Technicians using the 4 biosafety levels to cleanup a lab.

The 4 Biosafety Levels All Reputable Biohazard Cleanup Companies Should Know and Use

Technicians using the 4 biosafety levels to cleanup a lab.
Technicians with Alabama Bio-Clean, work to clean up a research lab facility.

We talk a lot about biological hazards, and you likely have some knowledge of the more commonly used term “biohazard.” But did you know that there is a system that classifies just how dangerous certain biological hazards are to humans, while setting protocols for how they need to be handled?

What many people fail to realize is that there is a science to the process of biohazard cleanup and remediation, and qualified biohazard cleaning companies such as Alabama Bio-Clean, know and follow these protocols when determining the level of containment needed for a scene. This is one reason why you should always make sure to know the credentials of the technical cleaning company you hire to clean up biological hazards and waste.

Biosafety Levels (BSL), or pathogen/protection levels, are a set of biocontainment precautions required to isolate dangerous biological agents in an enclosed laboratory facility to ensure the safety of laboratory staff, the environment and the surrounding community. In the U.S., the Centers for Disease Control and Prevention (CDC) sets the biosafety levels, ranked one through four, and corresponding safety protocols based on the primary risks that determine levels of containment including, infectivity, severity of disease, transmissibility and the nature of the work conducted, among others.

Alabama Bio-Clean, trained and certified technicians use these levels as a guide for how to handle certain cleanup situations, especially during lab cleanings, which ensures not only the safety of our own staff but also of anyone else present at the scene.

The 4 Biosafety Levels

The four biosafety levels are set by the CDC based on the agents or organisms that laboratory personnel are researching or working on. Levels range in order from the lowest biosafety level 1 (BSL-1) to the highest at level 4 (BSL-4). For example, the lowest level of biosafety precautions may consist of regular hand-washing and minimal protective equipment, while the highest level of biosafety precautions may consist of multiple containment rooms, sealed containers, heavier PPE, extensive personnel training and a high level of security access to the facility.

Biohazard safety levels are important because they help define the type of work practices allowed to take place in a lab setting and the type of safety equipment needed. Learn more about the 4 biosafety Levels below!

Biosafety Level 1 (BSL-1)

BSL-1 is the lowest of the four biosafety levels and applies to laboratories in which personnel work with low-risk microbes* that pose little to no threat of infection to healthy adults. An example of a microbe that is typically worked with at a BSL-1 is a nonpathogenic strain of E. coli.

According to the CDC, safety protocols for Biosafety Level 1 labs include:

  • Safe sharps handling
  • Avoidance of splashes or aerosols
  • Daily decontamination of all work surfaces
  • Regular handwashing
  • PPE to include lab coats, gloves and eye protection worn as needed
  • Biohazard signs
  • Prohibition of food and drinks

BSL-1 labs also require immediate decontamination following spills. BSL-1 laboratories are often used as teaching spaces for high schools and colleges.

Biosafety Level 2 (BSL-2)

BSL-2 labs build upon BSL-1 but also work with agents associated with human diseases (pathogenic or infectious organisms) that pose a moderate health hazard. Examples of BSL-2 agents could include HIV, hepatitis A, B and C, or Staphylococcus aureus (staph infections), among others.

At this level, all precautions used at BSL-1 are followed as well as some additional precautions, including:

  • Lab personnel have specific training and are directed by scientists with advanced training
  • Access to the lab is limited when work is being conducted
  • Extreme precautions taken with contaminated sharps
  • Certain procedures that could cause infection from aerosols or splashes are performed within a biological safety cabinet
  • PPE worn includes lab coats and gloves, with eye protection and face shields worn as needed
  • Decontamination of infectious materials prior to disposal, generally through the use of an autoclave*
  • Lab has self-closing, locking doors

Biosafety Level 3 (BSL-3)

Biohazard safety level 3 builds on the prior two biosafety levels as well and includes research into or work on microbes that are either indigenous or exotic which can cause serious to potentially lethal diseases through inhalation. This type of research is typically conducted in clinical, diagnostic, teaching, research or production facilities. Example of BSL-3 agents includes West Nile virus, yellow fever virus, SARS-CoV-1 and SARS-CoV-2 and the bacteria that causes tuberculosis, among others.

BSL-3 lab settings often have the potential to be so hazardous that labs are registered through appropriate government agencies and personnel are under medical surveillance or may require immunizations for the microbes they work with.

Additional safety precautions in BSL-3 labs include:

  • Restricted and controlled access to the lab always
  • PPE must be worn, and respirators might be required
  • Solid-front wraparound gowns, scrub suits or coveralls are often required
  • Access to hands-free sink and eyewash station available near the exit
  • Sustained, directional airflow only is required by drawing air into the laboratory from clean areas towards potentially contaminated areas

Biosafety Level 4 (BSL-4)

BSL-4 labs are used for diagnostic work and research on easily transmitted pathogens that can cause fatal diseases. According to the CDC, microbes in a BSL-4 lab are dangerous and exotic, posing a high risk of aerosol-transmitted infections. Infections caused by these microbes are frequently fatal and without treatment or vaccines and include such microbes as Ebola and Marburg viruses. There are only a small number of Biosafety Level 4 labs in the U.S. and around the world.

In addition to all safety considerations of BSL-3, BSL-4 labs have the following containment requirements:

  • Personnel much change clothing before entering, shower upon exiting and decontaminate all materials
  • Work is performed in full body, air-supplied, positive pressure suits*
  • The lab is in an isolated building, in a restricted zone
  • All work is performed within a Class III BSC, or biological safety cabinet*
  • The lab has a dedicated supply and exhaust air, as well as decontamination systems

According to a 2015 study by USA Today, there are no more than 200 lab sites in the U.S. that are accredited biosafety levels 3 or 4.

Take this quick CDC quiz on recognizing biosafety levels to learn more about this topic.

A simple visualization for biosafety levels courtesy of UC Riverside Environmental Health and Safety.

Alabama Bio-Clean Process for Ensuring Safe and Clean Laboratories

The CDC recognizes that each lab setting is different. However, they each have a common need — protection from contamination.

Alabama Bio-Clean, works with lab staff all throughout the state to ensure that their daily goals for cleanliness and sanitization are met and that protocols based on industry-standard practices are in place for emergency situations.

Our highly trained technicians use the Spaulding Classification to determine the best method for cleaning medical devices and their necessary levels of disinfection. The Spaulding Classification is defined by the CDC as a “strategy for sterilization or disinfection of inanimate objects and surfaces based on the degree of risk involved in their use.”

We determine what chemical disinfection strategy to use by classifying devices and situations in such a way:

  • Disinfection Level: Non-critical. This level is for devices that come into contact with intact skin. They require a low-level disinfectant (also known as “hospital disinfectants”), which kills most vegetative microorganisms*, and some fungi, and inactivates some viruses.
  • Disinfection Level: Semi-critical. This level is for items that have come into contact with mucous membranes or non-intact skin. It requires an intermediate level of disinfection (which may be used for housekeeping and disinfection of lab benches), which kills vegetative microorganisms, all fungi and inactivates most viruses.
  • Disinfection Level: Critical. Critical devices have come into contact with the bloodstream or other sterile areas of the body. This requires a high level of disinfection and comprises a high concentration of chemical germicides, which kills vegetative microorganisms and inactivates viruses.

In addition to this process, our team cleans and disinfects surfaces such as floors and walls that do not usually come into direct contact with lab workers or equipment, and we’ll do this using state-of-the-art equipment and the best chemicals on the market.

Our cleaning, disinfection and sterilization services are frequently hailed by clients we work with at tissue banks, pharmaceutical research labs, pathology labs and cleanrooms for medical or electronics research and manufacturing all throughout the state of Alabama.

The integrity of your lab and the safety of your workers is your top priority — and it’s also ours. Contact Alabama Bio-Clean, today for lab cleaning services at 866-513-0450.


AUTOCLAVE. An autoclave is a type of equipment used to decontaminate biological hazardous waste or to sterilize equipment and supplies by subjecting them to high-pressure and saturated steam.

BIOLOGICAL SAFETY CABINETS. Biological safety cabinets are gas-tight sealed containers that are designed to allow for the manipulation of objects, hazardous substances, or infectious disease agents. Class III BSCs have a HEPA-filtered air supply and double HEPA-filtered exhaust. They provide the ultimate protection for personnel, product, and the environment.

MICROBES. Microbes are microorganisms that are naked to the eye; while some are important to our health, others can make humans sick.

POSITIVE PRESSURE SUITS. Positive pressure suits are highly specialized, totally encapsulating industrial protection garments worn only within special biocontainment or maximum containment laboratory facilities. The positive pressure in the suit will force air to flow out if the suit is damaged.

VEGETATIVE MICROORGANISMS. Vegetative microorganisms are bacterial cells that are actively growing such as what you might find in Staph infections and Salmonella.