nCoV

Does UV Lamp Really Works to Kill Coronavirus (covid-19)?

nCoV

At the beginning of 2020, a sudden new coronavirus (COVID-19) swept the world at an unprecedented rate. People are rushing to buy masks, disinfection water, alcohol, and of course ultraviolet disinfection lamps.

According to the latest research, 75% alcohol, ether, chloroform, formaldehyde, chlorine-containing disinfectants, peracetic acid and ultraviolet light can inactivate viruses.

Many consumers may feel that the use of ultraviolet germicidal lamps is unnecessary.

In fact, we live in a ubiquitous environment of bacteria:  air,  the corner of the kitchen, toilet, desktop,  mobile phone, even clothes … are viral bacteria that we cannot see with the naked eye.

Kindergarten is a place where children gather. For example, there are many bacteria in the air or on toys. Once a child is sick, parents have to take time off to look after the child and go to the hospital, which requires a lot of energy and money.

Osram (a well-known German lighting company) once did a study. The results of the study showed that the kindergarten that uses ultraviolet sterilization lamps reasonably and standardized, the child attendance rate increased by 1% to 5%.

Visible UV lamp does have an effect on sterilization, so what is the principle?

First, we need to understand several concepts.

uv-spectrum

What is ultraviolet(UV) light

Ultraviolet light is electromagnetic radiation or light between the visible spectrum and X-rays. Ultraviolet light has a wavelength in the range of 10 nm to 400 nm and an energy of 3 eV to 124 eV. It is named for it is closest to the purple portion of visible light. Scientists divided Ultraviolet radiation into three different bands: UVA, UVB and UVC. (types of UV light)

UVA

UVA has the longest wavelength compared to the three bands. Its wavelength range is between 320-400 nm. UVA rays represent up to 95% of UV radiation reaching the Earth’s surface. UVA rays are very powerful, they can also enter some clothes, mist or even glass. Similarly, UVA rays help the skin mature and wrinkle as they penetrate deep into the skin and damage the underlying cells.

UVB

The UVB wavelength is 290-320 nm. The UVB ray intensity varies depending on the season, area and time. They are most prevalent in the northern half global summer months or in the Earth’s orbit closest to the Sun. UVB rays are the main cause of skin whitening and sunburn, and often damage the superficial skin’s surface.

UVC

The wavelength of the UVC rays is 200-290 nm. These rays have the shortest wavelength. They are the most dangerous rays. Nonetheless, when the ozone layer completely absorbs them, these rays did not reach the earth’s surface.

 

How do UV lamps kill coronavirus?

The working principle of ultraviolet sterilization uses UVC ultraviolet rays (mainly 240 nanometers to 280 nanometers) with bactericidal effect to destroy the molecular structure of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) of microbial cells, resulting in growth cells and (or) regeneration Sex cells die to achieve the effect of sterilization.

Do n’t be too tangled about what kind of germs it can kill. Anyway, it can kill most bacterial viruses including this new coronavirus (you do n’t know which bacterial viruses exist in your family) Kill.

How do the UV lamps shine?

All coronaviruses are single-stranded positive-strand RNA viruses. So how do UV lamps emit UVC ultraviolet rays?

There are two main light sources of ultraviolet germicidal lamps – gas discharge light source and solid state light source.

Gas discharge light source

The gas discharge light source is mainly a low-pressure mercury lamp. The luminescence principle is the same as the fluorescent lamp we used before, which excites mercury atoms in the lamp tube. The low-pressure mercury vapor mainly produces 254 nm UVC ultraviolet radiation (radiation efficiency 30% ~ 60%) and 185 nm UVD ultraviolet radiation (radiation efficiency 5% ~ 15% ).

Argon_discharge_tube

However, ultraviolet rays can only propagate in a straight line, and the penetration is weak, so there is a blind spot for disinfection.

Although the 185 nm UVD does not have a strong and effective physical sterilization effect, it can decompose the oxygen in the air to generate ozone. Ozone has a strong oxidizing effect and can reach all corners with the air flow to complete sterilization (biochemical oxidation Sterilization).

However, high ozone concentration is harmful to the human body and can cause chest tightness and dizziness. When you purchase an ozone-type ultraviolet lamp for sterilization, you need to open the window for 30 to 60 minutes to stay.

The advantage of the low-pressure mercury lamp is that the technology is mature and the sterilization efficiency is high, but there is a large amount of mercury pollution (it is best to put it out of reach of children).

Solid-state light source

Solid-state light source refers to UV-LED light source. The radiation efficiency of UV-LED ultraviolet rays is several orders of magnitude lower than that of low-pressure mercury lamps, which can only reach 3% -5%.

The cost of UV-LED light source is also very high. If you want to achieve the same unit radiation dose, its price is much more expensive than low-pressure mercury lamps.

Some companies are already using UV-LEDs in water purifiers, air conditioners, and air purifiers. I believe they will be widely used in the civilian sector as the cost of technology decreases in the future.

Here are a few more common types of UV Sanitizer.

Types of UV Sanitizer

 1. Portable type

This is the first choice for home use, most of them are equipped with timing / remote remote control / infrared sensor function, which is safe and convenient.

Of course, you still need to pay attention to safety protection when using it, and read the instructions carefully.

2. Integrated bracket type​

uv lamp tube

This kind of lamp is often used in spaces such as hospitals / food processing factories / school canteens that have strict requirements on pollution and purification environment. Generally fixed on the wall or hung on the ceiling, ready to use.

You can use it at home, but I do n’t recommend this because it ’s inconvenient. Although the sterilization effect of this lifting is better than the portable mobile type.

3. Wall-mounted

UV-lamp-1

You can see them in factories, restaurants, warehouses, kindergartens and other places. If you buy this at home and can’t hang it on the wall, the effect on the ground is not so good. The appearance is not too beautiful, unless it is consistent with your decoration style.

4. Handheld

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How much power do I need?

If our ordinary consumer families choose UV lamps, they do not need high-standard sterilization requirements.

There is a rough formula for calculating the power of ultraviolet germicidal lamps: 1 cubic meter is equipped with 1.5W ultraviolet lamps.

For example, if your bedroom is 15 square meters and the floor height is 3 meters, then the required UV lamp power is 15 × 3 × 1.5 = 67.5W.

In other words, you need to buy a 60W ultraviolet germicidal lamp.

Ozone or no ozone?

Choose between ozone and no ozone

Again, no matter whether there is ozone or no ozone, UV disinfection lamps are harmful to the eyes and skin and need to be operated safely.

As mentioned above, ozone can be sterilized completely by air flow to some dead corners to eliminate odors. It is generally used in kitchens and toilets.

However, ozone is harmful to humans and corrosive to rubber, iron products, and plastic products.

Therefore, it is best to collect valuables during sterilization. After disinfection, open the room and ventilate for 30 to 60 minutes (if you still smell a pungent smell, continue to ventilate)

Choose whether there is ozone or no ozone, depending on your family needs.

You may ask, can UV lamps kill cockroaches and insects, especially mites?

Sorry, they can’t

How long does it take to kill coronavirus (covid-19)?

The German Center for Disease Control and Prevention’s Virus Prevention and Control Institute’s 2003 research report pointed out that SARS coronavirus can be killed by UVC with an intensity greater than 90 μW / cm² in 60 minutes.

The inactivation time of the SARS virus is only a reference. After all, this new coronavirus is not a SARS coronavirus. It is related but not the same. They are smarter and more tenacious.

The German Center for Disease Control and Prevention’s Virus Prevention and Control Institute’s 2003 research report pointed out that SARS coronavirus can be killed by UVC with an intensity greater than 90 μW / cm² in 60 minutes.

The inactivation time of the SARS virus is only a reference. After all, this new coronavirus is not a SARS coronavirus. It is related but not the same. They are smarter and more tenacious.

I remind my readers here not to try to illuminate the human body with ultraviolet light. The result is definitely not what you want to see.

How to use them safely?

1. Pay attention to the ambient temperature first.
If the temperature is too high or too low, it will affect the ultraviolet radiation intensity and affect the sterilization effect. The ultraviolet radiation intensity is maximum and stable when the room temperature is between 20 and 40 ° C.
Therefore, when the temperature is lower than 20 ℃ or higher than 40 ℃, it is necessary to prolong the ultraviolet irradiation time appropriately.

2. Second, pay attention to the ambient humidity.
When the humidity is between 55% and 60%, ultraviolet rays have the highest rate of killing bacteria. When the humidity exceeds 60%, the penetration of ultraviolet light will decrease, and the sterilization effect will decrease by 20% to 30%.

It is best used when the weather is sunny and the room is dry. Do not sterilize with a UV lamp immediately after mopping the floor with a wet mop or wiping the table.

3. Do not look directly at the luminescent lamp with naked eyes. Do not expose your skin to the ultraviolet light for a long time.

4. During disinfection, close doors and windows, people and pets must leave the disinfection place. Plants and valuable leather goods and other items should also be moved to places that are not exposed to ultraviolet rays or covered with cloth.

5. Buy a UV lamp with smart sensor or remote control function for safety when you have enough budget.

6. Do not switch the UV lamp frequently, otherwise the output power will be reduced after a long time.

7. After using the UV lamp and waiting for the lamp to cool, wipe the lamp with 75% alcohol to remove dust and oil on the surface.

Conclusion

Finally, I suggest that you should not use ultraviolet lamps to sterilize and sterilize at home every day. It is not that hospital wards, food factories and virus research institutes need to maintain a sterile environment as much as possible.

Otherwise, your body’s immune system resistance will decline, especially for children. Many parents think that only by killing all the bacteria will the child be healthy, but it is not.

Certain bacteria can stimulate the child’s immune system to mature. Therefore, moderate use of ultraviolet sterilization lamps, usually alcohol disinfection is good.

 

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