If you’re like nearly every adult in the United States, and elsewhere around the globe, you’ve heard the term “biohazard.” Like most individuals, you likely do not have a truly solid understanding of what constitutes a biohazard. We present you with the essential information you need in order to have a solid understanding of what is meant by a biohazard and the dangers that can exist when contact is made with some sort of biological hazard.

Basic Definition of a Biohazard

A biohazard, also known as a biological hazard, is a biological substance that has the potential for causing illness, injury, or disease to a human being. In layperson’s terms, a biohazard is something that is alive, microscopic, and can make you sick,

Type of Biohazards

The U.S. Centers for Disease Control and Prevention has identified four categories of biohazards or biological hazards. These are:

  • Bacteria
  • Viruses
  • Toxins
  • Other microorganisms

Four Biohazard Levels

The CDC further categorizes biohazards into four levels, based on the degree of risk they present to humans. These levels range from biohazards that present minimal risk to people to those that pose an extreme risk to the lives of humans. The four biohazard levels are discussed in turn.

Level 1

Level 1 biohazards present a minimal risk to humans. The CDC identifies chicken pox as an example of this level of biohazard.

Level 2

Level 2 biohazards do cause diseases in humans; however, the illnesses contracted by these biohazards typically are not fatal and can be treated when promptly diagnosed. The CDC identifies salmonella and some types of influence (flu) in this level of biohazard.

Level 3

Level 3 biohazards are capable of causing severe and even fatal disease. With that said, there are treatments available if a person is exposed to these types of biohazards. The CDC identifies tuberculosis and West Nile virus as examples of this level of biological hazard.

Level 4

Finally, Level 4 biohazards cause severe to fatal illness. There are no treatments for these types of biohazards. An example of biohazards in this category is the Ebola virus.

Primary Considerations Regarding Biohazards

There are four primary considerations that are brought into play when it comes to the dangers of specific biohazards and protecting against the spread of these pathogens. These are:

  • Agent
  • Host
  • Source
  • Transmission


The agent is the type of microorganism that is responsible for causing an infection of a hazardous condition. For example, HIV is an example of such a microorganism.


The host is the living organism that the microorganism infects. By way of example, a human is a host HIV can infect.


The source is a type of host from which the microorganism originates. Using HIV again as an example, the source is a person infected with HIV who passes the virus to another individual


Transmission is the means by which the microorganism goes from the source to another host. When considering HIV, the transmission would include certain types of unprotected contact with blood contaminated with the virus. As an aside, transmission can occur in a number of ways, including:

  • Direct
  • Air
  • Contaminated surfaces
  • Insects

Protection Against Infection

Specific strategies are employed to protect against infection by a biological hazard. At the heart of these protective protocols is the proper use of suitable personal protective equipment. The most essential components of personal protective equipment are:

  • HEPA mask or respirator
  • Protective eyewear
  • Smock, uniform, another type of garment covering
  • Durable gloves

A person should never have contact with a biohazardous substance without first donning appropriate personal protective equipment. Indeed, an individual should not enter into an area in which a biohazard is suspected without first suiting up in appropriate personal protective equipment.

When it comes to personal protective equipment, also known as PPE, the gear must be designed specifically for situations involving exposure to biological hazards. For example, not any old facemask will due. Such a mask must be specifically designed to block penetration by bacteria or viruses (a HEPA mask). Not all masks on the market today have this capability.

Remediation of a Biohazard

The remediation of a biohazard (cleaning up biohazardous situation) is a multifaceted, comprehensive process. Biohazard remediation includes:

  • Removal of biological substances
  • Removal of objects contaminated with biological substances that cannot be cleaned
  • Thorough cleaning of contaminated surfaces and objects
  • Sanitization of the contaminated area

In addition, in some instances, a biohazardous situation results in the presence of a permeating, foul stench or odor. The remediation process will also involve the elimination of that odor. The ultimate objective of biohazard remediation is to restore a home to a completely livable condition or to return another type of premises to a fully usable status.


Emily Kil

Co-Owner of Eco Bear Biohazard Cleaning Company

Together with her husband, Emily Kil is co-owner of Eco Bear, a leading biohazard remediation company in Southern California. An experienced entrepreneur, Emily assisted in founding Eco Bear as a means of combining her business experience with her desire to provide assistance to people facing challenging circumstances. Emily regularly writes about her first-hand experiences providing services like biohazard cleanup, suicide cleanup, crime scene cleanup, unattended death cleanup, and other types of difficult remediations in homes and businesses.