Can UV Germicidal Lamps Really Kill Bacteria?

Recently, due to the impact of new coronary pneumonia, "disinfection" has become a high-frequency vocabulary in life. The "New Coronavirus Infection Pneumonia Diagnosis and Treatment Plan (Trial Version 6)" states that "viruses are sensitive to ultraviolet rays and heat."

As a result, many people have turned their attention to ultraviolet germicidal lamps.

How does ultraviolet light kill bacteria?

Ultraviolet is a kind of light with a wavelength range of 200nm-400nm. According to the wavelength, it is divided into long-wave ultraviolet (UVA), medium-wave ultraviolet (UVB), and short-wave ultraviolet (UVC). The wavelengths are:

UVA: 315nm~400nm;

UVB: 280nm~315nm;

UVC: 200nm~280nm.

UVC can destroy the structure of microbial DNA and RNA, making them lose their reproductive function. The ultraviolet light generated by the ultraviolet disinfection lamp belongs to UVC, so it is widely used in the disinfection of air and surface of objects.

What is the effect of UV sterilization? 

Many UV germicidal lamp products claim that the sterilization rate is 99% or even 99.9%. Can such a high sterilization rate be achieved? We commissioned (Guangdong Province Microbiological Analysis and Testing Center) to select three common microorganisms in life, Staphylococcus aureus, Escherichia coli, and Candida albicans, to conduct microbial killing effect experiments, and the following test results were obtained.

According to the test sheet, it can be seen that the sterilization rate of ultraviolet germicidal lamps is as high as 99.9% 

 However, the ultraviolet disinfection lamp is a "cutting edge", which has advantages and disadvantages. It has the advantages of high sterilization efficiency, but it is easy to cause harm to the human body when used improperly. 

 How to choose the UV lamp? Is the greater the power the better?

Then there are ozone and ozone-free products on the market, should we choose? Let's first understand the difference between ozone-free and ozone-containing UV germicidal lamps.

The ozone-free ultraviolet germicidal lamp mainly relies on UVC ultraviolet rays with a shorter wavelength to achieve sterilization, while the ozone-type ultraviolet germicidal lamp mainly relies on the ozone generated by the ionization of oxygen molecules in the air by the shorter wavelength UVC ultraviolet rays to achieve sterilization. The purpose of killing microorganisms.

Ozone type: 

 Advantages: Ozone has a strong oxidizing effect, which can effectively kill bacteria. The dispersibility of ozone can just make up for the shortcomings of ultraviolet rays that only travel in a straight line and disinfection.

Disadvantages: However, if the ozone exceeds the standard, it will strongly stimulate the human respiratory tract, causing sore throat, chest tightness and coughing, causing bronchitis and emphysema, so it is necessary to open the window for ventilation.

Ozone-free type: 

 Advantages: no ozone, people can enter the room immediately after sterilization. 

 Disadvantages: It spreads only in a straight line, and there are dead ends in disinfection.

Wake up to everyone, if you buy a UV germicidal lamp with ozone, you must ventilate for more than half an hour after use before entering the room. If you can smell "sunlight" or "rust" after ventilation, it is recommended to extend the ventilation time. !

Tips: 

 When the ultraviolet light is turned on, people, animals and plants must leave the scene and avoid looking directly at the ultraviolet light source. It is recommended that the sterilization time be more than 30 minutes, and the site should be ventilated after sterilization to dispel the residual odor after the death of bacteria and viruses.