UV and COVID-19


he coronavirus vaccine gives us much needed hope that the end of this global pandemic is approaching, as many people want to leave their homes, return to work and get life back to normal. Social distancing, masks, sanitization and hand washing have become a part of, what is being termed, “the new normal”. While these measures have helped limit the spread of the virus to a certain extent, not all forms of transmission have been prevented. Particularly indoors and on surfaces have been a point of major concern for health authorities and countries. The scientific community studying the virus suggest that the novel SARS-CoV-2 stays alive in the air for a number of hours and on some surfaces – for days, going to a normal state of life seems to be a far-fetched hope for citizens.[1]

Universities and companies all over the world have been trying to find ways to disinfect surfaces and air to provide a safe environment for all. Ultraviolet light has been known for its disinfection capabilities since the late 1800s. Scientists discovered that shorter wavelengths, now called UV-C, of UV emitted by the sun, could kill bacteria. UV-C is the shortest and most effective form of ultraviolet, also called germicidal UV, which has been studied for its sterilization properties.   Unlike the longer wavelengths of UV from the sun, UV-C rays are mostly filtered out by the ozone layer protecting the earth’s surface. This has enabled the use of this form of light for effective disinfection as the microbes have not had a chance to adapt to them. Hospital and water treatment plans have relied on UV-C to kill mold, viruses and other microorganisms.

Promising research has been conducted into the study of the effectiveness of UV-C Light on SARS-CoV-2. One of the first studies was done by Christiane et al. in December 2020 to prove the use of UV irradiation on the virus. The paper highlighted that the virus is highly susceptible to irradiation with ultraviolet light [1]. The team of researchers isolated the virus from the nasal swab of a patient suffering from COVID-19. UV exposure was conducted with UVC (254nm) and UVA (365nm) sources from Herolab, Germany. They achieved complete inactivation of the SARS-CoV-2 in 9 minutes at a total emitted dose of 1048mJ/cm2 and confirmed that UV-C irradiation is an effective method for inactivation of the virus.

Another study, published in November 2020, by researchers of Tel Aviv University (TAU) provided similar findings. These researchers used UV-LEDs and have concluded the optimal wavelength for killing the coronavirus. They reported that UV-LEDs operating at a peak wavelength of 285 nm was most efficient considering cost and availability.  [2]

“It doesn’t kill the virus — it renders it unable to reproduce,” says Jim Bolton, Environmental engineer, University of Alberta in conversation with Leslie Nemo

As a result of some studies, UV-C light emitting machines are being utilized in empty subway cars, buses and trams for sterilization. The technology has slowly made its way into consumer culture as well in the form of UV-C wands, lamps and devices for homes and office spaces.

UV-C has found its way into multiple applications during the course of the global pandemic. It has been proven for its effectiveness in the removal of bacteria from water and disinfects surfaces. Some new devices have been introduced into the market. LARQ self-cleaning bottle is one of them. Labelled as “the world’s first self-cleaning bottle and purification system”, it uses UV-C LED light to eliminate bio-contaminants from the bottle [5]. Some other products that were introduced during this time are – the LG wireless earbuds [4], SEIT-UV Autonomous disinfection Robot [3] and Perscientx Violet [6]

With UV light making a mark as an efficient way to kill the virus, more and more interest grew in the use of it to disinfect spaces and surfaces. The city of New York tested the use of ultraviolet lamps to kill the virus on buses and subways. [7]

UV technology at a subway maintenance facility in NYC (Source – CBSnews article dated May 20,2020)

There is an increasing focus on the addition of UV technology for air treatment in the transport industry. The Sonoma Marin Area Rail Transit (SMART) installed UV Light sterilization on their trains on a trial run in 2020 and have been using this technology since. [8]

As a result of increased interest and results, many governments across the globe have taken measures to fully understand the use of UV light to provide safety to their citizens. A new initiative announced in Australia, according to SBS News, mentioned that the federal government has announced 10 million USD for clinical trials of some coronavirus-related technologies. [9]

There has been a huge rise in the number of UV devices in the market due to COVID-19. But, here is the bad news- yes, there are some great results that have been seen using a UV light for disinfection, but not all devices in the market do the job. Some manufacturers use words such as “sterilizing”, “disinfecting” and “germicidal” to reference a device’s ability to kill germs but do not mention which germs. UV-C rays are not safe for human exposure. Some of the devices in the market, claiming to be UV-C, emit completely different wavelengths of light. UV-C light is in the range of 100-290nm whereas the devices that are in the market emit light in the range of 400-500nm(giving a purple hue when seen by the user).

UV Wand on Amazon UK

Be aware of such devices and it is highly recommended not to buy them. The international organization for standardization(ISO) has set out documents for safety limits while handling UV-C Devices in ISO 15858:2016. The European Commission has a safety gate alert system that will help to stay away from these dangerous devices. It can be found on . If you type in – UVC in the free text category, a large list of products that have been banned from the market can be seen. The lighting industry association of UK, in September 2020, released an article warning all users about potentially dangerous products and advising not to buy any UV-C products without seeks assurances that they are safe for use.[10]

Bottom Line

The most effective type of UV light to kill the coronavirus is UV-C. It can effectively disinfect surfaces and spaces. Due care must be taken while choosing the device to do the task depending on the target. While it can disinfect and sterilize the region targeted, the user must be at a safe distance and limit exposure to UV irradiation.


  1. Heilingloh, C.S., Aufderhorst, U.W., Schipper, L., Dittmer, U., Witzke, O., Yang, D., Zheng, X.,Sutter, K., Trilling, M., Alt, M., Steinmann, E., Krawczyk, A., 2020. Susceptibility ofSARS-CoV-2 to UV irradiation. Am. J. Infect. Control 48, 1273–1275.
  2. Gerchman, Y., Mamane, H., Friedman, N., Mandelboim, M., 2020. UV-LED disinfection ofcoronavirus: wavelength effect. J. Photochem. Photobiol. B Biol. 212, 112044.


Covid-19: Potential Wastewater Risks


he coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread widely, becoming a global pandemic. COVID-19 symptoms include cough, fever, difficulty breathing, and diarrhoea. Genetic material from SARS-CoV-2 ribonucleic acid (RNA) has been detected in the faeces of both symptomatic and asymptomatic people who have been infected 1.

This pandemic has become one of the most significant international public health challenges of this century; globally, nearly 53 million cases and more than 1.3 million deaths have been counted to date 2. Tools for rapidly identifying, containing, and mitigating the spread of SARS-CoV-2 are crucial for managing community transmission, particularly until a vaccine or effective pharmaceutical intervention is developed and becomes widely available 3.

Considering recent epidemics that have emerged around the world, there has been increasing awareness regarding the risk of exposure to pathogens during wastewater collection and treatment. Emerging pathogens may enter wastewater systems through several pathways, including viral shedding in human waste, animal farming, hospital effluent, or surface water runoff following biological incidents. Sewage and wastewater systems transport water to wastewater treatment plants (WWTPs), and the water is then discharged into the environment. SARS-CoV-2 viral material poses a significant threat to human health, and their transmission in wastewater systems may lead to increased exposure, potentially causing serious health consequences. This virus is primarily transmitted through person-to-person and aerosol/droplet transmission via the respiratory system, with fomite and touch-based contamination comprising a lesser proportion of cases. Potential exposure and transmission through sanitation systems have not been sufficiently studied and require further evaluation 4 5.

Environmental surveillance has commonly been implanted in public health management, and methods such as testing wastewater for evidence of pathogens can indicate the severity and scope of pathogenic spread in communities. In the context of the ongoing COVID-19 pandemic, environmental surveillance methods are being used to evaluate SARS-CoV-2 shed in wastewater via human waste 6. Wastewater monitoring exhibits significant promise as an early detection approach. However, available data indicate that the role of wastewater as a potential source of pathogens and as a risk factor for public health must be further explored 4.

Further, genetic material from SARS-CoV-2 in untreated wastewater and/or sludge has been detected in many regions, such as Milan, Italy; Murcia, Spain; Brisbane, Australia; multiple locations in the Netherlands; New Haven and eastern Massachusetts, United States of America; Paris, France; and existing poliovirus surveillance sites across Pakistan. Researchers in the Netherlands, France, and United States of America have reported a correlation between wastewater SARS-CoV-2 RNA concentrations and COVID-19 clinical case reports; research from the latter two countries further suggests that wastewater virus RNA concentrations can provide a 4- to 7-day advanced indication of incoming COVID-19 confirmed case data 6.

Recently observations of viral material in wastewater have intensified the need for the acquisition of more information on the transmission pathways of SARS-CoV-2 through various environmental exposure pathways, including that of wastewater. Wastewater is known to be a major pathogen transmission pathway, and contaminated water should be treated carefully to reduce the risk of human exposure 7. Moreover, contamination risk is extremely high in densely populated regions with minimally developed sewage and wastewater treatment facilities. This is particularly critical for SARS-CoVs, as they can survive for several days in untreated sewage and longer in colder regions 8.

Conventional sewage treatment methods that include disinfection are expected to effectively eradicate SARS-CoV-2 8. Despite ongoing treatment strategies, recent studies have shown that SARS-CoV-2 RNA has been found in the outlet of WWTPs as well as in water bodies receiving treated wastewater, indicating a serious public health risk via the faecal–oral or faecal–aerosol infection routes 9. Covid-19 transmission through wastewater poses a major concern in areas without adequate sanitation and water treatment facilities, as discharge of wastewater without appropriate treatment would expose the public for infection 7. Globally, approximately 1.8 billion people access faecal-contaminated water sources as drinking water, which significantly increases the risk of COVID-19 transmission by several magnitudes when proper precautions are not taken8. Therefore, the risk of infection through various forms of contact with conventionally treated wastewater cannot be dismissed.

Owing to the lack of clean natural water resources in many countries, treated and untreated wastewater is increasingly used for irrigation. In addition, sludge from treated wastewater has been applied as fertilizer, and it is increasingly used as an agricultural amendment. The viruses contained in this wastewater and sludge are thus deposited on crops and soil where they are likely to survive for a short period. This can facilitate further spread into ground and agricultural water sources, further increasing the risk of exposure. It is therefore important to understand the survivability of and exposure risk to these viruses, specifically on crops and soil. Studies on viral survivability in such conditions can only be conducted with enteric viruses that can multiply in cell cultures. Complex methods are required as the presence of the viral genome alone does not indicate the presence of infectious viral particles 4.

Wastewater Use in Irrigation Higher Than Thought | Fluence

 Although the extent of infectivity associated with SARS-CoV-2 RNA in treated wastewater is not yet clear, the potential risk can be minimized by ensuring complete viral RNA removal in wastewater treatment plants 9. It may be beneficial to add an additional disinfection step, or ‘tertiary treatment’, to further reduce the risk posed by viral pathogens. Disinfection methods for wastewater effluents and water include physical and chemical techniques, such as ultraviolet light and heat treatments as well as chlorine and ozone treatments, respectively. Ozonation and UV irradiation are reported to be more effective than chlorine-induced reactive oxygen species formation; however, the latter induces residual disinfection, which ozonation and irradiation cannot facilitate 10. Moreover, chlorine addition to create a residue after ozonation can be performed to produce water free of toxic residues. Despite existing disinfection techniques, further investigation is required to determine dose and contact time for SARS-CoV-2 inactivation 4 8. In addition to conventional treatment methods, household disinfection techniques such as boiling, nanofiltration, UV irradiation, and bleaching powder addition in appropriate doses are also effective and should be evaluated for regions without safe piped water supplies and centralized water treatment facilities.


1.      Ahmed W, Angel N, Edson J, et al. First confirmed detection of SARS-CoV-2 in untreated wastewater in Australia: A proof of concept for the wastewater surveillance of COVID-19 in the community. Sci Total Environ. 2020. doi:10.1016/j.scitotenv.2020.138764

2.       WHO Coronavirus Disease (COVID-19) Dashboard. Published 2020. Accessed November 14, 2020.

3.      Hassard F, Lundy L, Singer AC, Grimsley J, Cesare M Di. Comment Innovation in wastewater near-source tracking for rapid identification of COVID-19 in schools. The Lancet Microbe. 2020;5247(20):19-20. doi:10.1016/S2666-5247(20)30193-2

4.      Lahrich S, Laghrib F, Farahi A, Bakasse M, Saqrane S, El Mhammedi MA. Review on the contamination of wastewater by COVID-19 virus: Impact and treatment. Sci Total Environ. 2021. doi:10.1016/j.scitotenv.2020.142325

5.      Mohapatra S, Menon NG, Mohapatra G, et al. The novel SARS-CoV-2 pandemic: Possible environmental transmission, detection, persistence and fate during wastewater and water treatment. Sci Total Environ. 2020. doi:10.1016/j.scitotenv.2020.142746

6.      WHO. Status of environmental surveillance for SARS-CoV-2 virus. 2020;(August):1-4.

7.      Kataki S, Chatterjee S, Vairale MG, Sharma S, Dwivedi SK. Concerns and strategies for wastewater treatment during COVID-19 pandemic to stop plausible transmission. Resour Conserv Recycl. 2021. doi:10.1016/j.resconrec.2020.105156

8.      Bhowmick GD, Dhar D, Nath D, et al. Coronavirus disease 2019 (COVID-19) outbreak: some serious consequences with urban and rural water cycle. npj Clean Water. 2020. doi:10.1038/s41545-020-0079-1

9.      Abu Ali H, Yaniv K, Bar-Zeev E, et al. Tracking SARS-CoV-2 RNA through the wastewater treatment process. medRxiv. 2020:2020.10.14.20212837.

10.    Zhang CM, Xu LM, Xu PC, Wang XC. Elimination of viruses from domestic wastewater: requirements and technologies. World J Microbiol Biotechnol. 2016. doi:10.1007/s11274-016-2018-3