These days health and safety measures are more important than ever before. A lot of people work diligently to understand how they can keep their families, clients, business guests, and patrons safe and healthy. This includes familiarizing yourself with a wide range of terms and classifications.

Though did you know that there are different biohazard level classifications? Each of which has its own distinct definitions, and once assigned requires specific remediation, cleaning, disinfecting, or sanitizing measures.

Known as BSL for “Biohazard Safety Levels” they are designed to help protect the environment, as well as laboratory staff members, and the surrounding community.

BSL safeguards are officially categorized by the CDC into four different levels. Each level is meant to differentiate these risks based on the severity of disease, infectivity, transmissibility, and the type of work being carried out at any given time. This also includes additional determining factors such as the exposure method as well as the underlying source of a microbe or some other type of biohazardous agent.

BSLs play an important role in serving to determine the nature of work to be undertaken within a lab setting. In the long run, BSLs dictate how facilities should be designed and which safety equipment to stock.

It’s important to note that these BSL classifications aren’t intended for just laboratory environments. In fact, BSLs are designed to provide structure and guidelines on how biohazard technicians should handle biohazardous situations. They can also play a critical role for first responders and safety personnel in ensuring public safety in the event of an incident.

How Are Biohazard Safety Levels Determined?

Biosafety is a term that is often applied to define the necessary training, safety apparatus, and practices needed to effectively manage biological hazards and infectious microorganisms. This includes specific procedures, and healthcare infrastructure, as well as the development of suitable occupational health plans.

The overarching goal of assigning Biohazard Safety levels is to always safeguard the people working with harmful biological materials. BSLs also ensure that the surrounding environment, the health of the general public, and even native wildlife are all properly protected from dangerous biological agents.

The Four Biohazard Safety Levels

The following Biohazard Safety Level designations are designed to help enhance safety within laboratories as well as in the surrounding community and environment.


BSL One is the lowest parameter of the biosafety pyramid. It contains the different settings that apply in professional laboratories where people work with low-risk microbes. These are considered by the CDC to be the least dangerous to healthy adults. This includes Escherichia coli (E. coli), and similar pathogens.

Lab personnel operating in a BSL One section typically don’t use any special contaminant equipment. Though they do use special protocols and lab equipment to prevent cross-contamination, as well as prevent the potentially dangerous microbes from being released into the surrounding environment.


The BSL Two designation typically applies to professional laboratories that work with human disease-causing agents. These are often infectious or pathogenic organisms that can cause moderate health hazards such as HIV and Staphylococcus aureus.

A BSL two laboratory has stricter rules and increased safety equipment. They also have things like advanced PPEs and follow dangerous procedures within biological safety cabinets. These labs also have an autoclave or other alternative decontamination methods.

BSL Three

A BSL Three environment further enhances the measures contained in the BSL One and BSL Two levels. This includes labs where staff members work on indigenous or exotic microbes. These microbes can cause lethal diseases when inhaled. Some of the common microbes contained in a BSL Three lab include things yellow fever, TB bacteria, and even the West Nile virus.

Technicians in a BSL Three lab wear advanced personal protective equipment, and decontamination procedures when entering and exiting the lab environment. They also use BSCs when working with microbes and air circulation measures where exhaust air does not reenter the lab.

BSL Four

The BSL Four designation typically pertains to labs where employees work with exotic and highly infectious microbes. Many of these pathogens are fatal due to the lack of associated treatment measures or vaccines. This includes things like the Marburg and Ebola viruses.

Technicians working in a BSL Four lab setting must change clothes before entering the facilities. They also need to shower after leaving the facilities and follow strict equipment sanitation rules. This includes wearing full body, air-supplied, positive pressure suits to prevent pathogenic exposure.

Biological Hazard Disposal Protocols

It’s important to note that the CDC and other agencies responsible for maintaining public health view biological hazardous material as any sort of organism or substance that is considered harmful to human health. Many of these organisms are also associated with foodborne disease outbreaks.

Biohazardous materials can include:

  • Viruses
  • Spores
  • Pathogenic microorganisms
  • Io-active substances
  • Toxins
  • Fungi

Materials contaminated by these pathogenic microbes or toxins

Many times, biological hazards can occur in the form of waste products. This includes various types of Infectious waste

  • Pathological waste
  • Animal waste
  • Discarded vaccines
  • Used sharps

Labs that carry a BSL designation must have pre-set managerial functions and procedural standards that focus on confining infectious organisms and poisons to cut the risk of exposure. These processes are meant to protect lab workers from the accidental contraction of the diseases caused by biological hazards.

Of course, Biohazards can mean different things, and there is also a difference between biological hazards and hazardous materials (HAZMAT). The distinction is that biohazardous wastes are organisms or substances that are considered harmful to human health.

Whereas the term “HAZMAT” specifically refers to any materials that can risk the health of people, as well as environmental wellbeing. This can include things like:

  • Residual fuels
  • Toxic chemicals
  • Nuclear wastes
  • Chemical agents
  • Radiological agents

Hazardous material has its own specific disposal protocols that are based directly on the type of waste it is. They are different from Biohazard waste disposal protocols which typically require the pathogenic material to be collected and disposed of following a different protocol. This includes procedures that ensure biohazardous waste is never left in an unsecured public area.