Why you don't need a UV sterilizer for keys, smartphones and other little things

If you want to be sure to get rid of bacteria and viruses, it is better to disinfect the surface with a solution of alcohol.

Portable UV sterilizers have different names. For example, UV boxes or disinfectant boxes. They can vary in appearance and even include wireless smartphone chargers. But the principle of operation of all such devices is the same: small objects are placed inside the box, and ultraviolet light kills bacteria, fungi and viruses living on their surfaces.

In theory. In practice, the effectiveness of portable UV sterilizers (whatever they are called) is a big question.

What's wrong with UV sterilizers

There are at least a few points that call into question the rationale for buying these devices.

Ultraviolet light does not get rid of all viruses and germs

Short wavelength 100-280 nanometers, UVC (UVC) does indeed destroy the DNA and RNA of living organisms, including bacteria, fungi and viruses. And best of all - at a wavelength of about 250 nm. That is why it is called bactericidal

Firstly, shortwave ultraviolet light is not a panacea. Quartzization (as the process of UV radiation is called) does not guarantee that absolutely all pathogens will be destroyed. It only reduces their concentration in the air and on surfaces.

Secondly, the efficiency of quartzing dependsUsing Ultraviolet Germicidal Lights for Air Cleaning from many factors, including:

• UV power.
• Exposure time.
• The distance from which processing is carried out.
• Humidity of the ambient air. The higher it is, the lowerAerosol Susceptibility of Influenza Virus to UV-C Light bactericidal and antiviral effect of ultraviolet radiation.
• Specific microorganism. Some bacteria or viruses are more sensitive to UV, others less. And about some in general, little is known. For example, SARS ‑ CoV ‑ 2, like other coronaviruses, is assumed to react2020 COVID ‑ 19 Coronavirus Ultraviolet Susceptibility at UVC. But there is no research to support this. Moreover, there is no data on what radiation power and at what humidity air must be used to destroy SARS ‑ CoV ‑ 2 on objects completely, and not partially.

That is why doctors, even in ideal conditions, considerApplications of Ultraviolet Germicidal Irradiation Disinfection in Health Care Facilities: Effective Adjunct, but Not Stand-Alone Technology quartzing is an effective additional, but not an independent method of disinfection.

Portable UV sterilizers are poorly understood

Everything that we wrote above related to quartzization, which is performed in hospitals or public places using special devices - industrial ultraviolet bactericidal irradiators. The effect of such devices has been studied best of all, but there are also questions about it.

Portable UV sterilizers are even less clear. They have been studied very little.

For example, in thisDisinfectant Activity of A Portable Ultraviolet C Equipment work scientists have placed in an ultraviolet box (issued by a verified medical manufacturer, this is important!) six common hospital bacteria and found that after treatment with short-wave UV radiation for 2 minutes, their concentration decreased by 99.9% and even more.

Everything is good, but the results of the study have not been double-checked against other microbes and viruses. Therefore, how does the same UV sterilizer affect, for example, a virus flu, pneumococcus or, say, coronavirus, is unknown.

In general, science has doubts about such disinfectants.Portable Ultraviolet Light Surface ‑ Disinfecting Devices for Prevention of Hospital ‑ Acquired Infections: A Health Technology Assessment and considers the evidence for their effectiveness inconclusive.

This is why neither WHO nor the US Centers for Research and Disease Control (CDC) recommends the use of portable UV sterilizers at home.

The effectiveness of UV sterilizers depends on the manufacturer

The manufacturer must take into account all the factors that affect the ability of ultraviolet radiation to destroy viruses and bacteria, and add answers to the following questions on the packaging and in the instructions for the device.

• What kind of radiation is used in the UV sterilizer: really short-wave ultraviolet (UVC) or medium-wave (UVB) and long-wave (UVA), which are less dangerous for viruses and bacteria?
• What is the power of the device?
• What is the bactericidal effect, that is, what percentage of bacteria and viruses can the device destroy?
• After how many minutes of work is this effect achieved?
• What should be the humidity and what to do if it is higher or lower?

If there is no information about this, it is not at all a fact that the UV-box can disinfect something.

But even if a detailed instruction is attached to the device, this is not a guarantee that the device really works with the exact accuracy and efficiency indicated on the box. Especially if its manufacturer is a small noname ‑ factory from China.

More or less you can only trust devices from well-known companies that specialize in the creation of medical equipment and have already proven themselves well on the market.

There are simpler and safer disinfection methods recommended by WHO and CDC

Scientists have comparedDisinfectant Activity of A Portable Ultraviolet C Equipment the effectiveness of UV sterilizers and classic disinfectants. And it turned out that, for example, alcohol (with a concentration of at least 70%) copes with bacteria, fungi and viruses at least as well as the highest quality professional UV sterilizers.

At the same time, the effectiveness of alcohol has been scientifically confirmed, and WHOFrequently asked questions about infection control measures to protect the health of healthcare workers, caring for patients with suspected 2019 ‑ nCoV infection or with confirmed infection 2019 ‑ nCoV and CDCCleaning And Disinfecting Your Home recommend using it even to combat SARS ‑ CoV ‑ 2.