A bacteriologist told whether bactericidal UV lamps are effective on viruses

The UV lamp is often associated with medicine and the inscription “quartzing” on the doors of hospital rooms. But room sterilization is far from the only purpose of this simple but versatile device, which is widely used in a variety of fields.

doctor-bacteriologist, director of microbiological research department of LabQuest laboratory

“I will tell you where the UV lamp is used, on what principle it works, in which cases it is maximally effective and how safe it is for humans.”

What is ultraviolet?

Ultraviolet radiation itself is just one of the spectra of electromagnetic waves invisible to us. The same definition applies to the familiar X-rays. The difference is in the wavelength, which determines its properties.

The main source of ultraviolet radiation is the Sun. In this regard, the question may arise – why do we need artificial sources of UV radiation, if there is a natural? The trick lies in the very wavelength.

The fact is that ultraviolet is divided into three separate spectra: UV-A, UV-B and UV-C. Only UV-A and a small part of UV-B reach the Earth’s surface, while UV-C is almost all absorbed by the atmosphere.

However, the most effective spectrum of radiation for killing bacteria and viruses is about 254 nm, which is exactly in the range of UV-C. Therefore, these waves can only be effectively affected artificially.

The ability to select the desired wavelength, control its properties and screen it from the overall spectrum is what distinguishes UV lamps from natural sources of radiation. This allows the same device to be used for different purposes.

Where is UV light used?

UV radiation is capable of sanitizing surfaces, water and air, so such lamps are used in medical facilities, laboratories and food industry.

The properties of ultraviolet light are appreciated by dermatologists. UV lamp phototherapy is successfully used in the treatment of skin diseases such as psoriasis, vitiligo, eczema, fungus and shingles.

These devices are also used in the beauty industry – with their help they achieve a beautiful uniform tan in tanning beds, hardening of nail polish, whiten teeth and install light fillings.

UV light against bacteria and viruses

The effect of ultraviolet light is based on its ability to change the structure of molecules and cause various photochemical processes. In the case of cells of living organisms, UV radiation causes disturbances in their DNA, which prevents normal reproduction and survival.

Since DNA contains the information to reproduce new cells, any errors in its structure are critical to this process. It’s like a “damaged telephone” – the final recipient may receive a message with a completely different meaning. It is due to this effect that UV radiation has bactericidal properties.

Nevertheless, some bacteria and viruses can show resistance to UV radiation. For example, bacterial spores, mycobacteria, lipid-coated viruses and bacteria in biofilms show low susceptibility to UV light.

Harm of ultraviolet light to humans

UV radiation affects the cells of the human body in the same way as bacteria and viruses, but unlike them, we have a wide arsenal of defenses. These include effective DNA damage repair mechanisms, a thick epidermis and melanocytes, the cells that produce melanin. This natural pigment gives us a tanned look and protects us from UV light by absorbing and dispersing it.

Although the most active part of the UV spectrum is scattered in the atmosphere, the UV-A wavelengths reach us fully. They are less damaging to cells than UV-C, but penetrate deeper into the skin due to their longer wavelength. Premature aging, age spots and wrinkles are all to blame for long-term UVA exposure.

The worst case scenario is skin cancer. It is UV radiation that is the leading cause of its development. You can face life-threatening melanoma and less dangerous types of disease.

In general, the harm from ultraviolet light depends on the intensity and time of exposure. A small 10-minute walk is unlikely to be dangerous even under the blazing sun. However, if you accidentally relax on the beach and fall asleep, then a person is sure to encounter sunburn. And the long-term consequences of regularly ignoring sun protection measures are almost impossible to predict.

It is worth noting that special UV lamps are unsafe for people in all cases of direct exposure to the skin and eyes. The same applies to tanning beds – their harm is scientifically substantiated and proven. For example, in Australia and Brazil their use is legally prohibited. And in a number of European countries it is possible to tan in tanning beds only after the age of 18.

The real effectiveness of UV lamps

The use of UV lamps for disinfection of premises implies a lot of but, especially in the home. Ultraviolet is essentially the same light, only not visible to us. For this reason, it is trapped and scattered by obstacles such as common household dust.

And if it is possible to provide a perfectly clean and even surface in the laboratory, then to carry out daily major cleaning in the apartment can afford not every housewife. In addition, any shaded areas and corners will remain untreated.

It is for this reason UV radiation is never used as the only way to disinfect surfaces – only together with manual treatment with antiseptics.

Don’t forget that UV light is destructive to materials and surfaces such as plastic, paint and wallpaper. And regular use of a germicidal lamp can turn into repair or damage to things you value. Indoor plants can also suffer from high doses of UV radiation.

Most often, devices with UV lamps are used for air disinfection, placing them in hoods and air ducts – so you can provide a point intensive impact without harm to humans. In combination with open lamps, which are switched on when people are not present, this air purification system significantly reduces the risk of airborne pathogen transmission.

The open lamp is not suitable for continuous use in the presence of humans, but can be used for air purification in special UV recirculators. Since the radiation is isolated inside the device, it is absolutely safe for people – you can stay in its presence all the time.

Do not expect it to be effective as a hospital solution – the fans and the power of the lamp are not strong enough to provide a high force of action on pathogens.

Do I need a bactericidal UV lamp?

The bactericidal effect of UV lamps depends on a large number of factors, most of which cannot be taken into account at home. For this reason, the use of UV radiation is better left for medical or professional use, where the design of devices minimizes the potential harm.

For example, manicurists often use ultraviolet dryers for gel-lacquer – when used as intended, such devices in most cases are harmless.

First of all, UV lamps – a tool for a specific task, where the balance between time and intensity of radiation is important. And only a doctor with specialized knowledge and skills, will be able not only to select the optimal ratio of these parameters, but also to correctly determine the area of exposure and understand whether there is a need for UV therapy in a particular case.

For these reasons, buying a UV lamp for home use is at least inexpedient, and at most – dangerous to your health.