Advancing the potential of UV light for the swine industry
By Peiyang Li, Jacek Koziel, Jeffrey Zimmerman, Jianqiang Zhang and William Jenks
Ultraviolet (UV) light is invisible yet ubiquitous in our daily life. UV light has a shorter wavelength than visible light, so it is more energetic and can be used for germicidal purposes. The sun is a natural source of UV light. Artificial UV sources come from different types of UV lamps (e.g., mercury bulbs).
Generally, UV is categorized into four wavelength ranges:
UV-C light, often referred to as the germicidal wavelength, can be absorbed by nucleic acids and proteins to cause damage. It has been found effective for disinfection in various areas, such as drinking water disinfection, air disinfection and medical applications.
The commercially available, inexpensive UV-C mercury lamps have a peak at around 254 nm. In recent years, there have been some developments in costly far-UVC excimer lamps (207 – 222 nm), which are germicidal while at the same time claiming to be harmless to mammalian skin and eyes.
UV-C LED products are also commercially available. They have a much longer lifespan and energy-saving while the cost is much higher than mercury bulbs.
However, UV-C light cannot penetrate through standard glass or non-transparent materials. Its irradiation also reduces significantly as distance from the UV source increases (Figure 1).
Figure 1. UV light irradiance (I) decreases proportionally to the inverse square of the distance (d) between the lamp and the target.
Currently, the UV applications in swine farms are mostly pass-through chambers for the decontamination of items (shipment deliveries, lunch boxes, small tools) that cross the biosecurity line.
There is a potential to expand the UV-C application to air treatment in the future to mitigate airborne transmission of diseases.
Maintaining good, common-sense safety practices is essential while using UV light. That means, avoiding direct exposure of skin and eyes to UV and wearing protective gear such as UV safety goggles, UV face shields and proper clothing under direct irradiation.
The information above is documented in a white paper funded by Swine Health Information Center (SHIC) and was peer-reviewed and published recently.
Past research Porcine reproductive and respiratory syndrome (PRRS) has been one of the most economically impactful diseases for the pork industry. Properly treating the barn inlet air can mitigate the spread of airborne PRRS virus (PRRSV) from one barn to another.
In a recent project funded by the National Pork Board (NPB #18-160, PI: Dr. Koziel) (Paper 1, Paper 2), we tested the effectiveness of UV in inactivating aerosolized PRRSV, specifically with UV-A (365 nm), ‘excimer’ UV-C (222 nm), and conventional germicidal UV-C (254 nm) lamps in a laboratory setup (Figure 2 and 3).
Figure 2. A lab-scale setup of UV treatment on aerosolized PRRSV in fast-moving air. UV doses were estimated to inactivate PRRSV with different types of UV lamps.
The key advancement was the testing of a recently developed excimer UV-C light (222 nm) that is less harmful to people and livestock while germicidal for MSRA and the H1N1 influenza virus.
This research bridged the knowledge gap by comparing UV treatment effectiveness of three wavelengths (222, 254, 365 nm).
We quantified the surviving PRRSV titer after UV irradiation and estimated the UV-C dose to inactivate PRRSV in fast-moving air. We found that UV-C (254 & 222 nm) lamps are very effective at inactivating PRRSV aerosols with short treatment times (<2 s).
Scaling up research on UV-C treatment of aerosolized pathogens is warranted based on its effectiveness and reasonable costs compared to HEPA filtration. Current research The indoor air quality became an important part of mitigating the outbreak of the COVID-19 pandemic.
UV-C can play a significant role in the decontamination and disinfection of air and surfaces in public areas. However, UV agricultural applications are still limited.
We are currently collaborating with Kryton Engineered Metals Inc. (Cedar Falls, Iowa) and CIRAS of ISU on advancing UV treatment for large indoor spaces.
We upgraded an existing air purification scalable prototype, FastAir (~2,200 CFM), with the addition of UV-C light that can treat indoor air and maintain a healthy environment.
The prototype has been tested in animal production facilities, and data such as particulate matter concentration and airborne pathogens are collected.
Current data showed that the prototype could mitigate the airborne particulate matter (PM1, PM2.5, PM4, and PM10) and almost 100% of airborne pathogens between inlet and outlet. Its long-term, continuous effect on indoor air quality is being tested.
We believe that this research will be beneficial to industrial applications (air cleaning on manufacturer floors, etc.) and also to animal production facilities where UV treatment may be useful for mitigating the transmission of airborne pathogens.
Figure 3. The FastAir (Kryton Engineered Metals Inc.) was upgraded with UV light.
Moving forward We established collaboration with a major UV lamp manufacturer to scale up the work of UV-C to application in swine housing.
Li is a graduate research assistant; Koziel is a professor in the Department of Agricultural and Biosystems Engineering department; Zimmerman is a professor and Zhang is an associate professor, both in the College of Veterinary Medicine; and Jenks is a professor in the Department of Chemistry, all at Iowa State University.
