Training

  
  

  Anybody operating or working near the system needs to be aware of its operation and the individual rules and regulations in place for that system. This should include points such as:

  
  

  * A list of individuals who are authorized to use the system

  
  

  * What times the system is activated

  
  

  * Proper use of personal protective equipment

  
  

  * Acute and chronic symptoms of UVC exposure

  
  

  * Understanding of all warning signs and labels on the UVC system

  
  

  * Understanding all procedures in place for using the UVC system, including what happens in the event of a malfunction. Training should be renewed at regular intervals depending on need and staffing.

  
  

• UVC is one of the most effective ways of disinfecting surfaces and equipment. It uses no harsh chemicals, leaves no residue, and it is extremely effective when used correctly. However, the significant health risks of UVC mean that this technology must be used wisely and safely.

  
  

  This article provides some of the guidelines that employers, employees, and individuals can follow to protect themselves and their workplace against overexposure to UVC. But the most important step is to remain aware of where UVC exposure occurs in the workplace, as well as the manufacturer’s guidelines for using UVC systems. With the proper training and equipment, UVC disinfection systems can provide a comprehensive way to kill harmful pathogens in any workplace that requires it.