Ebola, MERS, SARS and anthrax spores: We have about 60 super-dangerous and highly contagious pathogens. These pathogens cannot be studied in conventional biological laboratories.
For them, scientists will need a lab that has the highest level of safety: the Biosafety Level 4 Laboratory (also called Biosafety Level 4).
Currently, there are only more than 50 laboratories of this type in the world, of which the largest is the United States with about 15 BSL-4 laboratories. Next is the UK with about 10 rooms. China has two Level 4 Biosafety laboratories located in Harbin and Wuhan, along with a BSL-4 room planned to be built in Beijing.
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Inside BSL-4 Labs: Where viruses can’t get out
At first glance, these laboratories look nothing special. Like any other biological laboratory, it has freezers with freezer, centrifuge and fume hood.
Laboratory kits are also completely normal, test tubes, pipettes, agar plates … What you can find in a high school biology lab in this room will be available.
The difference is that the room is completely closed. Since it was built, it has no windows. All light is artificial.
To enter a BSL-4 laboratory, you will have to go through a door like a submarine’s door. It was the only way out, and it was also the shield that blocked the dangerous pathogens inside it.
Biosafety Laboratory Level 4 (BSL-4)
A day at the BSL-4 laboratory begins with Diane Negley – a microbiologist at the US Army’s Institute of Infectious Diseases Research – from the dressing room. Every employee entering here must change into the clothes they are wearing. Negley would then put on a Scrubs-like outfit of a surgeon, then wear it with a full-body type A protective suit.
A Level 3 Biosafety Laboratory (BLS-3) only requires scientists to wear boots, surgical gowns, goggles, gloves and an N95 respirator. But in BSL-4, wearing full body protection is a completely different experience.
Class A body protective clothing is a mandatory condition for entry into a BSL-4 room.
“It is extremely bulky“The clothes that weigh about four and a half pounds will inflate like a Michelin tire when the positive pressure air duct is attached and turned on. You will have to control a new body 15 cm taller,” Negley said.
It will take up more space, causing you to bump into everything until you get used to it, Negley said.
And the collision itself is a problem. All surfaces and objects in the BSL-4 room are designed to no longer have any sharp edges, in case a scientist accidentally bumped or fell into it causing the protective suit to tear and exposed under deadly pathogens.
That is also why it needs a gas pump to create constant positive pressure. On the one hand, airflow will prevent pathogens from spreading inside if the garment is accidentally broken or punctured. On the other hand, it will provide clean air from outside the room and oxygen to the working scientist.
Even so, the experience of wearing a full-body type A bioprotector is not something pleasant. “Your movements will be limited, because you are grasping and dropping everything through an air layer“, Negley said.
Continuous air flow also makes you quickly lose water and feel thirsty. It is not a good choice to drink plenty of water before entering the room, because no one will want to undress, go to the bathroom and then return to the process of wearing it again.
Scientists work inside the BSL-4 room in Wuhan, China.
Negley says a researcher needs to plan very carefully and meticulously before entering a BSL-4 room. She needed to list down all the specimens, laboratory tools and things she needed to do so that she only had to go through the door once.
Medical condition is also an important thing for scientists who want to enter BSL-4 room. No one will want to go there on a flu day, because running your nose while wearing clothes is an experience that couldn’t be worse. You will not be able to wipe it. And a sneeze will cause the glass to splash with water droplets that cannot be cleaned from the inside.
All scientists who want to work in the BSL-4 laboratory must undergo a rigorous training process. “The first few times they walked in, everyone felt scared and they breathed heavily“, Says Daryl Dick, a senior technician at the Canadian National Microbiology Laboratory.
Some people will never dare to enter the BSL-4 room, because the feeling of being confined in a suit and the dangers in it scares them. Scientists can’t talk easily, because the blowing air will overwhelm every sound they make.
Scientists can’t talk easily, because the blowing air will overwhelm every sound they make.
In a closed room with only white fluorescent lights, facing inanimate fume hoods, air currents whirled in the ears and controlled a bulky outfit, clinging to two plastic shoe soles of It’s on the concrete floor enough to make you feel tired.
Negley says the intensity of the work, physical exertion and isolation make the BSL-4 lab far more exhausting than the standard outside laboratory, with harmless microorganisms.
For his part, Dick believes that once he is used to and can tolerate that, a scientist can put his or her full trust in the safety of a BSL-4 room and handle experiments. expertly.
Where germs can’t get out
Biosafety laboratories are currently classified into four levels BSL-1, BSL-2, BSL-3 and BSL-4.
BSL-1 is commonly used to teach or study non-pathogenic biological agents in healthy adults. BSL-2 can be used to study pathogens of moderate risk, with medication and often not through respiratory pathogens.
The Level 3 Biosafety Laboratory (BSL-3) is built in clinical or research facilities to deal with agents that could cause serious illness or death, with may be spread by inhalation.
Images of the SARS-CoV-2 virus are causing the Covid-19 epidemic – a pathogen that requires BSL-3 and BSL-4.
Pathogens studied in BSL-3 can also be studied in BSL-4. But in addition, Level 4 Biosafety Laboratory is dedicated to extremely dangerous bacteria, viruses and chemicals, has no treatment and can even be deadly right after infection.
A top safety rule is that BSL-4 laboratories must be built in areas separate from residential areas and with extremely limited traffic. It is built with at least two layers of protection. Dick called each BSL-4 room “one box completely enclosed inside another. “
Typically BSL-4 will be housed in a separate building, which can share common space with nearby BSL-3 laboratories. But it has to be completely separate from those common spaces.
Each BSL-4 room is “a completely enclosed box inside another box”.
The BSL-4 has its own supply of air and water, a backup generator to keep it safe even during a power outage.
Contrary to what many people think when looking at it, protective clothing is not the most effective tool to ensure the safety of scientists inside BSL-4, but rather fume hoods and High-efficiency particulate air HEPA (High efficiency filter system).
Fume hoods are cabinets with negative pressure. That is, it has a top-of-the-range air extractor that creates a constant stream of air coming in from its door – where scientists work and manipulate – and exit from the vent to the HEPA air purifier. .
All experiments with pathogens in the BSL-4 room must be done inside this cabinet. As a result, germs will never be able to swim upstream from the closet to the outside to spread the infection. “We are trained to the point where we can work in a fume hood without wearing protective gear“, Dick said to emphasize its role.
Scientists work with fume hoods, a key factor in their safety in BSL-4.
Negative pressure is also essential for the entire BSL-4 room. The suction machines always make the air can only enter the room but can not leave. Therefore, even if the door of BSL-4 room is open, the air (if containing pathogens) in it will not be able to go out, which will be sucked up to a HEPA filter waiting.
HEPA filtration systems are designed with a filter made of fiberglass with gaps only 0.3 micrometres apart. But the special feature of HEPA compared to other filtration systems is that it is able to capture particles smaller than the gap size by taking advantage of diffusion and electrostatic suction mechanisms.
Thanks to this mechanism, BSL-4 can guarantee almost absolute cleanliness (> 99.9999%). The power of HEPA is equipped to allow it only takes 3 minutes to filter and replace all the air in a BSL-4 room.
“Once something goes wrong, [mà hệ thống HEPA vẫn còn đang hoạt động], we know that within 3 minutes, the room will be cleaned without any infectious agents remaining“, Dick said.
HEPA air filtration system of BSL-4 Laboratory.
Meanwhile, all exhaust air outlet from BSL-4 is also blocked by HEPA filter. Ordinary microorganisms cannot survive long outside the human body, they simply die on the filter when trying to raid out.
If they have not died, the filters will also be disinfected and changed regularly to ensure HEPA filtration efficiency.
For wastewater, BSL-4 has a separate chemical treatment system, which ensures decontamination and kills all the pathogens in it. The control of objects and equipment brought in and brought into the laboratory is extremely strict.
All test tubes, test equipment or any items before leaving BSL-4 must be decontaminated using an autoclave. Even right after being removed from the fume hood, they had to be autoclaved.
When large equipment inside BSL-4 such as refrigerators or centrifuges is broken down or needs replacing, the laboratory will perform a full decontamination procedure before allowing a technician to handle them. .
To be safe, this process is done very carefully and can last from several days to several weeks. No pathogen can take advantage of that opening to escape, thanks to attachment to broken surfaces when they are removed.
Of course, during the repair process, samples of dangerous viruses and bacteria were moved to another safe storage.
BSL-4 laboratory wastewater treatment system.
All of the combined measures have ensured that a Level 4 Biosafety Laboratory cannot spread pathogens to the environment on their own. The only pathway that pathogens can take advantage of is the scientists working inside it.
But the rules that apply to scientific staff continue to make that impossible. One is that the pathogen can never penetrate inside positive pressure protective suits. Secondly, the pathogens on which will be completely eliminated in 5 minutes with a chemical bath of decontamination with a capacity of up to 200 liters of discharge each time.
Dressing procedure in BSL-4 laboratory
The scientists were then asked to shower again, to wash away any fragments of the virus that clung to during protective clothing, before putting on their clothes and returning to the outside world.
Very strict security procedures are also applied in work processes and around the building. For example, every scientist who comes to the BSL-4 laboratory must be licensed and wear a badge, must have a identity check, including iris scanning. They have to record everything they do in a diary and have surveillance cameras to collate.
Security personnel are heavily concentrated around BSL-4 to all the roads, alleys coming in and out of there, to make sure no one overcomes the safety measures, security.
Monitoring center at China National Biosafety Laboratory.
After all, Level 4 Biosafety laboratories are built to study the world’s most dangerous pathogens, to find ways to treat them, prevent them and predict possible diseases. out in the future.
Therefore, the safety measures of BSL-4 have been designed to prevent it from becoming a source of pathogens. By simply obeying those rules, the scientists working in BSL-4 will be safe, and so will the outside world.
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