Starting work in a new lab is exciting. You’re ready to begin doing awesome science and making new discoveries. However, safety comes first. You need to protect yourself, your colleagues, and your environment from the biological organisms and agents that you work with in the lab. Biosafety levels are a way of classifying the precautions you must take (based on the agents that you work with) to practice safe science.

There are four different levels of biosafety as defined by the Centers for Disease Control and Prevention. The first level starts out with minimal precautions because of the minimal risk to biosafety. Safety measures increase over the next three levels in proportion to the risk presented by the organisms and agents to you and your environment.

Here, I give you short introduction into the four biosafety levels.

Biosafety Level 1

We have all been to Biosafety Level 1 (BSL-1) laboratories. Be it the everyday struggle to clone your favorite gene into E.coli or isolating plasmids, our BSL-1 laboratories have witnessed it all. In BSL-1 labs, you work with well-characterized agents that do not cause any disease or harm in adults with healthy immune systems (immunocompetent).

BSL-1 labs have individual doors and at least one sink for hand washing, but the labs don’t need to be isolated within a building. You also do not need any special containment equipment or facility design in BSL-1 labs.

In BSL-1 labs, you can work out in the open on your bench using standard microbiological practices. But you still should know the potential risks of the agents you are working with. Make sure that you receive specific training in the procedures conducted in the lab and have supervision at least in the beginning of your lab career.

Biosafety Level 2

BSL-2 labs are used for working with agents that pose moderate hazards to the lab personnel and environment. In these labs you work with pathogenic or infectious agents that can potentially cause human diseases (e.g., Salmonella and Influenza A virus).

BSL-2 labs are separate from other labs and have restricted access. They have self-closing doors with locks as well as a sink for washing near the exit door. The facility should contain the necessary equipment and supplies to decontaminate laboratory wastes (e.g., autoclave). BSL-2 labs must have biosafety cabinets to prevent the spread infectious aerosols or splashes created during normal procedures or by accident.

To work in these labs, follow all the safety rules and regulations for a BSL-1 lab. In addition, make sure you receive specific training in handling pathogenic agents. Always wear protective gear, such as lab coats, eye and face protection, and remember to remove protective clothing before leaving the lab for non BSL-2 areas. If you are working with potential pathogens, you may be required to receive immunizations before you start working. This may not be the lab for you if you are immunocompromised or immunosuppressed.

Biosafety Level 3

BSL-3 labs handle agents that can potentially cause lethal disease through inhalation. In these labs you can work with microorganisms that cause severe human diseases that may be treatable (e.g., Mycobacterium tuberculosis and Yellow fever virus).

These labs must be located separately from unrestricted access areas. They also have special engineering and design features. For example, you enter the BSL-3 laboratory through two self-closing doors and at least the outer door can be locked. The passage between the two doors may contain a clothing change room. Also, at least one hands-free automatically operated sink is required to be located near the exit door. If there are different work zones in the same lab, each zone should have its own sink. The lab must have at least one decontaminating system inside and means to decontaminate all wastes before discarding them. Spaces around the door and ventilation shafts should be sealable for complete decontamination of the area.

Similar to a BSL-2 lab, you need special training on the handling of potentially lethal agents. Your supervisor should have a lot of experience in how to handle infectious agents. Your institute should collect your blood on a regular basis to test for exposure to agents.

Biosafety Level 4

If you are working with any agents that cause life-threatening diseases with no available treatment and have a high risk of aerosol-transmitted infections or you work with agents that have an unknown risk of transmission, then chances are you work in a BSL-4 laboratory. For example, you perform research on Ebola and Lassa viruses in BSL-4 labs. Everybody working in these Level 4 labs should be well trained and your supervisor should be very experienced in that field.

You will find BSL 4 labs in an isolated area away from normal unrestricted access of a building. Sometimes they are located in a completely separate building. The labs are of the highest security: they have non-breakable sealed windows, HEPA filter protected ventilators, self-locking doors, and facilities with a sequential passage containing personal shower and changing rooms. You should use either class III Biosafety cabinets or class I or II BSCs wearing pressure supplied air protective suits. Your institute should provide occupational medical services, offer all possible immunizations, and should collect serum samples from at risk staff regularly.

This was just a brief description of the biosafety levels. You can check out the CDC’s publication on biosafety levels if you want to know more. But just remember: protect yourself properly, take care of your colleagues and the environment and keep up the scientific awesomeness.