As nations start to ease their restrictions following the heightening impact of the ongoing pandemic, scientific investigations into potential solutions for detecting and disinfecting contaminated public places against the virus are underway. One such method at the center of these studies is Ultraviolet Germicidal Irradiation (UVGI).
Understanding Ultraviolet Light
Ultraviolet light, a type of electromagnetic radiation undetectable to the human eye, possesses shorter wavelengths than visible light. Originating from the sun, UV radiation is divided into three main types based on their distinct wavelengths – UV-A, UV-B, and UV-C rays.
The biological activity and skin penetration ability differ for each type due to wavelength variations. Typically, shorter wavelengths equate to more harmful UV radiation; however, they are less able to infiltrate the skin. UV light has been proven to be detrimental to cells, increasing the risk of cell mutation leading to cancerous growth with extended exposure.
Classifying UV Radiation
UV-C rays have the shortest wavelength and can be extremely hazardous. However, the Earth’s atmosphere completely absorbs these rays, preventing them from reaching the surface. Medium-wavelength UV-B rays are biologically active but only penetrate the superficial layers of the skin. Exposure to these rays can lead to delayed tanning, burning, skin ageing, and, significantly, the development of skin cancer.
Long-wavelength UV-A rays account for approximately 95% of the UV radiation reaching the Earth’s surface, penetrating deep into the skin layers. These rays are responsible for immediate tanning and also contribute to the development of skin cancers.
UVGI and Its Functioning Method
UVGI pioneers a unique approach by replicating UV wavelengths and utilizing its destructive properties to target pathogens. It offers a promising method to disinfect contaminated spaces, air, and water and help prevent the spread of infectious diseases.
The US Centers for Disease Prevention and Control (CDC) revised their guidelines in 2005 to incorporate the use of UVGI for controlling tuberculosis (TB) spread in hospitals. Scientists suggest fixtures containing UVGI lamps should be mounted high, targeting the upper interior surface area and trapping pathogens. Supplementing these spaces with a fan can help draw air upwards, increasing the efficiency of UVGI against pathogens.
Effectiveness and Factors Influencing UVGI
UVGI notably aids in preventing infections that primarily spread through smaller droplets, eschewing direct contact or larger respiratory droplets. Despite its potential, the effectiveness of UVGI hinges on several factors like sensitivity of microorganisms to UVGI, required UVGI dose/intensity to kill pathogens, prevailing humidity and weather conditions, and room’s air circulation.
However, deploying UVGI extensively in public places such as schools, universities, restaurants, and cinemas can prove to be a costly affair for disease prevention.
DRDO’s Latest UV Developments
The Defence Research and Development Organisation (DRDO) has recently developed automated contactless UV-C devices called DRUVS (Defence Research Ultraviolet Sanitiser) and NOTESCLEAN as part of their efforts to combat the virus.
Consideration of Other Measures
Despite the advancements in technology, practical behavioral changes are still championed as effective defense measures against viruses. These practices include maintaining social distancing and wearing masks. Furthermore, some countries are exploring the idea of issuing immunity passports or risk-free certificates based on the notion of natural immunity.
Word of Caution from WHO
Despite these developments, the World Health Organisation (WHO) has issued warnings against using immunity passports due to the lack of proof of immunity from reinfection of Covid-19. Even if immunity exists, its duration remains unknown.
